Top Trends In Biological Processes Of Treating Wastewater

Biological wastewater treatment systems operating today have undergone a major evolution over the last century. Modern sewage works employ state of the art computerized and engineering electronics. Operating such modern plants is backed up by research into the physiology of organisms that are involved in the treatment of wastewater and much-sophisticated work is going to improve the treatment of high volumes of sewage effluent produced by various industries. Let us look at some examples of recent developments in biological wastewater treatment.

Enhanced biological removal of phosphate

Development of enhanced biological removal of phosphate is achieved in an anaerobic-aerobic wastewater treatment system. This process is characterized by a zone of anaerobic process at the influent end of the treatment system and the aerobic zone of the activated sludge system. In a treatment plant, the anaerobic part of the system imposes a very strong selective pressure that favours organisms that can take up organic substrate in anaerobic conditions.

PAOs or phosphate accumulating organisms are favoured because they have stored energy reserves such as polyphosphate which enables them to take up substrate in anaerobic conditions. The polyphosphate accumulating organisms take up phosphate from the solution and add it into their biomass. This can then be eliminated and thereby get rid of the phosphate from the wastewater being treated. Some organisms in the effluent grow anaerobically without polyphosphate and these are known as glycogen accumulating organisms.

Competition between glycogen accumulating organisms and polyphosphate accumulating organisms is very important because the proliferation of the polyphosphate accumulating organisms to good phosphate removal while when the glycogen accumulating organisms dominate, the removal of phosphate is reduced in biological wastewater treatment systems. The organisms involved in this process are something of a mystery. Back then people used to think it was a species of the bacterium acinetobacter but it is not the case.

Recent advances in nitrogen removal

Anaerobic and aerobic processes are regarded as being spatially separated naturally and in wastewater treatment systems, processes associated with anaerobic and aerobic conditions were thought to be separate. We assume you already know that denitrification and nitrification can take place simultaneously in microbial co-cultures, communities and even single pure culture. Some species of Nitrosomonas associated with nitrate oxidation can also anaerobically denitrify nitrite to nitrate and nitrite oxide. A lot of organisms are capable of heterotrophic nitrification and can also denitrify. Anaerobic ammonium oxidation has been seen to occur in which the oxidation of ammonium to nitrate serving happens as an electron acceptor under anaerobic conditions.

Microbial decolourization of water that has been polluted by dye

Dyes can pollute river water and when that happens, it is normally removed by activated charcoal. Biological wastewater treatment methods using fungi show a great improvement. Despite this, dyed water presents a great problem for biological treatment processes since it has a wide range of pH and high salt concentration. It is also rich in chloride ion. Dye colour removal can be achieved by microbial means. A wide range of microorganisms can remove dyes from water.

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