[Energy people are watching, click on the top right corner to add 'Follow']
1. Case background
Recently, due to engineering renovations, production was stopped for about 20 days. Decarbonization process, aerobic aeration method used in the surface exposure, because the leader believes that the aeration shutdown will cause the sludge to sink to the bottom, so the aeration can not be stopped during the suspension of production.
2. Discontinuation of production
Before the suspension of production, the performance of the sludge floc condensation group is not bad, a small number of filamentous bacteria, bell worm activity is better, there are fewer biological bubbles in the body, and the mouth circumference is slightly larger. Comes with pre-production microscopic inspection.
Bell worm genus: Bell worm, partially shrinking the body of the worm by the tail stalk. It is characterized by muscle filaments in the caudal stalk, unbranched, and individually fixed to the floc. The caudal stalk is mostly straight, but sometimes curled into a spiral.
After the well-treated flocculents are firm, the first fimbriches that appear are bellworms. The environment in which bell worms appear varies from species to species, and the treatment status can be judged according to the ratio of the size of the mouth to the width of the cells. Insects with a small ratio of mouth and circumference to cell width appear in the period of becoming good or tending to disintegrate from a good period. A large ratio of the orifice to the width of the cell appears at the best stage. When the solid ciliates represented by bell worms are used as dominant protists, the effluent water quality is good and clear.
From September 22, the workshop water gradually reduced, in accordance with the requirements of the leadership to treat part of the workshop refractory water, 23-26 days a day small flow of water about seven or eight hundred square meters, the night shift will be part of the filter press feed water to the materialization system, so that the middle and night shift has a small amount of water overflow into the biochemical system. No additional carbon sources were invested during the note period. After all, the production stopped, no matter how much wastewater can also be treated, by the 26th there is not much water stored, just notify the materialization system pH fine-tuning is almost on the line, reduce the removal rate of physicochemical to improve the biochemical inlet COD.
Attached to the 26th microscopic photo, the flocculation of the sludge decreased, there was a slight disintegration, at this time the amount of mud discharge was small, and the number of rotifers increased significantly.
Rotifers: In sewage, they mainly feed on suspended particles and gelatinous matter, breathe through the osmotic action of the epidermis, and have a prosthetic cavity between the body wall and the digestive tube, which contains liquid and various internal organs. It has a wheel-like arrangement of cilia for predation and movement, and the activity is more frequent and intense.
The appearance of rotifers in the activated sludge during the culture period indicates that the sludge is basically cultured and mature; the presence of a large number of rotifers during operation may indicate that the sludge will expand. Long-term aeration of excessive sludge aging will also appear a large number of cavityless rotifers.
By the 27th-30th, despite the reduction of the materialization removal rate, the effect was still not good, the daytime water flow was only about four hours and the COD was only more than 20 mg/L (decarburization process), and the surface exposure to maintain the minimum speed OF THE WAS had been increased to 8-10mg/l. On microscopic examination, the microorganisms disintegrate significantly, the bacterial gel mass is loose, and only rotifers and shellworms are found.
On October 1-4, the leaders instructed to add glucose, which is about 50 ppm of the pool capacity. Of course, it is not only a good thing, the bad thing is that no one in the workshop is inspected and repaired during the statutory rest day, and there is no raw material flushing water brought by inspection and maintenance; during the four days, a submersible pump is added to the initial sinking tank and slowly mixed into biochemical.
However, even the rotifers are gone in the post-mirror examination of the carbon source, and I am also a little panicked, perhaps under such a high DO, it is difficult for microorganisms to grow, after all, THE DO is 10 mg/l. At this time, the microscopic examination has completely no active microorganisms, not even rotifers, and there are filamentous bacteria. High SV, poor sedimentation performance, many fine particles of supernatant, water temperature 18 °C. With a microscopic examination photo, the sludge disintegration is serious, and the microorganisms are only shell worms.
Epidermal worm genus: when the activated sludge load is low and the sludge residence time is too long, it appears in large quantities, and carabula and phosphorus shell worms often appear when the sludge disintegrates.
3. Resume production
Microscopic examination before resuming production also basically disintegrated, and microorganisms were mainly shell worms.
Production resumed on the 13th, of course, the amount of water in the early stage was small, but the concentration of residual raw materials was not low, of course, this is not entirely a bad thing. At this time, the color of the water is very poor, grayish white, and you can see the mud flowing out. At this time, the concentration within the biochemistry is low and the temperature is low. After the water inlet, the SV straight line lowered the leader panicked, and after adding activated carbon, a small amount of continuous sludge SV was basically stabilized, and the color of the water in the second sedimentation pool was gradually clear.
15-16 days have been restored clock worms, during this period glucose did not stop, N.P's amount of amplification, since the leader did not say stop the carbon source I do not need to ask, DO outlet reduced to 6 mg / l, water temperature is gradually restored to 32-35 ° C.
Attached to the microscopic photo, there are bell worms, the stomach is hollow and empty, and the disintegrating fine particles can still be seen.
18-20 days to resume production for a week, although in a low load state, but obviously much better than before, DO3, SV60. Microscopic examination of the twigs.
Branch worms: When the water quality is well clear and the water is clear and transparent, it appears at the same time as bell worms, cover worms, rotifers, etc., and the tired branch worms appear in large numbers and may tend to disintegrate.
4. Summary
Excessive aeration, excessive oxidation of activated sludge, and the discharge of the second sedimentation tank with more unsettled particles flowing out. When doing sludge settlement, it is possible that the activated sludge is not settled or suspended in the water body after flocculation, and the compressibility becomes worse. For such low-load operation, intermittent aeration is recommended.
Disclaimer: The above content is reproduced from polaris power news network, and the content sent does not represent the position of this platform.
National Energy Information Platform Tel: 010-65367702, Email: [email protected], Address: People's Daily, No. 2 Jintai West Road, Chaoyang District, Beijing