Water World (WeChat: chinacitywater) Introduction: Sludge aging, it is easy to judge, this time urgently need to adjust the age of sludge, biochemical system sludge needs to be replaced, otherwise it will fluctuate out of the water. I have also shared with you about sludge expansion, disintegration, poisoning, and aging. As the saying goes, knowledge needs to be learned from the past to understand the true meaning.
Sludge aging
A probe into the key points of sludge aging judgment
The aging phenomenon of activated sludge is common in the aerobic biochemical system currently in operation, and the aging of sludge is the same as other sludge traits, which also affects the quality of effluent water. First of all, let's take a look at what are the key points of judgment on sludge aging.
1. Performance of activated sludge sedimentation ratio
1) Activated sludge settlement rate. Usually in the activated sludge sedimentation ratio experiment, it can be found that the aging sludge can complete the sedimentation process in a relatively short time. In general, the sedimentation rate of sludge in other stages is about 1.4 times faster than that of non-aging sludge.
2) Activated sludge flocculent size. Aged sludge flocs are large but looser.
3) Activated sludge color. The color of the aged sludge appears dark, gray-black and does not have a fresh luster.
4) Supernatant clarity. After aging, the sludge is easy to disintegrate, so there are more small flocs that are free in the water body, but the gap between the flocs can maintain a better clarity.
5) Liquid level scum. Aging activated sludge can cause some bacteria to die, and the decomposed bacteria will be aerated and dispersed and adhere to the bubbles to produce foam or scum.
2. Observe the change of sludge through the microscope
Generally, when the activated sludge ages, it is usually based on the number of offspring animals that dominate, and the large number of offspring animals can be used as an indicator of sludge aging. In addition, the status of the activated sludge bacteria is observed, and generally in the case of the aging of the activated sludge, the bacteria and micelles appear coarse and dark.
3. Confirmation of the food micro ratio
Usually occurs or may occur in the case of activated sludge aging, the food micro ratio is in or for a long time in a low level, especially when the food micro ratio is less than 0.05, the probability of activated sludge aging is very large.
Second, look at the aging of the sludge in the scene
Actual water treatment in the process operation, usually can be judged according to the above points, it is true that due to the difference in water quality and the industry involved, in the analysis and judgment of sludge traits can not be generalized, so on the theory, the accumulation and summary of experience is particularly important.
The following are the sludge aging phenomena that occur in actual operation and the microorganisms seen in microscopy.
1. Appearance:
Aeration tank foam, the fine sludge after aging desuffling, will float on the surface of the foam, and the foam that should obviously be whitened will become abrupt, gray or black.
Aging sludge color and properties
This kind of foam, after taking it up with a tool, as long as the foam dissolves, the rest is fine sludge, very fine, very fine.
Finely crushed aging sludge
2. Microscopic examination
Microscopic examination will reveal many progenitorous animals with signs of aging, such as phosphorus shell worms, epidermal worms, nematodes, etc.
Phosphorus shell worm
Water World (WeChat: chinacitywater) learned by consulting relevant information that when the activated sludge ages, the number of inactive sludge protozoa and protozoa will increase.
1) Side jumper
The presence of side jumpers is often related to high loads, but in actual operation, it can be found that in the case of extreme aging of activated sludge, there will also be a large increase in side jumpers, which is mainly related to the presence of free bacteria in the sludge, which comes from the activated sludge of deflocation.
Side jumpers
2) Shell worms
The occurrence of activated sludge aging corresponds to the high probability of the occurrence of epidermal worms, and the shell worms often show a slight tan color, which is different from the transparency of the proliferation of simple low-load shell worms.
Shell worms
The epidermal worm dies
Why is it said that the appearance of epidermal worms and phosphorus shell worms means aging? Water pollution engineers who have been engaged in industrial wastewater treatment for 10 years pointed out that the aerobic tanks that appear shell worms have signs of aging, where there are fine fragments of sludge, the measuring cylinder is suspended, the second sinking pool drifts with the water, and the naked eye can see the foam on the surface, this situation is done by microscopy, it is easy to see the shell worms.
