Water is a vital resource for the sustenance of human life and activities. Rapid urbanisation, climate changes and growing needs have put an ever increasing pressure on freshwater resources. The Industries also generate large amount of waste water as a consequence of the processes employed. Burgeoning cities have created greater demand for supply of water and also generated a large amount of waste water which if discharged without any form of treatment into water bodies may harm the aquatic life and the environment. Hence waste water management has become the need of the hour and water recycling has become imperative for their sustenance and growth.
Bearing all the threats and problems, United Nations (UN) has proposed to celebrate World Water Day on March 22 each year. The main objective of World Water Day is to save water resources and to solve the problems of clean water shortage in the world. The theme for this year is ‘Wastewater’ with larger emphasis on treating the contaminated water to save water resources for us and our future generations.
Waste water management is not only a science but also an art. Numerous technologies are available for waste water treatment and choosing the appropriate technology is a very important aspect of waste water management. There has been a constant endeavour amongst the ‘water professionals’ to innovate new technologies with the basic aim of reducing the reaction time, plant foot prints and cost of treatment.
The major innovations in the waste water management are:
De-centralised treatment plants: These are treatment plants specific to small communities/condominiums/buildings and are not connected to the main waste water treatment system. Such designs permit the community to utilise the waste water by recycling and help in conservation.
Satellite water reclamation plants: They remove flow from nearby sewers to produce reclaimed water close to the use area and thus avoid in laying of pipelines and pumping systems to return the reclaimed water to the use areas from central treatment plants.
Membrane separation technologies: It involves the separation of liquids from solids using Ultrafiltration, Microfiltration or Reverse osmosis (RO) technologies. The water produced is so clean that it is potable, though most of the applications of reclaimed water are for grey water and irrigation use.
Biodiesel from fats, oil and grease in waste water: Fats, oil and greases are collected from waste water and converted to biodiesel through esterification and hydrogenation.
Electricity and heat from co-generation: Biogas fuelled co-generation systems allow waste water facilities to utilise energy from treatment process itself. Co-generation produces electricity and hot water from biogas, a naturally occurring by-product of sludge dewatering. The electricity produced can be used to supply power to anaerobic digesters in the plant thereby offsetting electricity purchases.
Water source heat pumps: Water-source heat pumps are being used to extract residual heat energy from wastewater, after treatment and before discharge by outfall. Similar heat extraction technology is now developing for extracting heat from wastewater in sewer pipelines.
Apart from above innovations, waste water management also includes processes and strategies for their reuse so as to reduce the dependency for fresh water supplies. The technologies employed include Ultra filtration, Reverse Osmosis and Evaporation. Further considerable work is being done around the world to develop more effective materials used in the technologies with the aim of reducing costs and improve treated water parameters thereby improving the efficiency of the existing technologies by adopting different configurations.
In conclusion, technologies associated with waste water management are constantly evolving and has become the main focus of a large number of scientists, technologists and water professionals around the world. Waste water management is thus being viewed as an essential activity in environmental protection and water conservation.
By Dr. Abhay Kumar, Chief Scientific Officer, Eureka Forbes Institute of Environment