Optimization model for integrated municipal solid waste management in Mumbai, India

GROUP 9

Amiya Mohan Dash 5BArpit Gupta 11BFirdaus Khan21BNilkancha Badhiye32BSanish Nair41B

Optimization model for integrated municipalsolid waste management in Mumbai, IndiaBACKGROUNDMumbai, the largest metropolitan city in India, presents one of the most critical Solid Waste Management (SWM) systems.

An increase of 20%An increase of 41%Community Compost Plant

Mechanical Aerobic Compost PlantHHRag pickers of NGOsBiodegradable Recyclable SellLandfillCompost HHCompost PlantCompost Inert Materials LandfillDecision Variables

Generation node iMechanical aerobic composting aCommunity compost plant vSanitary landfills o

Decision variables waste transported from toWia generation node i Aerobic compost plant aWiv generation node i Compost plant vWio generation node i Sanitary landfill oWao Aerobic compost plant a Sanitary landfill oWvo Compost plant v Sanitary landfill oOptimization function

The objective function includes minimization of net cost of integrated solidwaste management (ISWM) system

Minimi ze(CT BT)where,

CT is total cost associated with ISWM stream, and CT includes cost associated with : 1. Aerobic CompostingCAa2. Community CompostingCVv3. Sanitary Landfill CODo

BT is total benefit associated with ISWM stream, where BT consists of benefits derived from, 1. Aerobic CompostingBAa2. Community Composting BVv

Cost of Waste Processing at Aerobic Composting Plant aTransportation Cost to CompostOperating Cost at CompostLand Cost at CompostEnvironmental Cost at CompostLand Cost at LandfillOperating Cost at LandfillEnvironmental Cost at Landfillcoll= cost of collection of wastet=Transportation cost of waste per ton per kmDia=Distance between generation node i and aerobic compost aoca=Operating cost per ton of waste for aerobic composting plantlca=Land cost associated with aerobic compostingenvca=Environmental cost per ton of waste for aerobic compostingocod=Operating cost per ton of waste for sanitary landilllcod=Land cost associated with sanitary landfillenvcod=Environmental cost per ton of waste for sanitary landfill

Cost associated with LandfillLand Cost at LandfillOperating Cost at LandfillEnvironmental Cost at landfillTransportation Cost to landfillcoll= cost of collection of wastet=Transportation cost of waste per ton per kmDio=Distance between generation node i landfill oocod=Operating cost per ton of waste for sanitary landilllcod=Land cost associated with sanitary landfillenvcod=Environmental cost per ton of waste for sanitary landfill

coll= cost of collection of wasteocv=Operating cost per ton of waste for community composting plantlcv=Land cost associated with community compostingenvcv=Environmental cost per ton of waste for community compostingocod=Operating cost per ton of waste for sanitary landilllcod=Land cost associated with sanitary landfillenvcod=Environmental cost per ton of waste for sanitary landfillt=Transportation cost of waste per ton per kmDvo=Distance between generation node i and landfill o

Cost associated with Community Composting PlantOperating Cost of Biodegradable WasteLand CostEnvironmental Cost of the Biodegradable WasteLand Cost at LandfillOperating Cost at LandfillEnvironmental Cost at landfillTransportation Cost to landfill

Benefits are derived from recyclable material and compost produced from community compost plants and aerobic compost plants

BAa =total benefits of waste processing at aerobic composting plant aBVv=total benefits of waste processing at community compost plant vBCODo =total benefits of waste management under sanitary landfillBT =total benefits of waste managementfrr=fraction of recyclable material r in total wastepca =price of aerobic compostpcv =price of community compostfca =compaction factor for aerobic compost plantfcv =compaction factor for community compost plantprr =price of recyclable material r

CONSTRAINTSMass balance constraintsAll solid waste generated at a source i, should be transported either to a community compost plant v or to an aerobic compost plant a, or to a sanitary landfill o. Wiv + Wia + Wio = Gi

Capacity limitation constraintsPlanned capacity at each facility should be less than or equal to the maximum allowable capacity of the facility.Wia = fin * Wiafin=fraction of inert material in total wastev a oii10Application of Optimization Model

Assumptions:Every generation node has a community compost plant.Three disposal sites have been considered in the model.Aerobic composting plants are situated near every disposal site so that cost of transportation of inert material is negligible.

No. of generation nodes : 24No. of Aerobic Composting Plant : 3

Generation node (i) = 24 (municipal wards)Aerobic composting plant (a) = 3 (one near every dump site)Compost plant (v) = 24 (one in every ward)Sanitary landfills (o) = 3Number of decision variables = (ia + iv + io + ao + vo) =(243 + 2424 +243 +33 +243) = 801Number of constraints = I+v+a+2 = 53

Estimated Cost and Benefits FiguresFurther assumptions:The optimization model is solved using BDMLP solver in GAMS. The following assumptions are made to obtain the optimal solution:1. Households segregate waste into organic and recyclable material and there would be no additional cost associated with it.2. Volume reduction factor for composting assumed to be 0.25.3. Rag pickers in Mumbai for the year 200001 is estimated to be 26,444 to 59,500. Each rag picker picks up 12kg of waste everyday.

The optimal strategy in this case is, all waste is processed at communitycompost plants and only inert material is transported to dump site. Hence,community compost plant becomes the dominant option. Here communityemployees collect segregated waste from households. Recyclable materialis sold to wholesalers and organic material is composted and then sold inthe market. All inert material goes to the municipal bins, which is latertransported by the MCGM to disposal sites.Optimal SolutionSensitivity analysisScenario I: Introducing cost for segregation of waste with community participation.Collection cost of Rs. 700 ($16) per ton is imposed for the community compost plant.

Scenario II: This scenario assumes that there is no revenue obtained from compostScenario III: Environmental costs associated with all the waste management options are neglected.

1. Cost of segregation of waste with community participation is Rs. 700($16) per ton.2. No revenue is incurred from compost.3. Environmental costs associated with all the options for wastemanagement are neglected.