Summarize the common problems and answers in sewage treatment practice:

Question 1:

Process: hydrolysis + contact oxidation method. The COD of effluent is 70mg / L, but it looks very turbid. I don't know why? Is the method of measuring MLSS the same as that of Measuring SS?

answer:

(1) If too many suspended particles enter the contact oxidation tank, it will passively lead to the increase of SS in the effluent of the contact oxidation tank. In this way, the effluent will be turbid. If inorganic particles are dominant, SS is high, while effluent COD is not high.

(2) The detection methods of MLSS and SS are the same, but the filter paper is easy to be blocked by activated sludge during MLSS filtration. It is best to use suction bottle for suction filtration. ‍

Question 2

The water quality of our company's sewage in some sedimentation tanks and biochemical tanks in phase III and some sedimentation tanks and biochemical tanks in phase II deteriorates and turns black, but the pH value is about 7.3 and the aeration gas is normal. What is the reason for the above situation?

answer:

(1) Normal aeration can only ensure the normal operation of the aeration tank. If the residence time of the sedimentation tank is too long and the COD treatment effect of the water quality is poor, the water quality can be blackened

(2) If the municipal sewage has a long inlet pipeline, the water quality will turn black due to lack of oxygen before entering the sewage treatment system. In this way, the outlet treated water will also turn black. ‍

Question 3

How is the yellow green effluent of the final sedimentation tank caused?

answer:

(1) In the treatment of urban domestic sewage, the incoming water color is black due to anoxia in the sewage pipe on the way, and the treated effluent is yellow and green.

(2) The same is true for some industrial wastewater. The effluent color is abnormal, which is mostly caused by water inflow. ‍

Question 4

There are many small pieces of sludge floating out of the effluent. The process is Carrousel oxidation ditch. The influent cod is 450mg / L, the water temperature is 14 ℃, the effluent COD is 200mg / L, SV30 = 50mg / L, there are many clock insects, the dissolved oxygen in the effluent is 2.50mg/l, and there is always debris for 10d. What is the reason?

answer:

(1) The first consideration is sludge disintegration. The common is aging disintegration. Check whether the F / m value is too low, that is, whether the MLSS is too high. If so, appropriate sludge discharge shall be carried out (generally, the MLSS control in winter is 10% - 15% higher than that in summer).

(2) If the number of bell worms is guaranteed, the inflow is relatively stable, but it is necessary to see whether there are filamentous bacteria under the microscope. If filamentous bacteria exist, fine particles will flow out of the discharged water when the inflow fluctuates too much. ‍

Question 5

The CASS process is used in our factory. When we aerated a few days ago, the dead mud was black on the foam. The dissolved oxygen increased rapidly and the water was muddy. What is the reason?

answer:

(1) do not know the removal rate of organic matter. If there is little effect, it may be that the water contains non degradable material and adhered to the foam through aeration. So, let's see if there is an abnormal SS in the water, including whether the color of suspended solids is consistent with the color of the foam.

(2) If the organic matter removal rate decreases, consider whether the influent has ingredients that inhibit microorganisms. If possible, see if the wastewater discharged from the source has changed.

(3) Will any chemicals be added to the sewage treatment plant? There is also a situation where the aeration equipment and mixing equipment in some places have failed, and they are suddenly repaired or opened to stir the sediment at the bottom of the tank. The same phenomenon will occur. ‍

Question 6

80% of the factory is industrial sewage, most of which is papermaking water. There are filamentous bacteria in the mud, but the quantity is not large. The factory is in Shandong. The water temperature is 14 degrees Celsius, a little floating mud, which is very serious. Is the sewage treatment plant in North China like this in winter?

answer:

(1) If there is bleaching sludge in papermaking wastewater, check whether it is sludge aging (according to f / m value)

(2) Analyze the influent composition to see whether the fine calcium carbonate has been settled and whether there are difficult to settle mineral particles of coating wastewater. If there is such a situation, the materialization stage should be strengthened. ‍

Question 7

70% of our products use reactive dyes. The process is hydrolysis (hrt12h) - contact oxidation (hrt10h) - coagulation sedimentation (hrt4h) - effluent. The COD of the effluent from the oxidation tank (after static sedimentation) is 150mg / L and the chromaticity is about 200. A variety of drugs (aluminum sulfate and decolorizer, lime and ferrous sulfate) have been used. Due to the transformation project, the effluent after coagulation dosing for 4H is very easy to turn color, but the cost is too high or the COD chroma can not meet the standard at the same time. I wonder if there is a better medicine?

answer:

(1) Dye wastewater is a kind of industrial wastewater which is difficult to treat.

(2) Whether there are color control requirements for the discharged wastewater. In addition to the biochemical section and decolorizer, the physicochemical section is also important for the reduction of COD and color. If the chroma can be effectively removed through the physicochemical section, the pressure in the rear section will be greatly reduced.

(3) The choice of decolorizing agent is to treat the wastewater appropriately, and the appropriate type of agent can be determined through experiments. ‍

Question 8

The treatment station operates normally. At the beginning, the effluent is not good, brown yellow, but the anaerobic effluent is very clear, and the effluent is not good after passing through the oxidation ditch. At present, the effluent from the oxidation ditch is still muddy, and the water is still brown. I don't know how to do it. When aeration, the liquid foam has a little green, and now it wants to remove the chroma of the effluent.

answer:

(1) the liquid foam is green, usually with anaerobic parts and municipal sewage.

(2) If the activated sludge does not reach the appropriate concentration, the problem of yellowish brown effluent can occur in the bacteria culture stage, because the bacteria culture of activated sludge is not mature, the sludge activity is high, and the agglomeration flocculation is insufficient. ‍

Question 9

What I'm debugging now is the wastewater from mechanical industry. First physicochemically add lime and ferrous sulfate, then enter the primary sedimentation, and then go to the contact oxidation tank. The total residence time is 30 hours. The secondary sedimentation effluent, COD inflow 2000mg / L and effluent 20mg / L. The total P influent is 60mg / L and the effluent is 0.9mg/l. The problem now is that I have been debugging for about a month, and the ammonia nitrogen and COD meet the standard, that is, the total P is high. After dosing, the total P content in primary sedimentation is only 0.05, but in secondary sedimentation, the total P content increases to 0.9mg/l. The experimental results are absolutely no problem. I wonder if anaerobic P release occurred in my biochemical tank or secondary sedimentation, but after I discharged the sludge from secondary sedimentation and biochemical tank, I found that there was not much sludge. What is the reason for this phenomenon?

answer:

(1) Generally, the effluent P will be less than the influent P concentration. If it is reversed, it is only temporary and phased (considering that microorganisms can enrich P)

(2) In terms of energy conservation, the problems mentioned above will not occur. As the total phosphorus in the influent is too high, as long as there is leakage in the physicochemical section, a large amount of phosphorus will enter the contact oxidation tank, resulting in the rise of total phosphorus in the effluent.

