Questions from Effect of Industrial Effluents on Soil and Water Pollution

Questions:

How are soil and water polluted by industrial effluents? What are the strategies to minimise this problem ?(20 Marks, IAS 2017 Agriculture Optional)

Answer.

Effect of industrial effluents on soil and water pollution. 

 

Effect on soil pollution

• Industry effluents increase CEC, EC, pH, Heavy metal accumulation which leads to alkalinity, salinity and acidity of the soil. 

• Effluents decrease the porosity and aeration, affecting the structure and infiltration. 

• Industry effluents also reduce the population of microorganisms and fauna of the soil. 

• Long-term application of wastewater may cause the following effect : 

1) Yield loss and decline in soil microbial activity. 

2) Soil and groundwater contamination. 

3) Reduction in soil fertility. 

4) Contamination of the human food chain. 

• Paper and pulp effluents contain lignin and phenolic compounds resistant to decomposition, have high BOD so direct disposal causes harmful effects to soil. 

• Sugar mill effluents contain higher amounts of suspended solids, dissolved solids, BOD, COD, chloride, Ca, Mg affects crop production, soil properties.

 

Effect on water pollution

• Industry such as food production, sugar factory, tannery, distillery, textile and dye, paper and pulp, brewery, petrochemicals, iron and steel manufacturing disposed-off water pollutants as natural organic compounds like tannin, resin, mineral oil and other livings ; gas and coke plants, painting yards and pesticide industries disposed-off synthetic organic compounds like Phenol, benzene, thinners, solvents, PCBs, polyethylene glycol.

• Surface water pollution by direct discharge of effluents- 

1) Heavy metal accumulation. 

2) Eutrophication. 

3) Reduce the productivity of the system. 

4) Biomagnification.

• Groundwater pollution by infiltration: 

1) Reduce the water quality by increasing salinity, alkalinity and heavy metal. 

2) Reduce the plant's productivity by affecting its metabolism. 

3) Not fit for drinking and irrigation. 

4) Major pollution fluoride, arsenic and nitrate.

Strategies to minimise the effect of industrial effluents 

• The industrial effluents must be monitored continuously to avoid the excessive accumulation of toxic metals in the soil.

• There should be strict Government law that only those industrial effluents be used in the fields which are cleaned through effluent treatment plants. 

• It is set out in the Environment Protection Act 1970, all wastes should be managed in the following order of Preference: Avoidance Reuse Recycling Recovery of Energy Treatment Disposal.

• Blending of water : Effluents from industries must be diluted to avoid their adverse effect on soil.

• Application of organic manures boost the yield of soil as well as decrease the metal availability to plants.

• Bioremediation is the use of biological agents such as bacteria, fungi and plants to remove or degrade the pollutants from the contaminated soil. 

• Phytoremediation is planting of  tree species like Azadirachta indica and Acacia nilotica etc. The toxic compounds are trapped into the trunks of such trees which will remain for a longer time and will not come to the food chain as well.

• Vetiver grass could grow well on soils contaminated with high concentrations of Pb and Cd. It reduced the concentration of Pb by 38 - 60% and Cd by 35 - 42% in soil. 

• Heavy phosphate and zeolite application to soils can reduce the availability of heavy metals; Zeolite reduced the Pb content of rice grain by 69% and Cd by 67%.