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Overview Of Cassava Wastewater Purification System

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Environmental awareness and concern about pollution has been intensified for so many years now. Any substance present either in excess or less amount in the environment at the wrong time can cause pollution.

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Cassava processing is generally considered to contribute expressively to environmental pollution and to diminution of water resource quality due to the strong and unpleasant odour. Different types of wastes are generated in large amount in cassava processing industries depending on method and type of technology used in cassava processing. Large-scale processing of cassava, if left unchecked, will have great or huge impact on the environment. Cassava wastewater comprises complex components such as organic materials and nitrogen-containing compounds with a large amount of suspended solid and colloidal particles which are detrimental to human health. They can also cause aesthetic nuisance in the environment. Due to the above reasons, there is a need for effective treatment of wastes generated by cassava processing before being discharged into the environment.

Recently, the method of using bioflocculant and amylase to treat cassava wastewater has become a new research direction. This is because bioflocculants produced by microbes have the potential for easy treatment of secondary pollution and unique effects on the biodegradation of pollutants.

The application of the flocculants has been employed in various industrial processes including treatment of starch wastewater, drinking water purification and dyeing wastewater treatment. Flocculants are classified into three major groups: (a) organic flocculants (polyacrylic acid and polyacrylamide derivatives), (b) inorganic flocculants (aluminium sulphate and polyaluminum chloride) and (c) bioflocculants such as flocculants produced by haloakalophilic Bacillus sp. I-471, Alcaligenes cupidus KT201, Bacillus subtilis IFO3335, Nocardia amarae YK-1, Bacillus licheniformis and Rhodococcus erythropolis.

The first two groups are widely used industrially due to their low cost and efficiency. However, report have shown that they are disadvantageous to human health and are not environmentally friendly. For instance, acrylamide monomers of polyacrylamide were found to be both neurotoxic and carcinogenic to humans. It has also been reported that aluminium, the main constituent of polyaluminum may lead to the development of Alzheimer’s disease. Additionally, the reaction of alum with natural alkalinity nature of water results in pH reduction, therefore leading to low efficiency in the coagulation process.

Besides being toxic and non-degradable, an important economic factor with using chemical flocculants is that many developing countries cannot afford the high costs of imported chemicals for municipal water and wastewater treatment. Consequently, they depend on inorganic and organic synthetic flocculants, which are toxic and non-degradable. However, scientists have focused on finding an alternative and safer substitute to these chemical flocculants by screening of microorganisms that produce high yields of bioflocculants with strong flocculating activity. In addition, by optimizing the culture growth conditions as well as factors affecting flocculating activity, the flocculants-producing capability of the microorganisms are improved. The introduction and implementation of stringent standards for waste discharge into the environment has necessitated the need for the development of alternative waste treatment processes. A large number of enzymes from various microbes have also been reported to play crucial role in wastewater treatment applications.

Enzymes can specifically act on and remove recalcitrant pollutants by precipitation and transformation to other products. They can also change the characteristics of a waste, making it more susceptible to treatment or convert it into value added products. The use of enzymes in place of chemical is extremely important in order to meet the demands for cleaner and greener technologies that can aid the planet preservation.

The potential advantages of enzymatic treatment as compared to conventional (chemical) treatment include: application to bio-refractory compounds; operation at high and low contaminant concentrations; operation over a wide range of pH, temperature and salinity; absence of shock loading effects; absence of delays associated with the acclimatization of biomass; reduction in sludge volume and the ease and simplicity of controlling the process.

They can as well selectively degrade a target pollutant without affecting the other components in the effluent. In this respect, enzymes outperform the regular catalysts (transition elements like Cu, Ni etc. ) thereby making enzymatic wastewater treatment an ecologically sustainable technique.

18 May 2020

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