(3) The process does not have effective phosphorus removal capacity, which is also the key to this problem. ‍

Question 10

Before the biological contact oxidation tank was in the commissioning stage, it was always in good condition, with water inflow of about 200mg / L and water outflow of about 30mg / L. however, after a period of time, after full load operation, the filler of the last two of the three tanks appeared brownish red. Now there are fewer and fewer membranes, and there are many red insects, which can be seen by the naked eye. There are a lot of suspended solids in the effluent, and the water quality has become worse. It has been very clear before. Dissolved oxygen was always controlled at about 3mg / L before, but now it is 2 ~ 3mg / L. What the hell is going on?

answer:

It should be said that the alternating renewal of biofilm needs the of these protozoa. Excessive load may be related to low load. The aeration rate can be reduced appropriately. ‍

Question 11

The wastewater mainly contains resin, 5 ~ 6% isopropanol, 300 cubic meters of water a day, mixed with 50% domestic wastewater, mainly canteen wastewater. The influent cod is very unstable, with an average of about 1200, but the maximum cod can reach 15000. The original process flow is: regulation - Chemical Flocculation - sedimentation - facultative oxygen - aerobic - inclined plate sedimentation - adsorption - effluent. The effluent condition: it fails to meet the standard for 15 days a month (200 ~ 400 on average), Average cod1300, when cod reaches 10000 or more, the biological part of effluent (400 ~ 600): anaerobic influent is from top to bottom. There are few organisms on the filler, almost no biological thickness, the sludge on the aerobic membrane is yellow, the inside is black, and the water is clear. The biological thickness on the filler is about 5cm. Pinch open the biological particles like jelly. I don't know what it is. What is the problem with the original process organisms? The COD entering the reaction tank is lower than that of the biological effluent. The effluent sometimes meets the standard and sometimes does not meet the standard. The failure to meet the standard in 15 days is only average. Sometimes it meets the standard in one month and then it does not meet the standard in two months. The residence time of the regulating tank is 10 hours, the reaction time is 1 hour, facultative oxygen is 4 hours, aerobic oxygen is 6 hours and the sedimentation time is 2 hours. What is the reason?

answer:

It's still a water problem.

1. The concentration changes greatly, and the microorganism can't keep up with the change

2. The organic matter contained in water is not easy to degrade. Especially isopropanol (organic solvent), like gasoline, is not easy to degrade. It is necessary to increase the residence time to improve the degradation rate. ‍

Question 12

CASS process, the previous days, when aerated, the foam adhered to dead mud and was black. The solution was raised rapidly and the effluent was cloudy. What is the reason?

answer:

(1) do not know the removal rate of organic matter. If there is little effect, it may be that the water contains non degradable material and adhered to the foam through aeration. So, let's see if there is an abnormal SS in the water, including whether the color of suspended solids is consistent with the color of the foam.

(2) If the organic matter removal rate decreases, consider whether the influent has components that inhibit microorganisms. If possible, see whether the wastewater discharged from the source has changed.

(3) Is there any medicine added in your sewage plant? There is also a situation where the aeration equipment and mixing cup in some places fail, and they are suddenly repaired or opened to stir the sediment at the bottom of the tank, which will also lead to the phenomenon you said. ‍

Question 13

The daily average water inflow of the sewage unit of the chemical plant is 500-600, the influent cod10000 is about, and the effluent cod200 is about. The process is pretreatment + anaerobic biochemistry + aerobic Biochemistry (complete mixing method), mlss7.9g; The abnormal condition of sv3085% is that some time ago, due to the high ammonia nitrogen containing wastewater (about 700) from the company's coal to gas unit entering aerobic biochemistry, the effluent ammonia nitrogen has been high, the effluent ammonia nitrogen is about 200, and the effluent cod200. Due to the strict environmental protection indicators, the coal to gas wastewater was stopped receiving half a month ago. Now the problem is, Half a month ago, we stopped receiving high ammonia nitrogen wastewater. Now the influent ammonia nitrogen is about 20 and the effluent ammonia nitrogen is about 200. What is the reason and how to deal with it?

answer:

(1) The operation of the system is quite good. From the data, the COD removal rate has reached 98%. After being impacted by high ammonia nitrogen, the COD removal rate has not been reduced.

(2) Stopping the acceptance of high ammonia nitrogen now should slowly reduce the ammonia nitrogen in the effluent. At present, it is still relatively high. It should be the ammonia nitrogen retained in the system. After all, the ammonia nitrogen in the influent is only 20. ‍

Question 14

Our plant is an AAO Process, with a design capacity of 25000, the actual influent is about 20000, the influent cod is 300-500, and occasionally more than 600, but very few. The influent ammonia nitrogen is about 35-40, MLSS is now 8000, SV30 is 50 and do is about 3. Now the effluent COD is between 50-60, ammonia nitrogen is stable at 1 and SS is 8-10. In the past, our effluent COD has been relatively stable and up to standard, and now it rises suddenly. I don't know why?

answer:

Judging from SV30:

(1) The turbidity of supernatant, especially the turbidity of interstitial water, needs to be considered due to the sudden increase of load (judged by whether the COD of influent water also increases). It may also be the inflow of refractory components. It can be judged by cooperating with the microscope to see whether protozoa have a decreasing trend.

(2) There are many particles in the supernatant, but the water between the particles is relatively clear, which may be due to the aging of sludge and more effluent particles. The COD released by the particles can be measured after filtration with effluent filter paper to determine whether the COD is lower than that without filtration. According to the above investigation, the countermeasures will be discussed after the causes are determined. ‍

Question 15

The influent cod60-150mg / L is domestic sewage, circulating water and sewage. The effective volume of the aeration tank is 10000 m3 (a series of 5000 m3 is currently out of service), with four sections of surface aeration and a secondary sedimentation tank behind it. The influent is low in ammonia nitrogen and the influent pH is 6-8. The water volume is 500-600 tons per hour. The sludge concentration is 5g / L, which is planned to be controlled to 3G / L. at present, the main problem is that the effluent SS is high. For our convenience, we measure turbidity. If the turbidity is below 20ntu, the rear depth device operates stably, but now it is usually at 30ntu. The sludge concentration must be high, but it has also decreased by 3, but the effluent is still unstable. Is there any good process improvement method to reduce effluent turbidity?

answer:

If the sludge concentration is 5000, the effluent SS is really easy to be high. Therefore, as you proposed, it should be slowly reduced to 3000 to see the effect. ‍

Question 16

The Baijiu wastewater was specially disposed in the oxidation ditch two sedimentation tank. The phosphorus removal tank was removed by PAC. The ammonia nitrogen in the effluent was about 0.5. Total phosphorus was 1mg/L. In summer, when the sun was bigger, the pond surface was covered with moss and duckweed. What are the reasons and how to control it?

answer:

(1) The reason for a large number of problems is that the nitrogen and phosphorus content of your effluent is high (but also up to the standard). Because your effluent is flowing, the nitrogen and phosphorus concentration provided is not limited for these algae.

