Sunday , 24 March 2019

Welcoming Goa’s Modern Solid Waste Treatment Plant

Nandkumar Kamat
The irresponsible behaviour of producers of solid waste in Goa resulting into un-segregated solid waste is the real bane for any solid waste treatment or disposal project. On May 30, Goa’s 30th Statehood Day on the Calangute-Saligao plateau a modern, state of the art solid waste treatment plant (SWTP) built with imported technology, foreign technical knowhow costing about Rs. 150 crores to be operated by just two years old company Hindustan Waste Treatment Pvt Ltd for a period of 10 years would be formally commissioned. This is a private company incorporated on June 27, 2014 having SP Dhandoria, SK Garg, SD Desai, SP Gandhi as directors.
Treatment of one metric ton of solid waste at this plant may cost Rs. 1500-1600 for the government. Goa generates more than 100 thousand MT of solid waste annually and its treatment would need an annual budget of Rs. 16 crores. The Calangute plant capacity has been capped at 100 MT per day or about 40 thousand MT per year meeting only 40 per cent of the state’s needs.
At Calangute SWTP, trucks would transport mixed waste and dump it at the 500 MT capacity tipping floor right at the entrance. A conveyor belt would then segregate the waste with manual monitoring by trained workers into nine items like metal, plastic, glass, paper etc. The incinerable fraction larger than 80 mm would be packed as Refuse Derived fuel (RDF). Smaller fraction would be subjected to OREX technology. Organic waste would be converted as fertilizer and sold. The leachate from SWTP plant with high BOD would be used for biomethanation. There is an effluent treatment plant (ETP) for treatment of on-site wastewater based on the sequential batch reactor (SBR) technology. As a member of the official delegation of Goa State Planning Board (GSPB), I had opportunity to inspect the SWTP on May 18. My inspection was not satisfactory, especially about selection of the site as the location is on a ridge, an ecosensitive watershed of Salmona spring and Nerul river, a highly windswept area, attracting both predator and prey birds. The plateau with SWTP is at an altitude of 72 to 78 metres from sea level, lying just 700 meters from Nerul or Verem River, one kilometre from densely settled Gauravado, Calangute, two kilometres from Marra, Pilerne and Candolim and just 400 metres from Saligao’s Salmona Spring.
The 12 hectares campus of SWTP is not bird-proof. The bird menace would trouble the facility. The location despite guarantee of indoor precautions would cause spread of microbiological aerosol particles which would escape with fugitive emissions from the main processing unit. This aerosol swiftly dispersed by the wind would cause spread of new bacterial and viral pathogens increasing respiratory diseases from July to December in surrounding villages.
There are genuine concerns about formation of leachate which would take some time before it seeps into the deep aquifer and contaminates the surrounding water-bodies. Though we were assured that rainwater harvesting would be done to actually recharge the aquifer. But there is no on-site leachate monitoring and testing well neither an onsite chemical, microbiological analytical laboratory.
Growing fly and mosquito menace during monsoon is another concern. Insect control would be required at the site otherwise it would be a source of nuisance for Saligao, Pilerne, Calangute villages. Even during summer the odour from rotting waste was found unbearable inside the facility. It would get worse during the monsoon. Odour control would be also difficult unless malodor suppressing agents and sprays are used.
The real test of the plant would be daily treatment of 100 MT of mixed fermenting solid waste during windy, stormy monsoon. During summer things appear very bright and orderly. The location is swept by corrosive winds flowing from Arabian Sea. Such salt laden winds corrode all metallic structures. The entire SWTP machinery is made of iron, steel, aluminium, brass, copper, alloys and composites and maintenance of such complex moving machinery during monsoon would be a big challenge to the operator.
It is surprising that the massive plant failed to utilize favourable conditions to generate solar and wind power. But government has taken a huge risk by permitting generation of power by biomethanation because methane is a highly flammable, an explosive and toxic gas. The operators have no experience to handle biomethanation facility. The SWTP expects to generate 500-1000 KW of electric power. People in surrounding villages still don’t know much about biomethanation plant risk analysis report, on and off site disaster management plans although the site engineers assured us that there is a strong, insulated, double layered containment dome. If the biomethanation plant succeeds then it would be a model for whole country.
The success of Calangute SWTP doesn’t depend on technology but proactive, informed and responsible citizens, the real solid waste producers, who should be educated about segregation of solid waste at source. The Calangute SWTP machinery is truly world class but it would be successful only if village panchayats send well segregated waste for processing and GSIDC takes fail safe ecological, environmental and safety measures based on my comments above. This plant is a great educational facility for science teachers and students.

Please like & share: