Role of Microorganisms and Plants in Biological Treatment of Industrial Wastewater
- Different pollutants are present in the waste water released from different industries. The discharge of untreated wastewater into natural ecosystems poses a serious threat to all life forms , making the treatment of pollutants present in industrial wastewater a necessity for affordable and efficient methods.
- In general, the conventional wastewater treatment system involves complex procedures and is economically impractical. By means of micro-organisms (bacteria , fungi, yeast, algae) and plants, biological treatment processes may be a relatively inexpensive and environmentally friendly way to remove various pollutants from different industrial waste water sources.
- The use of biological systems to treat industrial waste water pollutants depends to a large extent on the source and characteristics of the waste water.
- The pollutants / xenobiotics of industrial waste water can be broken down by microorganisms for their growth and/or energy requirements. Biological systems have the ability to remove pollutants through absorption , adsorption, and enzymatic degradation processes from waste water.
- In the treatment of industrial waste water , a large number of enzymes, such as peroxidases, oxidoreductases, laccases, cellulolytic enzymes, proteases and amylases from a variety of biological sources, play an important role.
- The existence of various bacterial populations allows the majority of industrial waste water pollutants to be degraded.
- The bacterial treatment of waste water involves the aerobic or anaerobic conversion of complex organic matter into harmless simple compounds.
- Bacteria are often used for the treatment of industrial waste water because they are easy to grow, grow quickly and are suitable for degradation and even complete pollutant mineralization.
- In general, bacteria obtain their energy from the organic carbonaceous matter (pollutants) of industrial waste water.
- Some bacteria use industrial waste water pollutants as their sole source of carbon and energy. In the treatment of different industrial waste water treatments, several bacteria have been reported.
- These bacteria play an important role in the degradation of phenols, the removal of heavy metals (reduction of chromium from the leather industry), the decolorization of dyes from the textile industry, the decolorization of waste from distilleries and the removal of pollutants from other industrial waste water, such as aliphatic and aromatic hydrocarbons, heavy metals, insecticides and other pollutants by biosorption or enzymatic degradation.
- The following are just a few examples of bacteria involved in the treatment of pollutants from different industrial waste water sources: Aeromonas hydrophila and Bacillus sp. Pseudomonas putida has potential application for heavy metal bioremediation, Sphingomonas chlorophenolica is capable of complete pentachlorophenol (PCP) mineralization, and Pseudomonas fluorescence has the ability to decolorize wastewater from the distillery.
- Fungi are organisms that are multicellular. They have lower sensitivity to temperature , pH, nutrient, and aeration variations.
- Fungi have the ability, through biosorption or enzymatic processes, to treat the toxic pollutants of industrial waste water released from different industries into harmless products.
- Several isoenzymes are secreted by fungi that play a major role in pollutant removal. White rot fungi are ubiquitous in nature, such as Phanerochaete chyrosporium and Trametes versicolor, and their adaptability to extreme conditions makes them widely used microorganisms in industrial wastewater treatment.
- They manufacture various enzymes that are involved in the degradation of various xenobiotic compounds, including laccases, manganese peroxidases and lignin peroxidases.
- In the process of biosorption, white rot fungi can also remove toxic metals and other pollutants.Their activity in the production and biosorption of enzymes makes them more efficient in removing pollutants from industrial waste water.
- For example, Trametes versicolor and Rhizopus oryzae have been involved in the treatment of paper and pulp waste water; Phanerochaete chyrosporium has been found to be effective in removing colour from textile waste water; Aspergillus fumigatus has been effective in decolorizing distillery waste water; Fusarium oxysporum, Cadosporium cladosporioides, Gliocladium roseum, and Trichoderma koningii has been involved in removal of heavy metals from industrial wastewater.
- Algae are a diverse group of photosynthetic organisms capable of treating industrial waste water pollutants primarily through bioaccumulation and biosorption.
- They can accumulate organic and inorganic toxic substances, heavy metals, nutrients, and pesticides from the waste water in their cells / bodies.
- Through absorption, algae can remove the excess nitrogen and phosphorus present in industrial waste water. Nitrogen and phosphorus, which are essential components for algae growth, are commonly present in waste water.
- For the treatment of various industrial waste water, a broad range of algal species including Chlamydomonas, Chlorella, Spirulina, Scenedesmus, Pediastrum, Cosmarium and Botryococcus have been used.
- These species are used for the treatment and removal of colour , odour, nitrogen , phosphorus, heavy metals, BOD , COD and other contaminants from various industrial waste water sources.
- Pollutant removal with the use of plants is known as phytoremediation. This strategy involves the use of plants that demonstrate a high level of survival in contaminated sites and the ability to absorb pollutants, resulting in the evacuation of pollutants.
- Heavy metals, petroleum hydrocarbons, pesticides, organic and inorganic contaminants and industrial by-products have been effectively removed from plants.
- Plant species with potential for phytoremediation should have particular properties. At levels that are toxic to ordinary plants, they accumulate, extract , transform, degrade or volatilize contaminants and also have the ability to repair different pollutants at the same time.
- With any of the following methods, such as phytoextraction, phytostabilization, phytovolatization, phytodegredation, rhizofiltration, the phytoremediation process can take place.
- By adsorption and accumulation, the pollutants enter the plant primarily through the roots. In the roots, stems, or leaves, these pollutants could be stored; transformed inside the plant into less harmful chemicals; or transformed into gases that are released as the plant transpires into the air.
- Several plant species, mainly aquatic plants, are known for their ability to phytoremediate various industrial waste water treatments, such as Acorus calamus, Typha latifolia, Typha domingensis, Cynodon dactylon and Phragmites communis.