Table of Contents
What is meant by activated sludge process?
The activated sludge process is a means of treating both municipal and industrial wastewater. The activated sludge process is a multi-chamber reactor unit that uses highly concentrated microorganisms to degrade organics and remove nutrients from wastewater, producing quality effluent.
What is activated sludge process explain with diagram?
In activated sludge process wastewater containing organic matter is aerated in an aeration basin in which micro-organisms metabolize the suspended and soluble organic matter. Part of organic matter is synthesized into new cells and part is oxidized to CO2 and water to derive energy.
Which is better trickling filters or activated sludge?
Although trickling filters are more easily operated and consume less energy than activated sludge processes, they have a lower removal efficiency for solids and organic matter, they are more sensitive to low air temperatures, and can become infested with flies and mosquitoes (UNEP et al. 2004).
Does activated sludge have aerobic bacteria?
Activated sludge (AS) is composed of aerobic and anaerobic microorganisms such as bacteria, archaea, fungi, and protists. It is capable of degrading organic compounds, including petroleum products, toluene, and benzopyrene (Seviour and Nielsen, 2010).
Why sludge treatment is required?
Treatment and disposal of sewage sludge are major factors in the design and operation of all wastewater treatment plants. Two basic goals of treating sludge before final disposal are to reduce its volume and to stabilize the organic materials. Smaller sludge volume reduces the costs of pumping and storage.
What is not required in the activated sludge process?
3. What is required to keep the activated sludge suspended? Explanation: To maintain the aerobic conditions and to keep the activated sludge suspended, a continuous and well-timed supply of oxygen is required. Flocs of bacteria, which are suspended and mixed with wastewater is used for the process.
What is activated sludge How is it produced?
(a) As the BOD of sewage or waste water is reduced to about 10-15%, the effluent is passed into a settling tank where the bacterial flocs undergo sedimentation. The sediment is called activated sludge.
What is a good sludge age?
The common range for sludge age for a conventional activated sludge plant is between 3 and 15 days. For extended aeration activated sludge plants the range is between about 15 and 30 days. Generally during the winter months, higher sludge ages are required to maintain a sufficient biological mass.
What is the difference between sludge and activated sludge?
This sediment is called activated sludge. Primary sludge Activated sludge (iii) It does not require aeration Formation of activated sludge requires aeration (iv) A lot of decomposition occurs during the formation of primary sludge Very little decomposition occurs during the formation of activated sludge.
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.
What is activated sludge 12?
Activated sludge comprises a mixture of microbes and suspended particles. In the primary treatment, the bacterial culture is produced to break down organic to carbon dioxide, water as well as other inorganic ions. Many aspects of organic matter in the wastewater system act as a source of food for such microbes.
How is activated sludge used to clean sewage?
The activated sludge process is an integral process used to treat wastewater. Air or oxygen is blown into raw sewage. The process oxidizes organic matters in the wastewater, producing new cells, carbon dioxide, and water. The sludge particles can then be removed through the process of gravity settling.
What is return sludge?
The recycled sludge in a POTW that is pumped from a secondary clarifier sludge hopper to the aeration tank.
Is waste activated sludge?
The excess quantity (mg/L) of microorganisms that must be removed from the process to keep the biological system in balance.
What is activated sludge 7?
After the aerator tank, microbes and human waste settle down and form activated sludge. The activated sludge is about 97% water. The water is removed by sand drying beds or machines. Dried sludge is used as manure, returning organic matter and nutrients to the soil.
Why is aeration important for activated sludge?
Aeration is an activated sludge process, promoting microbial growth in the wastewater. The microbes then feed on organic material, forming flocks which easily settle out.
Why recirculation is done in activated sludge process?
So, one reason for sludge recirculation is to control biomass distribution. And RAS flow is critical to clarifier performance. There are a couple of methods that are implemented. And this diagram shows again a clarifier with wastewater flow plus the RAS flow coming in and the RAS flow and the effluent flow going out.
Where is activated sludge formed?
Atmospheric air or in rare cases pure oxygen is introduced to a mixture of primary treated or screened sewage (or industrial wastewater) combined with organisms to develop a biological floc (“Activated Sludge” AS).
How is sludge treated?
Many sludges are treated using a variety of digestion techniques, the purpose of which is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids. The most common treatment options include anaerobic digestion, aerobic digestion, and composting.
Why is it called activated sludge?
They aerated the waste-water continuously for about a month and were able to achieve a complete nitrification of the sample material. Believing that the sludge had been activated (in a similar manner to activated carbon) the process was named activated sludge.
Which bacteria play important role in activated sludge treatment?
Protozoa play a critical role in the treatment process by removing and digesting free swimming dispersed bacteria and other suspended particles. This improves the clarity of the wastewater effluent.
What is the sludge recovery process?
Currently, sludge incineration processes are increasingly focused on the recovery of energy from the sludge in the form of heat (steam) or electricity. Incineration of sludge is currently applied worldwide more and more in combination with energy recovery, mainly on a large scale.
Which is used to remove sludge?
Dewatering decreases sludge liquid volume as much as 90 percent. Digested sludge is put through large centrifuges that work in the same fashion as a washing machine spin cycle. The spinning centrifuge produces a force that separates the majority of the water from the sludge solid, creating a biosolid substance.