In some projects, microscopic examination shows that the sludge is aging or subjected to toxic substances, and the epidermis can easily die. In the project with foam done by the water sewage division, the sludge is aged to the point that it can no longer age, the entire lens does not have a single living object, a large number of shell worms die, and the sludge settlement ratio can reach 60% in 5 minutes, and 30 minutes can reach 50%.
Living Shell Worms (Transparent) & Dead Shell Worms
The above case worm microscopy pictures are all seen by water pollution engineers when treating industrial wastewater, and the COD of the aerobic tank is generally 700-1000mg/L, and even more than 2000mg/L have dared to enter the water.
Due to the low load, a large number of shell worms are more common in municipal sewage plants, at the same time, the load is low, the sludge activity is better, the fixed type, the epizoans, the protozoa are there, the algae are also many, the microscopic examination is relatively rich; the effluent water quality is relatively stable.
3) Nematodes
The appearance of nematodes in epizoans is also one of the signs of aging. Its manifestation is usually at the beginning stage of sludge aging, and when the aging of activated sludge enters an accelerated period, the phenomenon of nematodes dominating in post-animals is difficult to see.
nematode
4) Rotifers
As far as rotifers are concerned, among the common rotifers, saddle beetles and rotifers, the latter two types often show the negative impact of the operating state of activated sludge, and in terms of sludge aging and flocculation, the signatory of rotifers is stronger.
Rotifers
Water friends with relevant practical experience believe that the strongest evidence of sludge aging is SRT. Rotifers are precursors to sludge aging, and the emergence of rotifers is more frequent at the same time as bell worms and tired branches.
When performing industrial wastewater microscopy, there are almost no indicator organisms, generally high loads, and living organisms cannot survive; toxicity and excessive aging are three reasons.
Let's take a look at the aging of activated sludge in a group of domestic sewage treatment.
Pure domestic sewage, the treatment scale of 30000m3/d, the use of oxidation ditch process. The sludge is aging, and you must not have seen it running to this state. It is related to aeration and push flow, and there is more foam at the end.
Biochemical pool foam
Microscopic microorganisms are abundant, including a large number of shell worms, but many have died. Raw water into the oxidation ditch COD 400mg/L, effluent 50mg/L.
A variety of protozoans coexist
The sedimentation ratio is 35%, there are many particles suspended in the water, fine fragments, the water is very clear, and the water on the surface of the measuring cylinder will have floating debris.
Aging sludge settling ratio
In addition, maned caterpillars are also prone to occur when the sludge is aged and defluded.
Mane caterpillar
Water friends share:
Printing and dyeing wastewater in industrial wastewater, the COD of the AO pool is about 1200mg/L, and the effluent is about 300mg/L. The COD load is less than 0.1, not to mention the BOD, basically no sludge discharge, and the sludge aging is serious. The most common thing seen in the previous microscopy is the wandering servant worm.
Wandering worms
Sludge aging, every day there are large bubbles and a small amount of mud flakes, inlet water COD230mg/L, ammonia nitrogen about 17mg/L, pH about 7.5; effluent COD39mg/L, ammonia nitrogen 0.3~0.8mg/L. On microscopy, black sludge appeared in the SBR pool. The main reasons for the analysis are that the sludge is long, the concentration is high, and the stirring strength is not enough; therefore, it is necessary to take measures to increase the aeration capacity, increase the amount of sludge discharge, and remove or fish out the surface scum in time.
SBR pool aging sludge
Aging sludge
Microscopy
Copyright notice: Please indicate the source, author; water world subscription number; WeChat ID: chinacitywater. If you do not add the source and author, you will do a plagiarism report!
Welcome to follow the water world subscription number: chinacitywater or download the water world community APP to get it.