What is the main goal of Secondary Wastewater treatment?
It has the ability to degrade biodegradable dissolved and suspended organic matter. It is also feasible to remove dissolved nitrogenous and phosphorous components from a wastewater stream via secondary treatment.
Biodegradable compounds are organic chemicals that degrade in the presence of bacteria (which are ubiquitous). Enzymes (complex proteinaceous compounds) are produced by microorganisms and function as catalysts in biodegradation processes.
These processes are carried out by a sequence of reactions known as biochemical pathways.
It's possible that the reactions will occur in the presence of dissolved oxygen. Aerobic responses are what they're called (processes). Some processes occur in the absence of oxygen entirely. Anaerobic/obligate anaerobic processes are what they're called. The reactions that occur under aerobic conditions differ from those that occur under anaerobic conditions. Since secondary wastewater treatment is all about these biological activities, thus, is also called as biological treatment!
The major goal of secondary wastewater treatment is to get rid of BOD, which does not gain as much from primary settling as SS does.
It is a biodegradation process that converts organic waste into non-polluting end products such as water, CO2, and biomass.
It can also be stated as:
The main goal of secondary treatment is to eliminate the majority of the fine suspended and dissolved degradable organic matter that remains after primary treatment, allowing the effluent to be discharged. In many situations, conventional secondary treatment may reduce BODs to less than 20 mg/l and Suspended Solids to less than 30 mg/l, which is acceptable.
The second goal
The decrease of ammonia toxicity and nitrification oxygen demand in the stream is the second goal of secondary treatment. During treatment, the majority of the ammonia is converted to nitrate (nitrification).
Nitrification is the process of converting ammonia into nitrate. Aerobic biological processes are capable of nitrification. If they are operating at low organic load rates, the units must be larger than those necessary for carbonaceous matter oxidation alone.Conventional sedimentation, the primary wastewater treatment process, typically eliminates 60 to 70% of suspended particles matter, which contains 30% to 40% of the BOD found in municipal wastewater, leaving 150 to 200 mg/l BOD and around 100 mg/l SS in the primary effluent.
Only if extremely high volumes of water are available for delectation or where the effluent may be irrigated across a vast land area, it is conceivable to discharge an effluent of this quality that exceeds the assimilative capacity of the receiving environment. A significantly better quality is required for discharge to inland streams or lakes.
O2 assimilation capability in H2O = 9mg/l with a minimum of 2mg/l.
Biological Wastewater Treatment Processes
1: Aerobic biological process;
2: Anaerobic biological process;
3: Facultative biological process;
Biological Treatment systems
1: Attached growth processes;
2: Suspended growth processes;
3: Dual (hybrid) biological treatment processes.
Secondary treatment of wastewater can be accomplished using chemical unit processes such as chemical oxidation, coagulation-flocculation and sedimentation, chemical precipitation, and so on, or biological processes (aerobic or anaerobic) in which bacteria act as a catalyst for pollutant removal. Biological treatment procedures are widely utilized across the world to remove organic materials from wastewater. As a result, for the treatment of wastewater such as sewage and many agro-based businesses and food processing industrial wastewaters, a biological reactor, either single stage or multi stage, will usually be used, depending on the requirements to fulfil discharge regulations.
What can we offer?
If you need help designing an efficient onsite wastewater treatment system or a water treatment system, contact Netsol Water. We can help you with design calculations, budgetary expenses, preliminary layouts, and a lifetime cost analysis.