Practical summary of sludge culture and domestication!

How to shorten the time of sludge culture and domestication and reduce the problems prone to occur in the process, from the sludge dodging, debugging and the full load operation of the designed wastewater, to ensure the normal operation of the aerobic biochemical facilities.

1. Preparatory work

1.1 Check before commissioning

Whether the oil quality and oil level of the blower are in 2/3 of the sight mirror, rotate the fan to the drum, check whether it is normal, and start the fan to run if there is an abnormal sound. Whether the aeration disc of the aeration device is broken and tightened, whether the pipeline has gas leakage and whether the operating equipment is normal. Check the completion data of the biochemical tank and the preparation work such as cleaning and leak test.

1.2. Material preparation

1.2.1. Sludge preparation

a. Aerobic biochemical sludge is calculated according to 4-6g/l dry sludge, if the amount of dry mud added to sewage with good biodegradability (food, meat processing) can be taken as a low value, and the amount of sludge added to wastewater with poor biodegradability (chemical and pharmaceutical, coking, paper making, electroplating, etc.) or high cod, high ammonia nitrogen wastewater can be taken as a high value, or even a little more.

Biodegradability According to the ratio of BOD/COD can judge the degree of difficulty, generally speaking, when the ratio is greater than 0.45, indicating that the sewage is relatively easy to biochemical, between 0.3-0.45, indicating that the sewage can be biochemical, when the ratio is between 0.2-0.3, indicating that the sewage is difficult to biochemical, when the ratio is less than 0.2, indicating that the sewage is not biochemical.

b. It is possible to use the same wastewater or similar wastewater sludge as much as possible, which can reduce the time of sludge culture and domestication.

c: Adding municipal wastewater sludge requires the cultivation and domestication of sludge. The amount of sludge added is calculated according to 85% moisture content: if the aerobic biochemical tank is 500M3. Dry sludge 500*5kg=2500kg, a ton of wet sludge containing dry sludge 1000* (1-85%) =150kg, then 500M3 biochemical tank needs 17 tons of wet sludge.

1.2.2. Preparation of auxiliary materials

Carbon sources (glucose, flour), urea, potassium dihydrogen phosphate, caustic soda, etc.

Nutrient ratio: The ratio of carbon, nitrogen and phosphorus in wastewater in ordinary carbon removal process, BOD: N: P=100:5:1. The carbon and nitrogen in the nitrification and denitrification process is controlled at COD: NH3-N=4-6. (Not explained here)

The equivalent of each nutrient:

Glucose added into carbon source (chromium method) : 1g glucose can be converted into 1.06g COD Methanol added into carbon source: 1g methanol can be converted into 1.5g COD Flour added into carbon source (chromium method) : 1g flour can be converted into 1.1gCOD. The addition of brown sugar is converted into a carbon source: 50% of the total sucrose, 1g of brown sugar can be converted into 0.5gcod. Conversion of urea into nitrogen source: add 1g N source, need to add 2.14g of urea potassium dihydrogen phosphate into phosphorus source: Add 1g P source, need to add potassium dihydrogen phosphate 7.35g superphosphate is not recommended: calcium increases the hardness of water, and is slowly dissolved in water. Superphosphate is not recommended: calcium increases water hardness and dissolves more slowly in water.

1.2.3. Instrument preparation

Dissolved oxygen tester, 1000ml cylinder, PH meter (broad spectrum test paper) microscope, etc

1.2.4. Make running records

Develop the biochemical operation record book, and make a good record in the operation process.

2. Debugging of sludge culture

2.1. Natural culture method

Also known as direct culture method. It is a culture process that uses a small number of microorganisms in the wastewater and gradually propagates. The culture process is also a process in which microorganisms gradually adapt to the nature of wastewater and obtain domestication. As the culture cycle is too long, in the early operation process due to less mud production, can not reach a certain sludge concentration, fewer microorganisms, resulting in too light sludge load and other factors, resulting in substandard effluent. Therefore, the natural culture method is not recommended because of its poor applicability.

2.2. Inoculation of sludge with bacteria

With short culture time and quick effect, it is a common method for activated sludge culture and acclimation. Suitable for all kinds of industrial wastewater treatment. The principles of activated sludge acclimation should be gradual, targeted, carefully controlled, correctly judged and scientifically summarized.

2.2.1. Sludge dosing

First fill the biochemical tank with wastewater or three-quarters of the volume of the tank (clean water: sewage =1~2:1, if conditions can be directly added water), the inoculation sludge dosage is calculated according to 5% of the volume of the tank dry sludge. Sludge dosing is generally used to add sludge to the residual sludge tank and pump it to the biochemical tank by sludge submersible pump.

