M.S. Thesis: Optimizing Sustainable Waste Management in Shenzhen, China.

By Yiran Song

Advisors: Prof. Nickolas J. Themelis and Dr. A.C. (Thanos) Bourtsalas

Department of Earth and Environmental Engineering
Fu Foundation School of Engineering & Applied Science
Columbia University

December 2017

The rapid economic development and urbanization in China during the last few decades have brought municipal solid waste (MSW) management problems to prominence in all cities. Megacities like Beijing and Shenzhen had once faced garbage and open dumpsites surrounding the urban area. As the cost of urban and suburban land turned unaffordable for landfilling, the central government and municipalities started to support and enforce the development of MSW treatment facilities, especially by means of waste-to-energy (WTE) plants. In 2017, over 250 WTE plants were in operation in China, treating approximately 38% of the overall collected MSW.

As the development of WTE technologies matures and sufficient capacity of treatment plants was established, additional facilities on top of the existing resources are looked into. Opportunities of existing WTE plants or cement plant plus pre-treatment facilities, such as Material Recovery Facilities (MRF) or Mechanical Biological Treatment (MBT) plants, are reliable in magnifying treatment capacity and gain recovered material at lower capital costs than building more WTE plants. Policies that provide incentives for waste synergy projects, for example, simple MRF and cement plant, have started to gain wide adoption.

This thesis includes preliminary financial and environmental analysis of WTE plants, cement plants, and pre-treatment facilities (MRF or MBT) combination options in Shenzhen, China. The target WTE plant is the Shenzhen East WTE plant, which will be the largest WTE plant in the world, starting at the end of 2018 and treating 5,000 tons (t) per day. The target cement plant is China Resource Shenzhen Cement Plant which China Resource has successfully operated using waste-derived fuels in Guangxi Province. All scenarios show that the combined plants are capable of providing promisingly high financial returns via material recovery or bottom ash recovery, biogas and electricity generation, and gate fee revenues. The use of MRF with either existing WTE or cement plants is more profitable than the MBT process. due to significantly lower capital cost and high material recovery return. When the WTE plant operates with no pre- treatment facility but including bottom ash recovery technology, it is more profitable even at though it has a higher capital cost. However, all the profit scenarios must rely on a stable electricity price and secondary market, as electricity and recovered material sales are the largest two revenue sources. Moreover, the environmental benefits are significant and have a compound effect in the long run. Also, all the materials-energy combination options can conserve land and abate millions of tons of greenhouse gases, by diverting waste from landfills.

In the long run, public recognition and participation are crucial to moving from landfill to WTE upward to composting and the 3Rs (reduce, recycle, reuse) in the sustainable waste management hierarchy. Also, the government must consider including the informal recyclers to the formal sector as the residents are familiar with these recycling professionals over the years. Ways of inclusion can be employed as waste sorters at pre-treatment facilities, waste managers in the housing estates for regulation compliance, and providing informal recyclers with uniforms and equipment that connect them with the communities. Only in this way, implementing both short- term and long-term action plans, the goal of attaining proper waste segregation and 35% recycling rate; both of which require public participation that can be achieved within the next few decades, thus moving towards the entire society to the circular economy and sustainable waste management.

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