Analysis and design of solid waste management system for a residential zone of Dhaka City

Abstract

Dhaka, the capital of Bangladesh, with an inhabitant close to 10 million, undergoes regular environmental problems, which are linked to inefficient solid waste management system. The objective of the study was to establish the waste generation rate of Banani, Gulshan Baridhara and lJttara Model Town area to plan an efficient solid waste management system. The other major objectives were analysis and design of solid waste management system with an emphasis on collection and disposal and to determine appropriate methods and means to Improve collection and minimization of cost of collection, transport and disposal of solid waste. Domestic waste generation rate was estimated from Sector-4 of lJttara Model Town through house to house collection by rickshaw van. Population of each household was also determined from questionnaire survey. Commercial waste from five Chinese restaurant of lJttara model town. Hospital wastes from one private medical college hospital and three clinics were also collected. Street sweepings, a significant waste volume were also determined from different locations of lJttara model town. Domestic waste generation rate was found to be 0.60 kg/cap/day, commercial wastes 0.55 kg/cap/day, clinical wastes 1.75 kg/cap/day and street sweeping wastes 0.16 kg/ meter/day. Due to resource constraint in collecting samples from door to door, and due to constraints in analyzing the samples in the laboratory the sample size was kept purposefully small and may not be statistically representative of the study area. Thus, the results obtained on generation rate should be used with caution remembering that these data will be more applicable for the areas and the communities having same characteristics as the study area. Physical composition analysis of domestic waste shows that major portion is food waste (72.5%) and polythene is the second largest fraction(l3.70%). Waste stream analysis shows 58.70% domestic, 7.90%. commercial, 0.32% clinical and 33.08% street waste. Monitoring well were installed at Matuail and Mugdha landfill. Leachate samples were collected and analyzed at Environmental Engineering Laboratory. Analysis of ground water near landfill site (about 300m average) found to be free from contamination. It may be concluded that the presence of natural clay under the fill acts as a sealer and protects the aquifer. From cost analysis it was found that transportation cost is about 49%, primary collection is about 31%, disposal is about 20%. DCC's 75% cleaners are engaged in street sweeping actives who are under utilized and consuming major portion of yearly allocation. Street sweeping waste collection cost is 8 times higher than the primary collection cost. It was also found that house to house domestic waste collection and street sweeping by private contractor were less costly, than the present practices of DCC. Demountable container carrying trucks were underutilized in zones 1,2,3,4 and 5. This indicates that transportation by 5 ton capacity open truck may be cheaper than 3 ton capacity demountable container trucks. Installation of modified transfer station at Gulshan area may be economical compared to the present operation of transporting each truckload of waste to the Matuaillandfill area. It was also found that formal practice of resource recovery and recycling could earn approximately Tk. 71.91/ton of solid waste.