(2) In case of countermeasures, reduce the nitrogen and phosphorus concentration of effluent from the source and salvage regularly.

(3) In addition, if the effluent deteriorates (such as cod and SS), these algae and plants will decrease. Therefore, the presence of these algae and plants can actually help judge that the effluent quality is good (COD and SS)

Question 17

The effluent COD of one of our plants suddenly reaches about 100, the suspended solids are slightly higher, and the water is still relatively clear; It has been around 30 before, and the inlet water quality has not changed much. It is basically all domestic sewage! Do is basically about 2 ~! What's wrong with operation control?

answer:

1) After filtering these suspended solids, see how much cod is. If the COD is greatly reduced after filtering, it indicates that the COD of effluent is increased due to the floating of activated sludge. If the change of COD after filtration is not obvious, the increase of COD in effluent is caused by dissolved organic matter.

2) In view of the above, the countermeasures are as follows: (1) the COD measured after filtration is significantly reduced, and the effluent is still clear. Pay attention to whether it is caused by sludge aging, which can be alleviated by gradually discharging sludge. (2) If there is no change in COD measured after filtration, it is mostly caused by the increase of influent organic matter or the increase of F / M caused by too much sludge discharge. Overall, the first possibility is high. ‍

Question 18

Now do debugging a pharmaceutical wastewater, COD 20000, poor biodegradability. Anaerobic effluent 3000-5000 into facultative oxygen, more than 1000 into biological contact oxidation tank, but there are more than 700 effluent recently. During this time, there is always floating mud on the aerobic tank, sometimes yellow and sometimes grayish black. I suspect that the sludge is aging and the effluent is very turbid, SV only 5. Some time ago, due to the pressure of the manufacturer, the load was raised a little quickly, but later it slowed down, but the effect has been very poor. Is there any remedy for this aerobic?

answer:

Biological contact oxidation process is a symbiotic state of membrane sludge. For refractory organics, if the biochemical property is poor, it is better to mainly rely on membrane for treatment. Therefore, the sludge discharge can be increased and the residence time of wastewater in the contact oxidation tank can be prolonged. It is not easy to reduce 20000 cod to more than 1000 through anaerobic and facultative oxygen. ‍

Question 19

The Carrousel oxidation ditch for municipal wastewater has no primary sedimentation tank, the water volume is 60000 tons / day, the influent cod120 mg / L, the sludge load is 0.04 kgbod / kgmlss. D, the sludge age is controlled at 20 days, the sludge concentration is 2500, sv30:20%, the effluent COD is 20 mg / L, and the original sludge concentration has been controlled at 3000 mg / L. after the festival, it is found that the effluent is turbid, the sludge concentration decreases, the sludge aging is analyzed, and the influent load is low, Reduce the sludge concentration and control it at about 2500mg / L. however, in the process of reduction, SV also decreases rapidly, from 40% to 20%. It is turbid. There is no big fluctuation in effluent COD, and the effluent SS is up to 20mg / L. however, from the perspective of SV30, the supernatant is turbid and the effluent is hazy. SV has been decreasing, and the effluent is not as good as before the festival. What is the reason?

answer:

The main thing is to pay attention not to reduce the sludge concentration too quickly, that is, not to reduce too much at once. At present, it is really the aging of sludge and the turbidity of effluent, or to see for a period of time after the sludge discharge is increased. After it is stable, determine whether to continue to increase the sludge discharge, otherwise it is easy to reduce too much at once, which will affect the effluent stability. ‍

Question 20

Our plant is a landfill leachate treatment project of garbage power plant, which adopts UBF + Dual A / O system for treatment. The effluent was OK before the year, but after the year, the effluent COD: 456, ammonia nitrogen: 80, a little exceeding the standard, sludge concentration: 15g / L, sv: 75%, (o tank) do: the probe shows 0.5, (there is a problem in the estimation of the probe), and the effluent is a little red. What conditions should be changed to make the effluent meet the standard (up to standard cod500, ammonia nitrogen 35)?

answer:

The low dissolved oxygen may be related to the high sludge concentration. You also said that the dissolved oxygen may be inaccurate, so please confirm whether the dissolved oxygen is accurate. Now look at the data, there is a correlation between the high ammonia nitrogen and the low dissolved oxygen. If the dissolved oxygen is submitted, the ammonia nitrogen should be reduced. In addition, please inform us of the pH value

Question 21

The effluent COD is continuously higher than the influent cod. How to solve this situation?

answer:

(1) If the MLSS is not greatly reduced, it is necessary to consider whether there are inhibitory substances in the influent, resulting in no removal rate even if there are MLSS. If there are inhibitory substances, in addition to contacting the inflow of inhibitory substances, it is necessary to increase the sludge discharge and discharge the inhibitory substances, so as to restore the system through the formation of new sludge.

(2) If there is still a large amount of activated sludge flowing out, resulting in high laboratory data, you can monitor cod after filtering impurities to see if there are different data. If the COD data after filtering is reduced, ensuring the sedimentation of activated sludge is the first thing

Question 22

Our sewage treatment plant is an inverted A / A / O process. The effluent is of class a standard. The influent cod is about 400mg / L, BOD is about 300mg / L, and the influent volume is 10000 m3 / day. In the early stage, the sludge has not been discharged for about a year. Last month, the effluent began to turn yellow, and COD, SS and chromaticity did not meet the standard. Now the sludge has been discharged continuously for one and a half months, and the sludge concentration has dropped to 6000mg / L, SV is 40. Now, there are still the following problems There are a lot of floating black mud mud on the surface of the aerobic pond; dissolved oxygen has not been able to rise at about 1; two, the effluent from the sedimentation tank is cloudy, and the total effluent has foam; what should we do to the follow-up COD100mg/l of the effluent?

answer:

(1) Don't discharge sludge too quickly at once. Otherwise, the balance between organisms will be suddenly destroyed and the effluent will deteriorate.

(2) The sludge concentration of 6000 is still too high. After all, the influent organic matter concentration is not high, and 3500-4000 is more appropriate

(3) The effluent is yellow, turbid and scum, which can be understood as sludge aging. Therefore, you are right to discharge sludge

Question 23

Our plant is an urban domestic sewage and a public art of BlackRock. It has a design treatment capacity of 30000 tons, and now the influent is 18000 tons. The average influent cod is about 180mg / L, the sludge concentration is 3600mg / L, the sedimentation ratio is 14, and the dissolved oxygen is about 2mg / L. what I face now is:

1. When two fans are turned on, the sludge concentration is 3600mg / L. when one fan is turned on, the sludge concentration is only about 2400mg / L. if the second fan is not turned on for two days, the sludge concentration is 1800.mg/l. Will sludge corruption occur if only one fan aeration tank is turned on for a long time.

