Date of Award

Fall 12-20-2020

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

Advisor

Jean MacRae

Second Committee Member

Kate Beard

Third Committee Member

Travis Blackmer

Abstract

As per US EPA, in 2017, 41 million tons of food waste was generated, but only 6.3% was diverted from landfills (US EPA, 2020). When landfilled or incinerated, organic waste (food waste, sludge, manure, agricultural waste) causes environmental pollution through greenhouse gas emissions, land, water, and air pollution. In contrast, if we compost or digest organic waste, we can generate soil additives and a mixture of methane and carbon dioxide gas to produce electricity or energy. Both digestion and composting reduce greenhouse gas emissions, improve the land through additives, and boost the economy. Many countries are adopting anaerobic digestion and composting to handle organic waste. There are currently 250 anaerobic digesters in the US (Pennington, 2018). There are 1200 wastewater recovery facilities in the US with anaerobic digestion, and approximately 20% of them co-digest sludge with other organic materials (Pennington, 2019). Meanwhile, the process of anaerobic digestion is chemically and biologically complex. In 2018 alone, as per EPA, eleven anaerobic digesting facilities were shut down (Pennington, 2019). There were various underlying factors such as; lack of feedstock, economic infeasibility, system shock, hampering the sensitive areas like wetlands through leaching from the storage areas. Thus, while starting a facility, there are many factors to consider for its long-run success. One of the most crucial factors to consider is the site location. Social acceptance, economic viability, job opportunities, and environmental disturbance are all site-dependent. Hence it is critical to optimize the choice. This study used ArcGIS Pro 2.6 to find the optimum location for organic waste management facilities in Maine. There are three anaerobic digesters in Maine, of which one is currently closed, and approximately 92 composting facilities handle a large amount of yard trimmings and some food waste. Most of the composting facilities are small scale with 4.3% composting food waste and 4.3% composting sewage sludge. In this study, data on food waste, manure, and sludge were gathered from Maine DEP, EPA, US Farms Data, and published reports to estimate the approximate amount of organic waste. A capture rate of 20% was used for food waste to estimate the amount of food waste collected. For the analysis, four scenarios: (1) the largest anaerobic digester (Fiberight) does not resume, or (2) resumes its work, and (3) co-digesting waste with or (4) without sludge were taken into consideration. To be more area-specific, the analysis was done for the Maine Department of Transportation (DOT) regions: Eastern, Northern, Southern, Mid-Coast, and Western Regions. Eight criteria- food waste availability, sludge availability, transportation cost, distance from residential areas, slope, land cover, distance from airports, and environmentally sensitive areas like conserved lands and wetlands were used to find the optimum locations. Analytical Hierarchy Process determined the criteria weights before assigning them in the suitability modeler of ArcGIS Pro to find the optimum locations. By transforming these criteria, the five best locations in Maine and three possible optimum locations in each region for each scenario were identified. Opportunities for the upgrading of existing farms with excess manure, transfer stations, composting facilities, and WRRFs were identified. The facilities that coincide in all the scenarios are the optimum facilities that work in all scenarios. Hence feasibility study can be started on those facilities. In the Northern region, Caribou WWTF and Pinelands Farms Natural Meats Inc. coincide in all scenarios, making them the best existing facilities that could be upgraded in the future. Similarly, in the Eastern region, the transfer station of the Town of Lincoln, and the Dover Foxcroft WRRF coincide in all scenarios, making them the best existing facilities that could be upgraded in the Eastern region. Four farms and the transfer station of the town of Clinton coincide in all scenarios in Mid-Coast. Out of these four farms, Stedy Rise farms and Caverly Hills LLC are 330 acres and 840 acres and generate excess manure of 4096 tons /year and 4175 tons/year. These farms could be good locations for a new facility using food waste. In the Southern region, no single facility was identified in all the scenarios, but Sanford WRRF and a few farms could be chosen for feasibility analysis. In the Western region, six farms and the transfer station of the town of Turner coincide in all the scenarios. Feasibility analysis can be done in these facilities to determine which can be upgraded as a new waste management facility utilizing food waste.

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