What is secondary treatment of wastewater in a treatment plant?
Secondary treatment is a treatment process for wastewater (or sewage) to achieve a certain degree of effluent quality by using a sewage treatment plant with physical phase separation to remove settleable solids and a biological process to remove dissolved and suspended organic compounds.
What are the different methods of secondary treatment of sewage?
Secondary biological processes can be aerobic or anaerobic, each process utilizing a different type of bacterial community. Coupled anaerobic–aerobic processes may also be employed under certain circumstances. Aerobic – Aerobic biological processes are common in municipal wastewater treatment.
What is activated sludge treatment process?
The activated sludge process is a type of wastewater treatment process for treating sewage or industrial wastewaters using aeration and a biological floc composed of bacteria and protozoa.
How can you improve settling in activated sludge?
Excess organic load can be remedied by reducing the waste-activated sludge rate by an amount less than 10 percent per day, to return to proper loading parameters and increase the returned activated sludge rates. About a 30 percent level of settled solids in the clarifier should be established and maintained….
What is the difference between primary and secondary sludge?
It is sludge formed during primary sewage treatment. It is sludge formed during secondary sewage treatment. A lot of decomposition occurs during the formation of primary sludge. Very little decomposition occurs during the formation of activated sludge.
What is the difference between primary and secondary water treatment?
The basic function of wastewater treatment is to speed up the natural processes by which water is purified. In the primary stage, solids are allowed to settle and removed from wastewater. The secondary stage uses biological processes to further purify wastewater. Sometimes, these stages are combined into one operation.
What is tertiary treated water?
Tertiary treatment is the third, and final, stage in a standard wastewater management system. Once effluent has been treated in the primary and secondary stages by removing suspended solids, pH balancing and reducing its biochemical oxygen demand (BOD), it is ready to enter the tertiary stage.
What materials Cannot be removed from wastewater?
When wastewater arrives at the treatment plant, it contains many solids that cannot be removed by the wastewater treatment process. This can include rags, paper, wood, food particles, egg shells, plastic, and even toys and money.
Do water treatment plants remove pharmaceuticals?
It might sound surprising that these drugs could be detected in streams miles downstream from wastewater-treatment plants, but many plants do not routinely remove pharmaceuticals from water….
What is a main goal of primary treatment in a modern sewage treatment plant?
The objective of primary treatment is the removal of settleable organic and inorganic solids by sedimentation, and the removal of materials that will float (scum) by skimming.
How are chemicals removed from wastewater?
Chemical precipitation is the most common method for removing dissolved metals from wastewater solution containing toxic metals. A chemical reaction, triggered by the reagent, causes the dissolved metals to form solid particles. Filtration can then be used to remove the particles from the mixture.
What chemicals are used to treat sewage?
Certain basic or alkaline chemicals used to raise wastewater pH are below: CaO (calcium oxide or lime), MgO (magnesium oxide), Ca (OH) (calcium hydroxide, a hydrated form of lime) or Mg (OH) (magnesium hydroxide) are the most commonly used chemicals because of availability, low cost, and high capacity….
How can we reduce BOD and COD in industrial wastewater?
BOD and COD Removal Hydrogen Peroxide (H2O2) Hydrogen peroxide (H2O2) has been used to reduce the BOD and COD of industrial wastewaters for many years.
What causes COD in wastewater?
Chemical oxygen demand (COD) is often used to measure organic matter in wastewater, treated effluent, and receiving waters. Residual food waste from bottles and cans, antifreeze, emulsified oils are all high in COD and are common sources of COD for industrial stormwater….
What is BOD and COD in water treatment?
Indian Institute of Science. COD or Chemical Oxygen Demand is the total measurement of all chemicals (organics & in-organics) in the water / waste water; BOD is a measure of, the amount of oxygen that require for the bacteria to degrade the organic components present in water / waste water.
What is BOD COD and do?
BOD is the amount of oxygen that will be consumed by bacteria or other aerobic microorganisms while decomposing organic matter under aerobic conditions. COD measures the amount of oxygen that will be consumed by the chemical breakdown, or oxidation (degeneration) of organic pollutants in water….
What is BOD COD ratio?
BOD (Biochemical oxygen demand) is the pollution index of any water sample. BOD : COD (Chemical oxygen demand) ratio using the formulated seed comes in the range of 0.7-0.8 whereas that using BODSEED comes in the ratio of 0.5-0.6. The ultimate BOD (UBOD) was also performed by exceeding the 3-day dilution BOD test.
What is a good COD level?
BMS have recorded average ratios of 2-3 mg/l COD to 1 mg/l BOD over its 30 years of business. Influent COD in normal domestic sewage is therefore generally 600 – 900 mg/l and it is then treated to at least 75 -100 mg/l before discharge to minimise pollution potential….
How is COD BOD ratio calculated?
To establish the COD:BOD ratio for your wastewater, simply have both COD and BOD run on several wastewater samples. Divide the COD concentration by the BOD concentration for each sample and average the results.
How is bod calculated?
#2 Seed BOD = (DO depletion x 300)/Seed dilution, mL The calculated seed BOD represents the BOD exerted by 300 mL of undiluted seed material. The ratio of the seed BOD to 300 mL will be used to calculate the seed correction for seeded samples.