2. A small amount of sludge floats up in the secondary sedimentation tank. The suspended solids in the effluent are high, about 120mg / L. with the high phosphorus, the effluent COD online monitoring is only about 15mg / L, and the ammonia nitrogen is 0.1mg/l. The water surface on the side connecting the secondary sedimentation tank and the aeration tank is very clear, but the side of the effluent weir is very turbid. What's the matter?

answer:

(1) When the aerator is turned on more, the stirring and driving force will increase, so the measured sludge concentration will be high. Conversely, the sludge will settle in the biochemical tank, and the detected sludge concentration will be low.

(2) As for the turbidity of the effluent, it is mainly caused by the aging of the sludge caused by the low concentration of organic matter in the influent and the relatively high sludge concentration control. Therefore, it is necessary to discharge the sludge to reduce the sludge concentration

Question 24

My intermediate sedimentation tank is suspended with suspended solids, white and light. The aeration tank has white and easy to accumulate foam. Biological contact oxidation is used in aerobic biochemistry. What is the reason for the suspended solids?

answer:

(1) Due to the biological contact oxidation method, the biofilm may peel off after aeration, and the peeling material is not easy to settle after being broken by aeration, resulting in the phenomenon you said.

(2) Please compare suspended solids and biofilms to see if they are similar substances.

(3) If you are running intermittently, you'd better stop aeration when stopping water inflow to reduce the peeling phenomenon caused by scouring biofilm

Question 25

In Ao process, the water sample on pool o will float up after being put in the afternoon. If it is gently shaken, it will sink immediately. Is this due to insufficient aeration? More than 400 cod influent, and the effluent can only be more than 200. The NH3-N removal rate will be very high at that time. 300 can be reduced to about 5. Sv517% sv3011%, and the influent is about 60 tons per day. There are often scum on pool a, which looks like rotten mud. What should I do The operation is better? We require the effluent to meet the first-class standard. In the later stage, we also added PAC and PAM coagulation sedimentation, and the COD is still about 120mg / L.

answer:

(1) It should be caused by insufficient aeration. I'm afraid the high COD in the effluent is also caused by some sludge floating up into the water after breaking up.

(2) With such a high ammonia nitrogen removal effect and insufficient dissolved oxygen, it is easy to cause the sludge to float up after denitrification

Question 26

For the sewage treatment project in the service area, the design inflow is 180 tons. The process is Ao process. Now the inflow is about 80 tons per day. It operates for 10 hours during the day and does not operate at night. The influent cod is about 160 mg / L, ammonia nitrogen is 120 mg / l to 180 mg / L, the influent pH is about 8.4, the anaerobic tank pH is 7.6, and the aerobic tank is about 7.5. Add 25 kg of glucose every day, the dissolved oxygen is about 5, and turn off the fan at night without aeration. Sludge The sedimentation ratio was about 30%. The bacteria were re cultured two months ago. The biofacies were good when the microscopic examination was done 20 days ago. All the indicators of effluent were good. Now the ammonia nitrogen had no removal effect, and the removal rate was 20%. There was no sludge discharge from 20 to 10 days ago, and the sedimentation ratio increased from 25 to 35. The sludge discharge began in 10 days. Now the sludge sedimentation ratio is about 30, and the effluent is turbid. How should I adjust the operation?

answer:

There may be too much glucose added. Please try to reduce it gradually (about 1 week) to see if the ammonia nitrogen removal rate is improved. Also see the ammonia nitrogen in the effluent. The treatment effect is 1 hour, 5 hours and 10 hours after the start of operation. This can be used to judge whether the treatment effect is good at that time

Question 27

CASS process is adopted in our plant, with a design capacity of 30000 tons / day and a current capacity of 20000 tons / day. The influent cod250mg / L, ammonia nitrogen 45mg / L and tp4.2mg/l, the effluent cod45mg / L, ammonia nitrogen 12-20mg / L and TP less than 1mg / L. the operation cycle is 4H, influent 2h, sedimentation 1H and drainage 1H, in which the aeration is 1-1.5H according to the conditions of each tank. In order to reduce ammonia nitrogen, the aeration is increased in the middle of March After 5-4h, the sludge concentration is 5000-7000mg / L, MLVSS is more than 1000 points, and do is between 1.5-4mg / L. after adjusting the process, the effluent turns earthy yellow, and a large amount of dead sludge floats during sedimentation. In order to discharge the floating sludge, increase the sludge discharge at 15 tons / day. Now, the effluent sense of some tanks has improved, but the ammonia nitrogen is very high, about 20mg / L, while some tanks appear earthy yellow again, and the ammonia nitrogen is better, at 1 2mg / L or so. Let's see if you have any suggestions. How to form and control this earthy yellow? 2. Is the ammonia nitrogen in our plant due to the death of nitrifying bacteria and how to reduce the ammonia nitrogen now. From the middle of March to now, the ammonia nitrogen reduction effect is not obvious. This week, I reduced the sludge discharge by 8 tons / day, but some ponds will have sludge in the effluent. The effluent from our plant will be discharged Since last October, there have been lots of white bubbles at the outlet. What are the reasons? What is the reason? If TP influence, but when we have good total phosphorus, there are still bubbles. If it is a surfactant, there is no bubble when the biochemical tank is aerated. What's more, the Environmental Protection Bureau is not high when measuring, and the water is only about 0.01mg/l.

answer:

(1) First, look at the removal rate according to your process. The removal rate of ammonia nitrogen is about 50%, which is really not high. Generally, it can be achieved above 80%.

（2） The removal of total phosphorus is more than 75%. According to the principle of nitrogen and phosphorus removal process, it can be guided that long sludge age is required to ensure the nitrification effect, and timely sludge discharge is required to improve the phosphorus removal. Therefore, these two are actually a contradiction. At the extreme, the effect of the other side will become worse. Therefore, if the balance is reached, the respective removal rates of nitrogen and phosphorus removal will be about 80%.

(3) From your data, we can see that nitrogen removal is poor and phosphorus removal is good. Therefore, we can know that you have kept up with the sludge discharge.

(4) Because your sludge concentration is too high corresponding to your influent concentration and the active ingredient is low, you should increase the sludge discharge to improve MLVSS. In this way, the ammonia nitrogen removal rate will deteriorate, but when you improve MLVSS, the ammonia nitrogen removal rate will be further improved.

(5) Therefore, if the balance is finally reached, that is, the removal rates of ammonia nitrogen and total phosphorus are about 80%, the system is in a better state

Question 28

Under normal operation, what is the reason why the effluent color has been yellow?

answer:

The following are possible:

(1) The water is inherently colored

(2) Sludge disintegration causes the effluent to have the color of sludge (sludge aging, sludge poisoning, etc.)

Question 29

At present, I am in charge of a printing and dyeing wastewater plant. The process adopted is activated sludge + air floatation. When the temperature changes suddenly every spring, autumn and winter, the water plant has problems, and the effluent COD and ammonia nitrogen exceed the standard. Air floatation has been well controlled. It should be the problem in the activated sludge tank. Microscopic examination found that the biological phase is bad at this time, and there are few microorganisms. What is this What are the causes? What preventive measures should be taken at this time in the future?

answer:

(1) If the water temperature is low, it will naturally affect the treatment effect of the system. At this time, it is necessary to increase the activated sludge concentration.

