The event ‘waste water management need of the hour’, held on 9 December 2020, was jointly organised by IFAT India and Water Digest. Anupama Madhok Sud, Director and Editor of Water Digest, moderated the session. Keynote address was delivered by Special Guest Rajiv Ranjan Mishra, Director General, the National Mission for Clean Ganga.

 

Eminent panelists consisted of policymakers, researchers, industry stalwarts such as: 

 

R S Tyagi, Former Member,  Delhi Jal Board; Hemant Kumar Panda, Director, Soil Conservation and Watershed Development, Odisha;  Anshuman, Associate Director, Water Resources Division, Delhi; Dr Ajit Vishnu Salvi, Executive Engineer, Municipal Corporation of Greater Mumbai;  Sarbana Roy, Senior Vice President, Electro Steel Casting; Dr Indra N Mitra, Director, Technical and Project Development, Cambi India.

 

Over half the wastewater generated in the form of sewage is discharged untreated into nearby water bodies in India, adding  to this is the untreated waste water from industries as well as the run-off from various sources of pollution, such as agricultural fields, roadways, etc.  

 

SDG 6 specifically targets on proportion of untreated waste water and substantially increases recycling globally. Today, a lot of technologies are available pertaining to waste water management. 

 

Key Note Address: 

Rajiv Ranjan Mishra, Director General, the National Mission for Clean Ganga

 

The waste water management challenge is very huge in India. The first and foremost need is giving priority to waste water management as a sector. It is not considered as crucial as drinking water. Disposal of waste is looked upon very casually in India, unlike getting safe and clean drinking water. There was a report by the Central Pollution Board in 2018 identifying 351 polluted stretches in the country with different levels (Priority I, II, III, IV and V). There are huge stretches of polluted rivers in the country, including Ganga, but still have some healthy flow of water. The rivers are not only polluted by sewage waste, but also by agriculture waste and so on. 

 

Municipal waste should be given priority which the government is now doing through AMRUT mission, Namami Gange Mission, Smart Cities Mission and Swachh Bharat Mission. Priority is being given to sanitation along with drinking water. There is National Green Tribunal, Central Monitoring Committee, which is helping in developing rejuvenation work for other rivers apart from Ganga river. 

 

Every state, city and town has a proposal to set up a new sewage treatment plant (STP), however no one mentions about what happened to old STPs. Sometimes we set up a 50 MLD STP but don’t even utilise 25 percent of its capacity. In waste water treatment management, apart from creating the capacity it is important to utilise it correctly. As a regulatory authority, the Clean Ganga Mission also looks into the old STPs and in case the capacity utilisation is less, it undertakes a study. 

 

Later on PPP was also introduced in this sector, and hybrid annuity mode (HAM) was brought where the Centre pays 40 percent during construction and operator brings investment, who will get back his 60 percent with interest. HAM was introduced to improve performance of project management. One City One Operator approach was also introduced where one operator was given responsibility of all STPs in the city. 

 

Slowly the revenue generation model is being introduced in which use or reuse of by-products of STPs becomes very important. STPs in Varanasi, Dinapur are taking their own load by generating internal power. Treated waste water use is being done in Mathura, Uttar Pradesh.

 

R S Tyagi, Former Member, Delhi Jal Board spoke about the impact of waste water management, current status of waste water treatment and septage management, the need of the hour, a case study of rejuvenation of water body and initiatives by the Delhi government.

 

The storm water drain is only meant for storm water but due to poor waste water management, waste water is also going into the storm water drains which flows through natural drains and ultimately pollutes surface water, and when it flows through natural drains the water percolates and pollutes ground water. This leads to water borne diseases. The emission of obnoxious gases from waste water also leads to air pollution. The waste water further contaminates soil when crops are irrigated with drain water. 

 

The current status of sewage generation and treatment in metropolitan cities is 51 percent, in Class-I cities 32 percent and Class-II cities only eight percent. Only 10 percent of sewage treatment plants are functioning well; 36 percent are working satisfactorily, 33 percent are poor and 21 percent are very poor.  

 

Currently Delhi is 55 percent sewered. The sludge from septic tanks is removed manually without using safety equipment, costing human lives. Sludge is removed by suction machines, honey suckers, but there is no proper mechanism for collection and transportation of septage/ septic tank waste. The private vendors are cleaning septic tanks and throwing the waste in water bodies and drains thus polluting them. 

