Wastewater Management and Treatment Technologies with Recycling and Reuse Issues in India Leading to Zero Liquid Discharge (ZLD)

Abstract

AbstractWastewater treatment and its recycling issues are considered to be as one of the greatest challenges in today’s perspective leading to sustainable water management practices. Wastewater generated from industrial, municipal and communities is contaminated significantly our available water resources and, in some cases, make it toxic as well. It has been estimated that by 2025 India will face severe water scarcity when the water availability in India will drop below 1,000 m3 per capita unless adequate and sustainable water management practices are initiated on immediate effect. So, these wastewaters must be treated properly before they are discharged. Currently, a very small percentage of domestic and industrial wastewater is treated in India. All large cities in India together generate over 30 billion litres of sewage of which only 6.2 billion litres is treated. In Class-I cities only 26% of the wastewater is treated while in Class-II cities a mere 4% of the wastewater is treated. In case of Industry, around 60% of wastewater is remaining untreated. Recently the Central and State regulatory bodies has implemented stringent discharge norms for wastewater to protect the quality of Nation’s water. Based on the fact, suitable technology solution must be taken into consideration to treat the polluted and sometime toxic wastewater generated from industries and municipalities. At the same time wastewater recycling and reuse issues must be given priority to protect country’s freshwater resources. Further, online monitoring of effluent quality standards has also been implemented by Central Board for close monitoring of wastewater related issues which at the same time helps to protect our fresh water resources nationwide. The Indian wastewater Industry presently facing acute problems with respect to treatment with recycling and reuse issues across the country as the existing facilities do not function up to the mark as desired in revised regulatory norms. The main reasons for the above problems are (a) selection of incorrect and some time backdated technology, (b) faulty design of the system, (c) poor operation and maintenance and (d) lack of operator training for skills and knowledge development. As per estimation, the metros and the largest cities in India are collectively responsible for producing around 38 billion litters of waste water every day, which will eventually need to be recycled. Treated waste water could be the answer to the future of a secure water source in the country. They can be used for industries like Thermal plants, Coal sector, Mining and Mineral processing which often not required so high purity water and thereby help to meet the other industrial and agricultural needs of the nation. Long term challenges of depleting ground and surface water resources can be addressed if waste water recycling is effectively implemented across the country. In the present paper, wastewater management practices in industrial and municipal sector with treatment methodology and various technological aspects have discussed. Different Biological Treatment technology based on conventional, fixed and fluidized bed using media as a carrier of Biological population have been covered. Advance waste water treatment technology like membrane bioreactor; application of membrane-based separation technology during tertiary treatment for recycle and reuse issues have also been taken into consideration. Comparison of Performance efficiency, space availability and cost economic factor of different technologies during primary, secondary and tertiary/advance treatment have been highlighted. Finally, concept of zero liquid discharge leading to sustainable water management practices has also been incorporated with one or two case study examples.KeywordsWastewater treatmentWater scarcityRegulatory discharge limitsFresh water resourcesOnline monitoring of effluent quality standardsWastewater recyclingMembrane based separation technologyTertiary/Advance treatmentZero liquid dischargeSustainable water management