(2) As it also has the requirements for the treatment of ammonia nitrogen, attention should also be paid to the control of pH value and sludge age

Question 30

Now there are some emergencies in our plant. Ammonia nitrogen and total nitrogen have exceeded the standard since the winter of 2011. Occasionally, they can reach the standard in a few days, and the floating mud is particularly serious. A large amount of floating mud will be produced every day (the water temperature in winter is greater than 12 ℃) The details are as follows: the improved oxidation ditch process used in the plant adopts two groups of surface aeration. The design water volume is 40000 tons, and the actual control water volume is about 3 tons per day. The influent is mainly domestic sewage. There are several large chemical parks around the plant. The chemical park has its own sewage plant, and the inspection is strict, because the pipe network is also managed by ourselves. The influent water quality cod = 350mg / L, Ammonia nitrogen = 50mg / L, TN = 60mg / L, TP = 4 ~ 7Mg / L, BOD = 120mg / L, pH = 7.8 ~ 8.1, ORP = - 100mV or so. Effluent COD = 50mg / L, ammonia nitrogen = 25mg / L, TN = 29mg / L, TP = 1mg / L, BOD = 10mg / L, pH = 7.5 ~ 7.6, process parameters: oxidation ditch outlet do = 1.5 ~ 2.6mg/l, MLSS = 2000 ~ 2500mg / L, reflux ratio r = 100 ~ 120%, food micro biomass ratio 0.1 ~ 0.12kgbod / kgmlss * D, SRT is 7 days. Now, the small-scale and pilot scale systems are running synchronously It has collapsed, and the sludge is not long, but plummets. Now it is worried that the same situation will happen in the productive oxidation ditch. Now the floating sludge in the oxidation ditch is particularly serious, and MLSS is also declining. What are the reasons and aspects to consider?

answer:

(1) Overall, the ratio of influent organic matter to total nitrogen is unbalanced, that is, influent organic matter is low and total nitrogen is high.

(2) As the temperature is not high and the dissolved oxygen in the oxidation ditch process cannot be fully guaranteed, the removal of ammonia nitrogen will be affected.

(3) It is suggested to relax the COD value under source control to correct the ratio of organic matter to total nitrogen, which is conducive to your ammonia nitrogen and total nitrogen removal

Question 31

The process of the small sewage treatment plant we do is lift well - grid well - regulating tank - reaction tank - inclined plate sedimentation tank - hydrolytic acidification tank - MBR tank - sludge tank. There are lift pumps in the lift well, blowers and submersible sewage pumps in the regulating tank, submersible agitators in the hydrolytic acidification tank, blowers and MBR outlet pumps in the MBR tank. Excuse me, When starting the machine, turn on the blower first and turn off the blower last. Is there any other order? In addition, the MBR outlet pump is the self-priming pump. There is a section of pipe on it. Originally, the water in it is clear, but it has become all black this time. What's the matter?

answer:

1) The opening sequence is generally from front to back according to the process, and the system can generally withstand certain load changes. Therefore, it is OK to open according to the front and back sequence. Even if there is a mistake, the opening sequence can be corrected in time, which is not a big problem.

2) If the water turns black, the general reasons are as follows: (1) lack of oxygen (insufficient overall aeration or sudden increase of influent organic pollutant load) (2) there is a dead corner during normal mixing, and if the dead corner is suddenly stirred, the water body will turn black. 3. There is colored sewage in the influent, which is caused by the system's failure to degrade (low possibility). ‍

Question 32

Pharmaceutical wastewater adopts air flotation + hydrolysis + aerobic process. Recently, the influent concentration is several times higher than the design value, the effluent has been turbid and the COD exceeds the design value. In order to make the water clear quickly, can you add flocculant PAC to the aeration tank (aerobic tank) for forced sedimentation? Or sludge? Reduce do value?

answer:

1. Strengthen aeration instead of reducing do;

2. Stop sludge discharge (before system recovery), and do not increase sludge discharge;

3. If flocculant is added, it can be added in the short term (within 2 days), but not in the long term. Generally, the improvement is about 30%.

4. Please reduce the reflux ratio. ‍

Question 33

Pharmaceutical wastewater adopts air floatation + hydrolysis + aerobic process. Recently, bacteria are cultured. After 3 days of stuffy storm, a small amount of water begins to enter. The water is turbid these days. How to adjust it?

answer:

If sludge is inoculated, this process is normal in the screening stage, but as long as most of the wastewater has ingredients that inhibit microorganisms, a small amount of influent is required to reduce the influent load. It is best to mix some domestic sewage for treatment, or add some substrate concentration that is easy to "digest and absorb". ‍

Question 34

We deal with chemical waste water, high concentration of waste water COD=18000mg/L, after iron carbon micro electrolysis treatment, adjust pH value, flocculation and sedimentation, and low concentration wastewater mixing, COD at 4500mg/l, water 300 tons / day, enter ABR pool treatment (volume 1000 cubic meters), water at COD at 3900mg/l, and then with a small amount of low concentration wastewater mixing. The COD is about 3300mg / L and enters the digestion and oxidation tank for treatment (volume 560m3). The COD of the effluent from the digestion and oxidation tank is about 2000mg / L. after secondary hydrolysis and acidification, it enters the fully mixed aeration tank for treatment (volume 360 m3). The COD of the effluent is about 1600. Now the dissolved oxygen in the digestion and oxidation tank is between 2.8mg/l and 3.9mg/l, the dissolved oxygen in the fully mixed tank is between 4mg / L and 4.8mg/l, and there is little SV30, The sedimentation is very slow, the precipitated water is very mixed, the solution cell has only a lot of nematodes, a lot of bubbles, a small number of clock worms in the mixed pool, and the effluent COD is much higher than the prescribed 500mg/l. How to adjust?

answer:

Whether the wastewater can be effectively degraded by microorganisms needs to be confirmed. The removal rate of general chemical wastewater is not high. You see that the bubble in contact with the oxidation tank is also caused by higher load. The subsequent wastewater entering the mixing tank may inhibit microorganisms, resulting in the inability to improve your MLSS (including active ingredients), and then the effluent is turbid. You can refer to similar wastewater treatment plants around and inoculate the sludge. In addition, it can only be domesticated slowly. But the removal rate should not be expected to be too high. ‍

Question 35

The 1800 m3 pool has 200 tons of water every day, SV is 50%, and the influent concentration is cod5000mg / L, ammonia nitrogen 65mg / L and total nitrogen less than 120mg / L. Effluent cod400mg / L, ammonia nitrogen is basically free, and total nitrogen is less than 30mg / L. Start a 55kW fan. Now there is something different. The influent cod is 7000mg / L, the ammonia nitrogen is 150mg / L, and the total nitrogen is 300mg / L. the effluent quality is seriously deteriorated, the COD reaches 1000mg / L, and the ammonia nitrogen and total nitrogen soar. My emergency measures: increase the aeration volume, increase the dilution of the water inlet in the front section, the water inlet volume does not decrease, and the sludge discharge slows down. The symptoms now appear: the bubbles in the aerobic pond, the mud on the foam and the spray on the side of the pool. Now it is in a complete mess, and the water quality index is still very high. What's the solution?

answer:

1. Obviously, the load of your treatment process is too high for 7000 cod, so it is necessary to reduce the load. Under the condition of ensuring aeration, it is right to reduce the sludge discharge. In addition, the amount of returned sludge can be reduced and the sludge concentration can be further improved.

