What causes pin floc in clarifier?
Pin-floc is also associated with denitrification in the clarifier. Bacteria convert the nitrate to nitrogen gas and the resulting bubbles buoy floc particles to the surface. Pin-floc also occurs in systems where solids are unintentionally being returned from solids processing.
What is pin floc in wastewater?
Pin floc can be described as small, weak flocs that are subject to flotation within the clarifier. Pin floc leads to a more turbid effluent. It is most commonly the result of exceedingly high sludge age. Reducing sludge age often minimizes the occurrences of pin floc.
What type of waste is sludge?
It mainly accumulates in sewage treatment plants and is a by-product of treatment processes. This is typically what sludge is, but in definition terms, sludge is that semi-solid slurry of waste or residue that accumulates at the bottom of treatment plants, mostly sewage treatment plants.
What is floc in activated sludge?
Activated sludge flocs are a flocculated mass of microorganisms, extracellular polymeric substances (EPS) and adsorbed organic and inorganic material. The results indicate that the EPS, both in terms of quantity and quality, are very important for the floc properties of the activated sludge.
How do I control bulk sludge?
Control of low F/M bulking is by reducing the aeration basin MLSS concentration and increasing the F/M (manipulating the “M” component). Lowering the MLSS concentration may not be suitable for many plants as this may cause the loss of nitrification and increase waste sludge production.
Which are the three ingredients in activated sludge system?
Which are the three ingredients in activated sludge systems? Explanation: The cells need oxygen for their metabolism, air is injected from the bottom of the aerator. The water is well agitated by the rising bubbles and creates good contact between the three ingredients: cells, sewage and oxygen.
How do you control MLSS?
The typical control band for the concentration of MLSS in wastewater is 2,000 to 4,000 mg/L for conventional activated sludge, or up to 15,000 mg/l for membrane bioreactors. One of the easiest control procedures for activated sludge systems is the Constant Mixed Liquor Suspended Solids method.
Which is the first step in the sludge treatment process?
Thickening is usually the first step in sludge treatment because it is impractical to handle thin sludge, a slurry of solids suspended in water. Thickening is usually accomplished in a tank called a gravity thickener. A thickener can reduce the total volume of sludge to less than half the original volume.
What is the purpose of sludge return in activated sludge treatment process?
The purpose of Return Activated Sludge (RAS) is to prevent loss of microorganisms from the aeration tank and maintain an adequate population for treatment of the wastewater. As microbes metabolize their substrate, they grow and multiply in number.
What is a major cause of repeated sludge bulking?
The main cause of sludge bulking is the growth of filamentous bacteria. Filamentous microorganisms grow in long strands that have much greater volume and surface area than conventional floc and are very slow to settle.
What is a pin floc in activated sludge?
Pin-floc in activated sludge may be defined as very fine floc particles with poor settling characteristics. Pin-floc/deflocculation may be assessed through visual observation: Carryover of very fine material in final effluent Turbid or milky appearance of final effluent
Which is the best description of a pin floc?
Can a pin floc cause a dispersed growth problem?
are <50um in diameter. Pin floc occurs most commonly at starvation conditions — a very low F/M and long sludge age. Chronic toxicity can also cause a pin floc condition. Free floating filaments can, at times, cause a dispersed growth problem.
What to do about pinfloc in raw wastewater?
Check available records for the presence of toxic substances in the raw wastewater. Correct the relevant adverse factor. If a tendency to pin-floc/deflocculation persists at a low level addition of a settling aid (e.g. polyelectrolyte) may be required.