2.2.2. Smothering

a. After the sludge is added, open the blower for dull aeration. The purpose of dull aeration is to activate dormant microorganisms. Requirements: After the microorganism is activated, there is no need for stuffy aeration, that is to say, the sludge appears floc, otherwise excessive aeration will cause excessive oxidation of activated sludge, and finally make activated sludge self-decomposition and death. The dissolved oxygen is controlled at 2~4mg/L.

The time of stuffy aeration is 2~3d until the sludge is exposed and dispersed, the dissolved oxygen content is controlled, the air volume is controlled with the fan frequency conversion speed or the air is opened and emptied, and the size of the aeration is observed to be uniform, and the local aeration cannot be large. Nutrient dosing, analysis of detection indicators. The temperature is room temperature. Pay attention to observe the change of sludge floc, sedimentation ratio (SV30) can be observed, the water quality may still be a little cloudy, the color of sludge floc is still a little black, the flocculation size is different, but it can settle.

b. after the completion of stuffy exposure, you can take 10 to 12 hours for a period of stuffy exposure, stop exposure. Stuffy exposure time 8-9 hours, stop exposure 3-4 hours, aeration, stop exposure is an alternate process of disgust, good, contribute to the growth of sludge bacteria. It is also a factor to prevent excessive aeration, while enhancing the settling performance of the sludge floc, helping the formation of bacterial micelles, and increasing the activity of the sludge. The period is 3-4d. Pay attention to observe the water quality, sludge system settling performance, the general water quality appears transparent and clear, the sludge gradually turns yellow brown, the settlement rate is faster.

c. After the end of the stuffy and shut down cycle, the bacteria can be cultured and acclimated by means of stuffy, shut down and water intake, and the cycle time is 12 hours, that is, 4-4-2 method. Stuffy exposure for 4 hours, water intake for 4 hours (the water intake is 50% of the design), stuffy exposure for 2 hours, stop exposure for 2 hours, and gradually adjust the water intake mode, 5-5-1 that is, stuffy exposure for 5 hours, water intake for 5 hours, and stuffy exposure for 1 hour. Stop exposure for 1 hour, 3-5 days for a small cycle. Until six hours of exposure, six hours of water. According to the operation situation, pay attention to observe the water quality, settlement ratio, control the dissolved oxygen, detection indicators, etc., carry out microscopic inspection 1-2 times a day, and the shape change of the bacteria micelle. If the secondary sedimentation tank is full of sewage, the reflux ratio can be 100% of the controlled water intake. The common secondary sedimentation ponds are vertical flow, deflected inclined tube, radial flow, flat flow and so on. The removal rate of detection indexes was above 50-60%. The total time required for the above cycle is about 12d.

d. Enter the stuffy exposure, each six hours of water, the whole biochemical system runs normally, the water is stable, you can reduce the stuffy exposure time as a period of about 2d, gradually increase the inlet time, reduce the stuffy exposure time, until the stuffy exposure is stopped, and the water is injected for a long period. The water quality of the incoming water must be stable, and it must not be high and low and changeable. It is best to enter the conditioning wastewater after pretreatment into the conditioning tank. The dosage of nutrients can be appropriately reduced according to the operation condition, and the control of dissolved oxygen is 2-4mg/l. Control the sludge load 0.3-0.5kg/(kg.d), the remaining sludge should be discharged regularly, pay attention to the discharge. Ensure that the sludge concentration is about 4-5g/l, and often detect SV30 and microscopic examination. It takes about 10d.

2.2.3. Load lifting

After the end of the shutdown, the water intake is 50% of the design, the continuous water intake can be increased by 10%, and the reflux ratio is also adjusted until the designed water is operated at full load. First of all, it is necessary to ensure the normal biochemical operation, the effluent of the secondary sedimentation tank is up to standard, and the biochemical indicators are strictly implemented and controlled. Do frequent observation, frequent detection, frequent brain, careful operation. It is best to adjust the water intake ≥2d, and it takes about 10d.

2.2.4 Full load operation

The sludge culture and acclimation reach the final full load, and the reflux ratio can be increased to 1.5-2 times of the water intake. The results of operation depend on our usual accumulated experience, so we must strictly implement the operating parameters of activated sludge to guide.

Biochemical aerobic tank normal operation, if there is a long time to stop water, start water according to 60% of the design amount of water, about 6 hours by 20% liter load, until full load operation.