Clearing, sorting and turning in compost

SEDAWATTE -Colombo city produces approximately 1000 tons of garbage a day which was allowed to pile up at the dumping grounds in Bloemendhal for the past 20 years. Burns Environmental and Technologies Limited (BETL) came into the picture in 2002 under a 5-year contract with the Colombo Municipal Council (CMC) for solid waste management within the CMC limits.

Since the Bloemendhal dump and the garbage problem literally reached dizzying heights, Burns was brought in to dispose waste in an environmentally friendly manner.

BETL operates a composting plant in Sedawatta where garbage from the CMC and seven other local authorities – Maharagama, Gampaha, Kadawatha, Kotte, Mahara, Biyagama and Kolonnawa - are brought for processing.

The process begins when fresh garbage is brought into the Sedawatta compound. According to Sumith Jayawardena, General Manager of BETL, nearly 500 tons of garbage is processed each day at Sedawatta. “It is the largest such plant in South Asia,” Jayawardena said. The garbage that is brought in is manually sorted to get rid of as much plastic and polythene as possible. This plastic matter is then washed once and ground into pellets which are used for manufacturing items such as coat hangers and flower pots.

After the larger pieces of plastic that can be removed are taken out, the garbage is then allowed to decompose for 60 days, Jayawardena explained. Each pile is turned once a week during those 60 days, to ensure optimal microbial activity with only water and air added. The technicians ensure the proper temperature of 60 degrees Celsius is maintained.

To maintain the temperature and also to prevent emission of odours from the decomposing garbage, the piles are covered with a layer of saw dust.

After 60 days, the organic matter in the piles decompose and turn into a black matter with polythene and plastic matter that could not be extracted while still in the mixture.

The mixture is then sent through machines known as “trammel”. It is sent along a conveyor belt where more manual sorting takes place. Glass and large pieces of plastic are removed from the mixture and it goes into the section of the machine where the mixture is ground and sieved. It is finally separated and the compost is separated from the polythene matter. “68% of the garbage we get is unsuitable for turning into compost. Out of that, 52% is polythene,” the general manager said.

The compost, which is of two varieties – nutrient enriched and not enriched – is packed and ready for production. The plastic remains from the mixture is sent back to the Bloemendhal dump as there is not much that can be done with it. Jayawardena tells us that cleaning of plastic matter that goes through the decomposition is very costly and the other alternative is to use it in landfills. “The government is being very slow to grant the necessary permission for us to go ahead with this,” Jayawardena said, explaining that BETL has four plots of land which they can fill using polythene discards. As there is no other alternative at the moment, it is being sent back to the dump.

Jayawardena said that if the garbage is sorted at the point of production, then the majority of the garbage can be processed and turned into compost.

There won’t be as much unsuitable material left over to be sent back to Bloemendhal and will help to prevent build up.

On the Bloemedhal dump, he said that there are about 50 scavengers who sort through the garbage and collect items such as plastic, cardboard and coconut shells. Through the sale of these they generate a daily income of about one thousand rupees, but that sort of sorting is not practical for a dump the size of Bloemendhal which houses 12 years of garbage spanning 17acres. (LP)