Thermax helps the City of Udaipur rejuvenate lakes and contribute to conserving environment. Water has become a critical resource. Rapid increase in demand and contamination of natural water resources are responsible for shifting the country to water stressed zone. 70% of the total water consumption is drawn by Agriculture. Household and Industrial demands account for 10% & 20% respectively. Thus, recycle and reuse of the sewages coming from these sources are the most viable alternatives to reuse water. In India, only 35% of the total domestic water is treated. Industries could utilize this sewage as a source of raw water whichotherwise flow through the rivers. Recently, it has been observed that decentralized treatment systems are more successful than common effluent treatment facilities for industrial sewage treatments.

The city of lakes, Udaipur under the Smart City programme along with Hindustan Zinc Limited (HZL) has taken it upon themselves to treat and recycle the domestic sewage of the entire city and use it for industrial consumption (end-use application). ThermaxWater and waste water solution division after successful execution of 20MLD STP plant hassupplied 25 MLD plant which is being commissioned presently. The sewagefrom the city is treated using MBBR (Moving Bed Bioreactor) technology. Anoxic and aerobic unit processesworking on the attached growth principle were used for the treatment.

Anoxic treatment is used for the reduction of nutrients like nitrogen from the sewage. Organic matter will get reduced in aerobic MBBR (Moving Bed Bioreactor)and bio-solids are removed in advanced sedimentation treatment unit called klaritubesettler.MBBR and Klaritubesettler offered an advantage of lower operating cost and space requirement compared to other conventional available treatment schemes.Clarified sewage is further polished using rapid gravity sand filters ensuring the treated sewage quality as per latest disposal norms after the disinfection. The treated sewageis used by the client for end use applications.

A sludge handling system is also provided to reduce the water loss. The plant is designed for least manual interventions by providing mechanical motorized equipments. Thus the use of domestic sewage for industrial activities could reduce the withdrawal of water from natural water bodies. Significant volumes could be utilized for reuse such as make-up water and other process consumption. The plant is designed to treat 25000 m3/day of sewage, to deliver a BOD of ≤10 mg/l, with COD and TSS of ≤30 mg/l and ≤5 mg/l. The total nitrogen content is designed to meet 10 mg/l. Thus, use of technology in different approach for water management took HZL a step ahead for sustainability. With this sewage recycle we contribute to saving more than 90% of demand of the fresh water for sustainability use for industry.

Thermax Water and Waste Solutions offer “One-Stop Solution” to support industrial and commercial sectors to treat water, sewage and effluent sewage for their end applications to meet stringent pollution norms. Thermax also offers solutions in Sewage Recycle, Zero Liquid Discharge and Desalination, in addition to Comprehensive Solutions in Plant Management, Plant Upgrade & Improvement, Specialized Audits and Spare Parts Management, and Specialty Chemicals.

Authored By:

Nandan Prabhune,
Technology and Innovation Group,Water and Waste Solutions,Thermax Limited

Renuka Devmane,
Industrial Projects Group,Water and Waste Solutions,Thermax Limited