Posts in Biological Wastewater Treatment

Why is biological wastewater treatment used?

November 7th, 2016 Posted by Biological Wastewater Treatment 0 thoughts on “Why is biological wastewater treatment used?”

Microorganisms and bacteria are microscopic, free-Living organisms that can reproduce at an enormous rate of if the proper environmental conditions are met. Microorganisms are the primary agents of biological wastewater treatment. Biological wastewater treatment is the use of bacteria to degrade and decompose organic materials during treatment.


  • Traditional WWTP’s have used the bacteria and microorganisms that exist naturally in sewage effluent to use as base for treatment of effluent.
  • SewTreat has developed a highly effective multiple strain bacteria range that gets added to our plants. This specifically bred bacteria feed on the complex substances in the wastewater, converting them into simpler substances, improving treatment.

Due to their growth, adaptability, and resilience, wastewater treatment systems rely on microorganisms to degrade organic material and produce clear effluent water. By harnessing the ability of microorganisms to tackle the source of larger issues – degrading odour – causing compounds, for example – biological wastewater treatment offers major advantages over alternative treatment strategies.


These advantages include:

  • Lower operating costs compared to alternatives
  • Efficient degradation and removal of organic and inorganic compounds
  • Improved flexibility to handle a wide range of wastewater characteristics and flows


The key, however, to any biological treatment system is ensuring that the existing microbial community has the right conditions to grow.

The Effect of Biological Wastewater Treatment on the Environment

November 3rd, 2016 Posted by Biological Wastewater Treatment 0 thoughts on “The Effect of Biological Wastewater Treatment on the Environment”

Globally, the composition of effluents discharged to receiving waters is regulated by the national environment agencies. The legislation is concerned with the prevention of pollution and therefore sets concentration limits on dissolved organic carbon (as BOD or COD), nitrogen and phosphates which cause eutrophication in receiving waters. This legislation also attempts to limit the discharge of known toxic chemicals by setting allowable concentration limits on the effluent.

If we consider that 100% of the effluent can be recycled, if done properly, there is no doubt that through this we are providing large bank of water which previously may not have been considered as ‘safe’ for the environment or community.

In fact, innovative wastewater management can result in the redistribution of this water into the environment for irrigation, flushing of toilets and dust suppression, as well as to replenish rivers and catchments in our water infrastructure networks. The technology is so advanced today, that effluent can even be treated further to potable (drinking) water for areas where it is in short supply.

These types of water recycling programs not only have a highly positive impact on the availability of water but make it possible to enable previously non-consumable water to be used in key areas within community resulting in quality water for consumption and use in gardens, industry, etc.

SA Standards of Final Effluent Quality:

what is biological wastewater treatment

What is biological wastewater treatment?

October 20th, 2016 Posted by Biological Wastewater Treatment 0 thoughts on “What is biological wastewater treatment?”

Biological wastewater treatment is an accepted practice that is used worldwide. This process involves confining naturally occurring bacteria in tanks at a very high concentration. From here this bacteria, together with some protozoa and other microbes (collectively referred to as activated sludge) are treated in an anaerobic and an aerobic process. They are then returned to the anaerobic phase to eliminate sludge production and waste.


In a nutshell, the bacteria remove small organic carbon molecules by ‘eating’ them. This result is growth of the bacteria that digest all impurities and the wastewater is then cleansed. The treated wastewater or ‘effluent’ can then be discharged to receiving waters – normally a river or the sea, or alternatively used for irrigation, flushing of toilets or general non-potable uses.
The main processes used in a Biological Sewage treatment plant can be summarised as follows:

what is biological wastewater treatment

Phase 1: Intake works, using of screens, clarifiers and in some cases FOG removal

All inorganic and undesirable matter is removed.


Phase 2: Anaerobic treatment processes

The anaerobic treatment processes take place in the absence of air by those micro-organisms (also called anaerobes) which do not require air (molecular/free oxygen) to assimilate organic impurities. The final products of organic assimilation in anaerobic treatment are methane, carbon dioxide gas and biomass.


Phase 3: Aerobic treatment processes

As the title suggests, aerobic treatment processes take place in the presence of air and utilise those microorganisms (also called aerobes), which use molecular/free oxygen to assimilate organic impurities i.e. convert them in to carbon dioxide, water and biomass.


Phase 4: Clarification and anoxic treatment

Biomass that accumulates is recycled to the anaerobic zone where sludge reduction occurs, this is called re-activated sludge treatment.


Phase 5: Disinfection

Final water is disinfected using ozone or chlorine from where the water is discharged as treated water.