Management of Municipal Solid Waste of Bahawalpur City: An Integrated Approach

Abstract

Integrated waste management has been widely accepted as a sustainable approach, and is applicable to solid waste management system in any region. Developed and developing countries, however, undertake different approaches to develop the integrated waste management system. Due to limited data availability, unskilled workforce, financial constraints and lack of expertise in developing countries, the decisions are often based on presumptions rather than objective judgments. Selecting and combining different actions according to the precise requirements of the waste management situation in developing countries and understanding how a specific decision choice fits in a local context is key to identifying sustainable solutions. The study undertook a combined Life cycle assessment (LCA) and Life cycle costing (LCC) approach under the same system boundaries; the objective was to establish the most environmentally and economically feasible alternative for the study area, through comparisons of different waste management scenarios. The scenarios were designed and tested in a life cycle perspective, using a computer based model ―EaseTech‖. All relevant technical and non-technical aspects of existing solid waste management system in Bahawalpur City were determined while the informal sector was also given due consideration in the study. Waste characterization study carried out for one year in ―Bahawalpur‖ city showed significant difference between collected waste (0.274 kg/cap/day) and waste generation rates (0.424 kg/cap/day) due to high source separation activities. Waste generation rates were reported to vary considerably with income groups and seasons. The waste composition analysis revealed organic waste as the largest contributor of household solid waste in Bahawalpur including food waste (44.75%), yard waste (8%), animal excreta (3.6%) and diapers (7.2%), followed by recyclables (27%) including paper (5.9%), cardboard (6.4%), hard plastics (5.36%), soft plastics (2%), glass (3.4%) and metals (1.8%), while the share of inerts including soil and ash is also considerable (9%). From the generated 282.2 tons of waste/day, 58 tons have been minimized at household level. 157 tons of the waste are collected and openly dumped by municipality workers, while remaining lies on the streets or road corners. High scavenging of organic waste and recyclable in Bahawalpur retrieves almost 64 tons of waste daily including 22.6 tons of recyclables. The informal sector in the area is robust. Their societal, economic, environmental and health impacts were studied and weighed for related outcomes. Field surveys revealed that waste pickers are socially marginalized with limited access to the necessities of life, including health services. The study showed a high prevalence of Hepatitis B & C infection in waste pickers (4% & 28%) as compared to non-waste pickers (2% & 6%). The higher incidence of Hepatitis among waste pickers is a function of their occupation involving exposure to sharps and needle stick injuries during waste collection with bare hands. The study acknowledged that the informal waste management sector effectively reduces waste, contributes to the conservation of natural resources and mitigates greenhouse gas emissions while it is proficiently involved in waste recovery activities as well; however, their significant role and aptitude in the supply chain has usually been underestimated. To achieve waste management system sustainability in the study area an important implication is to investigate formal-informal waste management sector integration possibilities. The existing situation and proposed solutions for formal-informal waste sector integration was discussed under a recently developed tool known as ―InteRa‖ (integration radar) rapid evaluation metric and visualization tool. Application of ―InteRa‖ framework illustrated the extent to which local situation is favorable and advocated changes that need to be incorporated to achieve integration in the study area. The baseline scenario depicted the current waste management situation; suggested scenarios were based on four main assumptions, including data collection on waste composition and source separation, use of simple sanitary landfills, organic waste separation for treatment and formal participation of scavengers in the waste management sector. First three scenarios referred to short-range solutions (SRS 1,2 & 3) while scenario 4, 5 & 6 depicted long-standing solutions (LSS). SRS 1 assumed composting of organic waste, while SRS 2 and 3 assumed that gathered waste follows the incineration and refuse derived fuel (RDF) incineration‘s route with energy recovery. LSS 4, 5 & 6 considered the possible integration of formal and informal waste management system with increased collection efficiency. LSS 4 considered material recovery facility (MRF) for recyclable recovery and diversion of organic waste to anaerobic digestion, while LSS 5 and 6 considered the addition of mechanical biological treatment for sorting of waste into different waste fractions and subsequent treatment using RDF incineration. EaseTech calculated environmental impacts of different scenarios for seven impact categories including climate change (CC), human toxicity-carcinogenic (HT-C), human toxicity-non carcinogenic (HT-NC), ecotoxicity-total (EcT), depletion of abiotic resourcesreserve (DAR-R), depletion of abiotic resources-fossil (DAR-F) and particulate matter (PM). The results depict a representation of the input data and relied upon modeled inventory for each process used in the scenarios. The evaluation of the net environmental impacts showed that for SRS, scenario 2 performed in the most environmentally friendly way in five of the seven impact categories except for DAR-R and EcT categories. The baseline scenario reacted better than the other three scenarios in DAR-R category, while worst in EcT category. Scenario 1 appeared to be the worst environmental scenario with most loadings in four (HTC, HT-NC, DAR-R, DAR-F) out of seven categories. While scenario 3 showed better environmental results for ECT and worst for CC and PM categories. In comparison to LSS the baseline scenario appeared to be the best in three categories (HT-NC, DAR-R & PM). Scenario four presented the best environmental performance for only on category i-e; climate change. Scenario 5 appeared to be the worst scenario for PM category and best for HT-C impact category. Scenario 6 contributed most loads in only 1 impact category (CC), performed better than scenario 4 in five impact categories (HT-C, HT-NC, EcT, DAR-R and DAR-F), while presented less loadings than scenario 5 in three impact categories (DAR-R and DAR-F & PM). For HT-C and EcT categories the loadings attributed by scenario 5 and 6 are almost same. The cost analyses for different scenarios were based on the financial calculations of different elements used in these scenarios. The economic evaluation of the entire system showed that the baseline scenario with more manual work and less involvement of technology is cost effective. The second scenario (incineration + energy recovery) was found to be the most revenue generating due to electricity generation and its sale to the grid, while scenario one and three were also found to be economically beneficial nevertheless they are more expensive than the baseline scenario. Reasons include involvement of advanced technology for the collection and transportation of waste and different treatment options including composting, RDF incineration and sanitary landfilling. Among LSS, scenario four is an economically sound option while scenario five is the most expensive one; scenario 6 is interestingly found to have almost equal revenue and expense. The costs of the system are found to increase with increased complexity of the system. The comparative analysis suggests scenario 2 as the best waste management choice among short term scenarios while scenario 6 as the most rational alternative for the study area in long term perspective.