2. Of course, it would be better if the influent concentration could be reduced. The water dilution can be stopped, otherwise the liquid level load is too high, which will easily lead to the turbidity of the water outlet.

3. If the dilution of influent stops, the reflux can be increased. If it is diluted by the reflux water volume, the total water volume will be stable and the impact can be reduced. ‍

Question 36

Process: primary sedimentation tank - A2 / O - secondary sedimentation tank - valveless filter water volume: Design 10000 tons / day, actual 5000 tons / day. Situation: in 2010, due to various reasons, the cod60 mg / L of influent and 32mg / L of effluent of our plant. However, after the Spring Festival, the water quality of the pond began to blacken on the first day and the white foam (black slag) floating in the aeration tank. On the third day, the whole water surface blackened, the COD inflow tested was 72mg / L, the primary sedimentation tank was 40mg / L, and the outlet was 43mg / L; However, the water quality of all tanks (primary sedimentation tank, anoxic tank, anaerobic tank, aeration tank and secondary sedimentation tank) is black. We think it may be that the influent has changed, which has an impact on the process; During the Spring Festival, the blower was not turned on normally, and the biochemical bacteria died. Seek to analyze the specific reasons.

answer:

If the sludge concentration control before the festival is relatively high and the shutdown time during the Spring Festival is relatively long without necessary aeration, the blackening of sludge is also normal. It is indeed caused by the death of some microorganisms, which can be gradually relieved after influent aeration. The sludge shall be properly discharged to metabolize the dead sludge, otherwise the effluent ss will rise and ignore the generation of new sludge. ‍

Question 37

Our factory is a sewage treatment plant in a textile printing and dyeing centralized Park, with a scale of 30000 tons per day and an influent cod1100 mg / L. the treatment process is regulated hydrolysis tank + primary sedimentation tank + push flow activated sludge process + secondary sedimentation tank + mixed sedimentation tank, cod700 ~ 800 mg / l into the aerobic tank. The aeration system adopts 6 centrifugal fans, each with a flow of 95 m3 / min. the aeration mode adopts hanging chain aerator. The problem now is: the pressure in the pipeline is high, about 0.06mpa, the gas volume is small, only about 50% of the rated (converted into standard condition), and the dissolved oxygen is insufficient. When it exceeds 22000 tons per day, the sludge in the aerobic tank blackens and the effluent becomes turbid. The aerobic tank stays for about 24 hours.

answer:

1. If it happened recently, check whether the aeration head is blocked and whether the aeration pipe is unobstructed. After all, you have high pressure and insufficient aeration. Maintenance can see if it can be modified, such as aeration depth.

2. In addition, the aeration time can be prolonged, such as reducing the reflux ratio and reducing the water inflow (or continuous and uniform water inflow). ‍

Question 38

I deal with printing and dyeing wastewater. Process: regulating tank + primary sedimentation + hydrolysis + contact + secondary sedimentation + sand filtration. Our normal effluent is generally yellow or a little pink, but I don't know why it sometimes appears blue-green. What's the reason? Most of the dyes used are reactive dyes.

answer:

For dye wastewater, as you said, the effluent will change color, which does not mean that if the dye color is only yellow and pink, there will be no wastewater of other colors. After all, the discoloration of various chemicals is also common. ‍

Question 39

Failure of ammonia nitrogen to meet the standard: the failure of process parameters ammonia nitrogen to meet the standard began in mid November. Although it could not meet the standard, the effluent index of ammonia nitrogen basically reached near the marking line. At that time, it was judged that the reasons for the failure of ammonia nitrogen to meet the standard were: 1. High sludge concentration, low influent load and sludge aging; 2. The mud collar was not well controlled. Due to the high sludge concentration, the sludge discharge was strengthened, and the mud collar decreased from about 20 days to about 14 days; 3. The sludge discharge of primary sedimentation is not timely, and the effluent of primary sedimentation is about 30% higher than the inflow index. Then, due to facility maintenance, the water plant was shut down for 10 days in mid and late November and recovered at the end of November. Except for ammonia nitrogen, other indicators have reached the standard within 2 days. So far, the ammonia nitrogen removal rate has gradually deteriorated from 50% to about 30%. Our work has always been aimed at inhibiting sludge aging: the following parameters: sedimentation ratio: about 40%, but the sedimentation in the first five minutes is relatively slow. Do: basically above 4mg / L, flexible control cannot be realized, there is no small power fan, and it is found that the higher do, the lower ammonia nitrogen removal rate without much change in other parameters. SRT: basically controlled in about 20 days. MLSS: basically above 5000mg / L. I don't understand why it is so high. At present, the influent concentration and quantity are not large, and the temperature drops significantly. Influent ammonia nitrogen: basically about 40mg / L, reflux ratio: more than 70%, food micro ratio: basically around 0.06. Microscopic examination: mainly bell worms, rotifers and accumulated insects.

answer:

1. After your system stops running for 10 days, the nitrifying bacteria will be greatly affected. After subsequent recovery, natural non nitrifying bacteria will prevail, resulting in your low ammonia nitrogen removal rate. It is of little significance to increase sludge discharge, which will only accelerate the growth of non nitrifying bacteria.

2. Countermeasures: 1) maintain a longer sludge age than before, such as 25 days, and adjust it to 20 days again after ammonia nitrogen returns to normal. 2) Do not discharge too much sludge at one time, but step by step. 3) Confirm whether the lower pH value is too low? I think as the situation of suddenly stopping processing for 10 days goes away, the system will gradually return to normal. Don't rush for medical treatment. Otherwise, the system will prolong the recovery time. ‍

Question 40

Recently, the COD at the outlet of aerobic tank is less than that at the outlet of secondary sedimentation tank, and the COD is about 100mg / L higher. I don't know what reason, so solve it?

answer:

1. Generally, in the process control, the COD of the effluent from the aerobic tank will not be detected. Is the COD of the aerobic tank measured as mixed liquid or supernatant?