 

Sewage is not waste but an asset as treated water reduces stress on filtered water supply demand to the extent of 70 percent and provides manure   and generates power from biogas. Isolation of sewerage system from storm water system is the need of the hour.

 

The main opportunities for reuse of treated waste water in and around the city are: irrigation and horticulture, use as cooling water in  power station, industrial use, construction industries, fire fighting, ground water recharge, water bodies, return to the raw water source and flushing toilets and washing.

 

Likewise the sludge can be used for manure as well as for fuel as it has got good calorific value approximate 3,000 kcal/kg. Dried sludge has up to 85 percent solid concentration and can be used as a fertlitizer, it is also pathogen-free.

 

There was a case study in Delhi on Rejuvenation of Rajokari Water Body. Prior to the revival of Rajokari water body in South-West district of Delhi, it was heavily polluted with sewage water with solid waste dumping and highly encroached. The storm water surface run-off was going to roads/colony, resulting in waterlogging. 

 

The Delhi government took initiative to rejuvenate this water body by removing all encroachments in the catchment area. The catchment area was demarcated and defined. All storm water drains were regraded and diverted towards water body so that rain water rushes into water body. The entire surface area was made compatible for catching every drop of water. 

 

A sewage treatment plant on wetland technology was set up at the mouth of the drain carrying sewage. The outcome of the project was that the water table has been increased by 1.4 mtr during previous monsoon. Sewage water from the surrounding is being treated by constructed wetland system and discharged into water body. Landscaping was done to uplift the beauty of the surrounding area. It is also used as a recreational space for the community nearby.

 

Some of the Delhi government initiatives include -- development charges in U/A-regularised colonies reduced to 20 percent i.e. from Rs 500 per sq mtr to Rs 100 per sq mtr; introduction of septage management regulation; free Chief Minister Septic Tank Cleaning Scheme in unsewered areas. A total of 255 water bodies have been taken up rejuvenation by Delhi Jal Board and Irrigation & Flood Control Department. 

 

Hemant Kumar Panda, Director, Soil Conservation and Watershed Development, Odisha

 

The main focus is on the state of Odisha; its agricultural waste water management in watersheds approach and treated waste water in agricultural use. Some of the causes of agricultural waste water are sediment runoff/soil erosion due to contour farming, crop mulching, riparian buffers, crop rotation, nutrient runoff, pesticides and animal wastes.

 

The government took up the gravity-fed, spring-based irrigation system at Putsil, Koraput in Odisha. The project is situated amidst the Deomali hill range, the highest mountain peak of Odisha, Eastern ghat at the elevation of 1,672 mtr from MSL. The springwater got wasted so the project was proposed to check soil erosion and provide irrigation to 47 acre of net sown area. Koraput district of Odisha has received the National Water Award from the Jal Shakti Ministry for 2017-18 for recharge of groundwater.

 

Dr Ajit Vishnu Salvi, Executive Engineer, Municipal Corporation of Greater Mumbai spoke about Mumbai waste water disposal project with recycle and reuse planning. Mumbai has a population of 12.44 million as per Census 2011, with a total area of 438 sq km. The water supply capacity of the city is 3,850 ml and sewage generated is 2,190 MLD, and more than 30 percent of Mumbai is unsewered. The sewerage system is divided into seven sewerage zones consisting of 1,987 km of sewer lines, 51 pumping stations, seven treatment facilities and three marine outfalls. The sewerage zones are Colaba (37 MLD capacity), Worli (757 MLD capacity), Bandra (797 MLD capacity), Versova (180 MLD capacity), Malad (280 MLD capacity), Ghatkopar, Bhandup (280 MLD capacity). 

 

Some of the challenges in implementation of new projects in Mumbai include inadequate land, removal of mangroves as per environmental rules on land proposed for STPs, clearances from Environment Ministry and Coastal Regulatory Zone authority, encroachment, selection of technology-most economical (low capex or opex).

 

Some of the challenges faced in the implementation of recycle and reuse policy are -- maintenance of tertiary treatment facilities, provision of distribution network, maintenance of distribution network, tariff for fresh water and recycled water, public awareness, restriction of reuse of recycled water, assurance of quality of recycled water.

 

The new projects will help in achieving some key aspects--conservation of environment, improvement of public health of Mumbai city, improvement in sea aquatic life, recycle and reuse of water, reduction in demand of fresh potable water.