Sludge treatment is a very important job in any wastewater system. Sludge is always generated during wastewater treatment. Effective principles and handling will help the system always achieve optimal efficiency
Definition of mud
Sludge is a by-product of wastewater treatment in any conventional wastewater treatment plant. And while treated water can be discharged to receiving sources as required by discharge permits, sludge treatment is much more complicated.
One of the tasks of the wastewater treatment process is to convert pollutants, from dissolved to solid form, and to separate solids from the liquid phase. Solids after dehydration (concentration) are collectively known as sludge, contain many different components and must be disposed of properly. Among the components to be treated, sludge occupies the largest volume, and sludge treatment and disposal techniques are one of the most complex issues. Sludge treatment equipment accounts for 40-60% of total wastewater treatment system construction costs and treatment costs account for about 50% of total system operating costs.
Sludge from water and wastewater treatment plants is a mixture of water and sediment containing many degradable, easily rotten organic substances and bacteria that can be harmful to the environment, because Therefore, it is necessary to have treatment measures before discharging into receiving sources.
Origin of sludge generation
Waste sludge is formed after biological treatment, including activated sludge after Aerotank tank or biofilm sludge after biological filter tank, collectively known as secondary sludge. A large part of this sludge is returned to the Aerotank tank (called circulating activated sludge), the rest of the sludge called residual activated sludge is led to the sludge compaction tank.
The total suspended solids content of TSS in wastewater is usually 50-70g/person/day.night. About 25-50 grams of sediment/person/day/night are retained in the first stage of treatment. The moisture content of the residues after 2h settling is 97.5%, then they are gradually compressed in the concentration pit to 92-95% humidity. The average volume of this sediment is 0.6-0.8 liters/person/day.night. Because this is an insoluble component in wastewater, it is called primary sediment. In this residue, 65-70% are organic components, many microorganisms including pathogenic microorganisms.
Properties of sewage sludge
The sludge from the first settling tank is called fresh sludge because the organic compounds in the sludge have not been decomposed, and the sludge from the second settling tank is activated sludge with a floc form, because it has been biologically treated. organic matter present in the residue has been partially decomposed.
Sludge generated from domestic wastewater treatment system contains many organic substances, contains many bacteria including pathogenic bacteria, high humidity, using fresh sludge as fertilizer is not beneficial and difficult to transport.
Accordingly, sludge generated from industrial wastewater treatment processes contains high levels of heavy metals such as Cu, Cr, As, Ni, Cd, etc., especially sludge generated from the treatment system. concentrated wastewater of the industries of manufacturing, preparing inorganic and organic chemicals, treatment, surface covering, metal processing and other materials.
Moreover, production activities in industrial parks and export processing zones are mostly multi-industry, so the sludge generated from the centralized wastewater treatment system has a complex composition, containing many hazardous components. The number and hazardous components fluctuate, making it difficult to control, the volume generated is large, so the amount of sludge from the above mentioned industrial zones poses the risk of environmental pollution if no appropriate control measures are taken. . Sludge from industrial wastewater treatment system
Waste sludge classification
Biological waste sludge
This sludge has a very unpleasant odor but is non-toxic and can be used to produce organic fertilizer by adding lime powder to reduce acidity and using EM to deodorize and convert it to organic fertilizer. synthetic.
Industrial sludge is hazardous
This residual sludge contains heavy metals such as: Cu, Ni, Hg, Mn, As, .. and needs to be treated immediately before being discharged into the natural environment, so as not to affect and cause harm to the environment. nature as well as future generations.
Industrial sludge is not harmful
This type of sludge does not need to be treated and can be utilized for many different purposes when the wastewater treatment process is complete.
The current status of sludge generated from the wastewater treatment system of industrial plants is being treated by modern mechanical machines such as plate-frame mud presses, conveyor mud presses, screw mud presses, etc. suitable for each type of sludge.
For details, please refer to the slurry press that KS Boiler is providing for many businesses that are effectively treating sludge at: Multi-disc screw mud press