2. If the measured value of the supernatant is lower than that of the secondary sedimentation tank, it indicates that the effluent of the secondary sedimentation tank contains more particles (short hydraulic retention time or poor sedimentation of the secondary sedimentation tank), while the effluent supernatant of your aerobic tank may have sufficient sedimentation time and contain less particles, and the natural detection value will be lower. ‍

Question 41

Some time ago, the ammonia nitrogen in the effluent of our plant (ICEAS process) exceeded the standard. After increasing the aeration rate and stopping sludge discharge for half a month, the effluent can stably meet the standard, but the good time is not long. After stable operation for a week, the effluent TP began to exceed the standard again. After sludge discharge, it can occasionally meet the standard, but it has been repeated. Sometimes the MLSS decreases sharply after sludge discharge, and the effluent TP can not meet the standard stably. There is also the settlement of sludge since December last year has been bad, SV at about 35 MLSS4500mg/l, but always take mud when draining, especially the two days with mud phenomenon is more serious, a drainage began to carry mud, the water is also muddy, low transparency, sludge is also a bit darkened, when the aeration pond bubble is more, yellow white, like grease. What should we do if the effluent quality cannot reach the standard stably?

answer:

I don't know what the F / M is. I think the load is too low. Don't worry about reducing the sludge MLSS too much. The load is guaranteed. Sludge discharge is good for your TP control and the effluent turbidity will be reduced. ‍

Question 42

F / M: 1#0.162#0.093#0.13; There is a doubt that SVI, MLSS and SV are not high, but the effluent is always muddy and the clarity is not high. What's the matter? F / M = qla / xvla = 96mg / LV = 6500m3, q = 9000m3 / d1#mlvss = 1010mg / l2#mlvss = 1640mg / l3#mlvss = 2130mg / L. according to the above data, f / M is calculated as: 1# = 0.13, 2# = 0.08, 3# = 0.06. We are ICEAS process.

answer:

1. Look, there is no low load

2. If the effluent is turbid due to excessive load, please check whether non activated sludge organisms are dominant through the microscope

3, the emergence of foam, depending on your color, may be related to water intake, such as excessive flow of SS; If there are refractory or toxic substances in the water quality (filter out SS and see whether cod increases), it is recommended to reduce the sludge discharge (but do not stop sludge discharge and do not discharge sludge for a long time in future operation). ‍

Question 43

I. food wastewater treatment project, the process flow is oil separation sediment tank - regulating tank - primary sedimentation tank (with built-in honeycomb inclined pipe filler) - primary contact oxidation tank - secondary contact oxidation tank - secondary sedimentation tank (with built-in honeycomb inclined pipe filler) - effluent; The design processing capacity is 10m3 / h. The project is now in the commissioning stage. During the commissioning, the sedimentation effect of the primary sedimentation tank is good, and the primary contact oxidation tank is also good. However, when the water quality of the secondary contact oxidation tank and secondary sedimentation tank turns black, measures such as increasing the aeration capacity and increasing the sludge return ratio of the secondary sedimentation tank are taken, but the effect is not good. How should it be solved?

answer:

Or the treatment water is discontinuous, and the residence time or static time is too long. The COD of influent is not stated, so it can not be judged whether it is caused by too high influent load. ‍

Question 44

Process: coarse and fine grid, cyclone sedimentation tank, improved oxidation ditch, sedimentation tank and clean water tank. Commissioning: July 28: inlet and outlet water quality pH: 7.47, 7.76; Chromaticity: 35, 40; COD：185mg/l，119mg/l； Ammonia nitrogen: 82.470mg/l, 44.715mg/l; SS：1072mg/l，828mg/l； Total phosphorus: 4.398mg/l, 3.789mg/l; Petroleum: 0.769mg/l, 0.439mg/l; Total nitrogen: 96.505mg/l, 74.060mg/l; Anionic detergent: 0.114mg/l, 0.070mg/l; Fecal coliform: 44974183; July 30: pH of inlet and outlet water quality: 7.51, 7.76; Chromaticity: 43, 40; COD：213mg/l，119mg/l； Ammonia nitrogen: 76.578mg/l, 44.715mg/l; SS：1035mg/l，828mg/l； Total phosphorus: 4.218mg/l, 3.789mg/l; Petroleum: 0.713mg/l, 0.439mg/l; Total nitrogen: 68.319mg/l, 74.060mg/l; Anionic detergent: 0.249mg/l, 0.070mg/l; Fecal coliform: 35002219; In the result No. 28, chromaticity: 35, 40; The inlet water is lower than the outlet water. In the results of No. 30, total nitrogen: 68.319mg/l, 74.060mg/l; The inlet water is lower than the outlet water. Why?

answer:

In terms of water quality, the following aspects shall be considered:

1. There is residence time in the system, that is, the high load substances in the previous few days stay in the system. Although the influent load is low these days, the average value in the system is not low

2. Some pollutants decompose, resulting in the increase of chromaticity.

3. Improper control of biochemical system will lead to the deterioration of microbial decomposition and sedimentation, and also lead to the increase of chromaticity. ‍

Question 45

Why do most printing and dyeing plants have yellow effluent? I have been to many printing and dyeing plants with the company salesman, and the treatment facilities of these plants are relatively perfect. Most of them are physicochemical treatment first, followed by hydrolysis acidification, followed by aeration tank (some are fully mixed aeration, and some plants have hung membrane), followed by secondary sedimentation tank and sand filtered water.. Even if decolorizing agents (cationic and quaternary ammonium salt products) are used, this phenomenon will still occur. Some people say that iron salt is used, but some manufacturers treated with aluminum salt also have this phenomenon. The effluent is transparent, that is, it is yellow, which is not caused by more suspended solids in the effluent.

answer:

1. Some pigments in printing and dyeing wastewater can not be biodegraded and adsorbed, and naturally it is not easy to be physically and chemically removed. Not all colors of decolorizer can be removed, so the color of effluent is normal. Moreover, when your system is abnormal, such problems are more likely to occur.

2. As a microorganism, the non degradable coating can not be removed even after adsorption, and will eventually be released back to the water body. ‍

Question 46

Cod is about 200-300mg / L, and a few are less than 200mg / L. the aeration equipment here always fails. The only thing is that the dissolved oxygen rises after the sludge concentration decreases. What is the sludge concentration? What is the dissolved oxygen value to increase the inflow? There was no sludge discharge yesterday. Today, there are many sludge flocs in the outlet water of the sedimentation tank, and the whole outlet water is turbid. How to adjust it?

answer:

1. According to your influent COD concentration, it is obviously too high to maintain the sludge concentration of 10000 before. The consequence is that there are many invalid components in the activated sludge, low impact resistance and many floating particles in the effluent.

2. In the later stage, you reduce the sludge concentration, the original relative balance is broken, and the fluctuation of treatment efficiency is normal. In addition, if the water temperature decreases, the treatment efficiency will be further reduced. I want to maintain the current sludge concentration for a period of time, the microbial will adjust the new balance, and then it will tend to be normal. However, in the later stage, attention should be paid to the problem of sludge discharge. Do not control excessive sludge concentration.

3. Dissolved oxygen is not a big problem in winter. ‍

Question 47

In the contact oxidation + fully mixed activated sludge process, there is no dead sludge, but the effluent ammonia nitrogen has also increased, from 15mg / L to 95mg / L, and the cod has also increased from 450mg / L to 750mg / L. now there is no scum in the sedimentation tank, but the effluent ammonia nitrogen is high, the COD is high, and the phosphorus is 1.5mg/l. How to adjust?

answer:

1. The denitrification effect of this process is poor, and denitrification is mainly completed by contacting the anoxic part in the oxidation biofilm. In this case, the treatment effect is poor.

2. In addition, when you do come out, check whether it is appropriate. Before you come out, increase the aeration rate. ‍

Question 48

It's just that there is no production on Sunday, but the sewage treatment station has been stuffy exposed all the time, but the effluent is particularly poor on Monday every week, and there are a lot of suspended solids. What's the reason?

answer:

Because of the exposure. It is already a stable system, so there is no need for stuffy aeration. Otherwise, the sludge will be de flocculated and the effluent will be turbid. ‍

Question 49

We treat domestic sewage. Our influent is now cod200mg / L, the sludge concentration is controlled at 2200mg / L, and the do is controlled at 2.5mg/l. The floc of sludge is relatively small, and the effluent quality has been yellow, but the COD is below 50mg / L?

answer:

The main reason is the low load, but it doesn't matter if you are stable. Just pay attention to energy consumption at ordinary times. If you can save it, try to save it as much as possible. ‍

Question 50

There are red nematodes in the disinfection pool. What's the reason? Moreover, the effluent is white, ammonia nitrogen PCOD and other indicators are qualified; Is there more grease wastewater, or there are more organics that are difficult to explain biochemically, but the effluent COD is up to the standard.

answer:

Filter with filter paper. If the filtered water is clear, it indicates that it is insoluble particles, otherwise it is soluble. Usually, after demulsification of oil wastewater, the water quality is white. Your analysis also makes sense. ‍

Question 51

When the aeration of the contact oxidation tank stops, the whole tank is very turbid. There is very fine mud in the middle of the upper water. There is no film hanging filler at all, which was seen before. I don't know why? At the beginning of the year, when the flour was stuffed and slowly aerated, it had not been well for more than a month now. There was still a dull white foam in the oxidation pond just like the foam when it was aerated with flour at that time, but not so much.

answer:

There are probably two possibilities of turbidity:

1. Activated sludge grows in the contact oxidation tank. This will happen if there is reflux. Then there will be mud film symbiosis.

2. The influent contains a lot of particulate matter, especially inorganic. If there is no sludge discharge, or the sludge discharge and discharge can not keep up, it will accumulate, resulting in turbidity during aeration. ‍

Question 52

The COD of our plant's influent is about 75mg / L, bod30-40mg / L, and the COD of our effluent is about 60mg / L, bod8-10mg / L. why can't our effluent COD be about 30?

answer:

1. Biochemical treatment of wastewater with low organic concentration is indeed difficult, because it is not conducive to the increase of activated sludge. As a result, the flocculation of activated sludge is reduced. In addition, the sludge is easy to age, resulting in the increase of fine particles in the effluent, the deterioration of the effluent and the reduction of organic matter removal rate.

2. We can look at the COD after effluent filtration. If it is lower than 30, we can consider strengthening the low ss of effluent, such as increasing filtration. In addition, the concentration of activated sludge should also be reduced. ‍

Question 53

A Baijiu liquor brewing wastewater is divided into two systems and adopts the same process. Due to the poor operation of one system aerobic tank some time ago, the sludge becomes very small, and the sedimentation ratio is only about 1%. During aeration, the tank water is black, and the effluent has fishy smell. The operation of the other system is normal. The outlet water of the two systems is in one outlet tank, and the detected cod is about 30mg / L. What is the fishy smell of aerobic effluent?

answer:

The effluent has fishy smell, which may be as follows:

1. The effluent contains fine activated sludge, resulting in the taste of activated sludge being carried out by the effluent.

2. The sludge itself has fishy smell, so it is generally a normal phenomenon.

3. As you said, due to system failure, a lot of sludge runs out. If it is recovering now, the sludge is in the culture growth period with high activity, which will inevitably flow out with the effluent.

4. The influent contains fishy smell, resulting in fishy smell in the effluent. ‍

Question 54

The effluent index is up to standard. But the water is still muddy. For urban sewage plants, BOD / COD value is low. Anyway, the influent is complex (including coking plant). Cod is low, N2H4 is high, q is low, and water is extracted intermittently. Process: hydrolytic acidification anaerobic anoxic Carrousel oxidation ditch 2000 secondary sedimentation tank (sludge reflux) - flocculation (homogenization tank) - designed effluent inlet q = 3W, COD = 500mg / L, N2H4 = 35mg / L, SS = 400mg / L, effluent COD = 60mg / L, N2H4 = 8mg / LSS = 20mg / L, actual inflow 8000, COD = 200mg / L, N2H4 = 40, SS = 150mg / L, effluent COD = 130mg / L, N2H4 = 20mg / L, SS = 110mg / L and pac200mg / L, Effluent COD of flocculation tank = 40mg / L, ammonia nitrogen = 5mg / L. situation of biochemical tank: SS = 3500mg / L, VSS = 1500, SV30 = 8 / 100. Solution: 1: now the medicine is added, and the effluent index meets the standard. But the water is still muddy and not clear. What's the reason and what to do. 2: Help me look at the mud in my biochemical tank. Is there any problem.

answer:

According to your influent load, the sludge concentration is too high, especially the active ingredient is very low, so sludge discharge and replacement is very important. ‍

Question 55

Activated sludge has been entrained in the effluent for a week. Can the dosage be added according to the original quantity? Part of the aeration tank contains the foam of the sludge, and the color is brown. How should I adjust it now? Should I adjust the dissolved oxygen value?

answer:

With the increase of water, the concentration of organic matter should also increase, so your glucose can not be added or halved. Aeration is generally too much, which can be reduced appropriately, especially when there is no water inflow, it must be stopped (at most, stop the water inflow and then aerate for 1 hour). Because your effluent contains activated sludge, even if the water volume increases, the sludge concentration decreases. I think the system will adjust over a period of time (that is, the sludge concentration will adapt to the influent organic concentration).

Question 56

We have mainly aluminum alloy cleaning wastewater and stainless steel processing wastewater,

The pH is about 6. The previous physicochemical and A2 / O processes are adopted. The influent cod is about 400 ‰ / L, ammonia nitrogen is 30 ‰ / L and total nitrogen is 50 ‰ / L. at present, the existing problem is that the effluent ammonia nitrogen and total nitrogen exceed the standard, and there is no nitrate and nitrite in the biochemical tank. Is it the influence of pH and heavy metals.

answer:

Ph6 is too low, preferably above 7.2. In addition, this kind of wastewater is generally difficult to degrade organic matter, so it may be necessary to supplement some carbon sources. Considering economic factors, you can gradually add it from small to large to observe the effect.