Sorting and Recycling Municipal Solid Waste (MSW) in Xiamen City, China - Case Study

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Courtesy of TOMRA Sorting (TITECH)

TOMRA Sorting Recycling is playing a pivotal role in the implementation of automatic sorting at the MSW plant in Xiamen

Background

The city of Xiamen, renowned for its natural beauty, is located on China's southeast coast, in Fujian Province. Its famous seascape and clean natural environment are a magnet for tourists, and the city government wants to keep things that way. As a result, Xiamen is a leader, both in China and globally, in environmental policy.

It's this ecological farsightedness that prompted the city, sometime around year 2,000, to consider the situation with regard to Municipal Solid Waste (MSW). At this point in time, MSW was mainly landfilled. However, the city government wanted to preserve Xiamen's natural good looks and, along with them, the valuable natural resources that were being thrown away with the city's trash.

As a result, within a year, the city's Municipal Bureau of Garden Management proposed that the Municipal government should build a plant for the sorting of MSW, with the aim of recovering recyclables and organic materials for biological treatment.

Several companies submitted bids for the project, and the company Xiamen Alee was finally selected to operate the MSW sorting plant for a period of 25 years, based on a Build-Operate-Transfer (BOT) contract. After thorough analysis and extensive discussion of how best to handle Xiamen's MSW, Xiamen Alee subsequently improved the plant's operational procedures. The decision was made to pre-sort the MSW and use the sorted organic materials for anaerobic fermentation in order to generate methane gas, which would then be used to generate power.

In 2010, the Xiamen Alee MSW plant received some financial aid from China's Central government and was listed as a demonstration project of China's Ministry of Housing and Urban-Rural Development (MOHURD). Clearly, both local and central government were intent on a model, a proof-of-concept, of what breakthrough leadership in environmental protection could achieve.

In 2011, the first pre-sorting lines of the MSW plant had been completed, but they relied mainly on manual sorting, with machines used only to a limited extent. In 2012, Alee obtained the crucial financial support of the Ministry of Industry and Information Technology (MIIT) and proposed to improve the Xiamen plant with automated sorting using sensor-based sorting technology. The goal was to increase the sorting capacity of the plant, improve the working conditions of the sorting employees and reduce sorting costs.

TOMRA participated in the bidding for the automated sorting project and was not slow to recommend solutions. Finally, following some intense technical discussions, TOMRA's solutions were adopted as the way forward for the updating of the Alee MSW plant.

Implementation

TOMRA’s automated sorting machines were duly delivered to Alee in 2013 and installed for pilot operation. Since the MSW contained a large amount of organic materials, the TOMRA China team conducted an analysis of the constituents of the Alee MSW. The results indicated only a low amount of metals, paper and PET bottles, but there was, however, a considerable amount of PE film and mixed hard plastics. Hence these plastics were targeted for automatic sorting for recycling.

In addition, the MSW stream contained a lot of inert materials such as stones, bricks, glass and sea shells. These accumulated in the anaerobic fermentation cell and over time reduced its capacity and increased maintenance costs dramatically. TOMRA duly recommended use of the X-TRACT system to separate these 'inerts' from the organic material.

Following cleaning, the organic material proceeds to an anaerobic fermentation cell. Here methane gas is produced, which is used for generating electricity. The fermentation process can also enable the production of fertilizer. Xiamen's municipal garbage is now being put to good use.

In the sorting plant, burnable materials are sorted for use as refuse-derived fuel (RDF), which can be used as an alternative energy source in power plants or cement kilns.

The TOMRA machines have now been in successful operation for over two years, and this demonstrates that the TOMRA automated sorting machines are well-adapted to the sorting of complex MSW in China.

The BOT arrangement

The Xiamen MSW plant is a Build-Operate-Transfer (BOT) agreement between Alee and the Xiamen Municipal government, according to which the MSW plant will be operated by Alee for 25 years, prior to its eventual ownership by the Municipal government. The total investment, on the part of Xiamen Alee, was RMB206 million. The Xiamen Municipal government provides about 500 tons of MSW waste per day for sorting, recycling and processing at Alee and pays Alee a fee based on the actual MSW amount.

Alee’s other income sources include the recycling of the PE film, hard plastics, metal and glass; the methane and the electricity derived from it; the fertilizer generated from the organic material; and the RDF derived from the waste. What is good for the environment is clearly good for business.

The TOMRA sorting solution

TOMRA provided Alee with five AUTOSORT machines and one X-TRACT system. The AUTOSORT units are used in two sorting lines, and these are finally combined into a single line that uses the X-TRACT.

Alee's choice of the TOMRA Sorting Recycling systems was based on TOMRA's leading international experience and the cutting-edge design of its advanced machines, which combine scientific sorting technology with a rugged reliability in operation. As well, TOMRA was able to provide exhaustive information about other MSW use cases, for reference. TOMRA consistently demonstrated a professional level of service while undertaking the initial MSW content analysis and recommending various possible solutions – providing full support.

Several features of the TOMRA systems proved particularly important for the Xiamen MSW operation. The MSW content in Xiamen is very complex. It is wet and contains a lot of organic materials. TOMRA machines have, in the past, been installed in the US and Europe, where the MSW is drier and contains less degradable organic material. Nevertheless, the TOMRA team proceeded to adjust and optimize the sorting processes and programs, based on their analysis of the Xiamen MSW. In short, the TOMRA sorting machines were successfully adapted to the challenging sorting requirements of the Xiamen Alee plant.

The field-tested and highly stable operation of the Alee plant proves that the TOMRA machines are capable of adapting to the different sorting streams of different markets. Much invaluable first-hand data and experience have been accumulated by TOMRA in the process of supporting the Xiamen Alee operation, and this will prove immensely useful for similar operations across China.

The TOMRA machines not only proved stable and reliable in operation, they achieved a high rate of both throughput and recovery, resulting in high-purity sorted materials, while providing a good working environment for their operators.

The TOMRA advantage

The latest-generation AUTOSORT system utilizes NIR (near infrared) scanning technology, and it is the first NIR system not to require an external light source. FLYING BEAM® technology, a fundamental innovation in sorting system design, enables the AUTOSORT to operate without external lamps, illuminating only the area of the conveyor belt being scanned. A 1-meter wide sorting unit uses only two 55W lamps – in total, 110W. This results in an energy savings of up to 70%, for a reduced carbon footprint and associated cost savings. In short, the AUTOSORT is the most energy-efficient sorting system of its kind available today.

The MSW in Xiamen is very wet (60-65%) and this makes the operating environment a considerable challenge. In an environment that most sensor-based sorting units would find problematic, the TOMRA sorting units proved they could function well – clearly a result of their being designed for ease-of-maintenance and equipped with self-cleaning and automatic warning systems.

Building for the future

Equipped with TOMRA's advanced sensor-based automatic sorting systems, Xiamen Alee, in cooperation with Xiamen's Municipal government, is committed to protecting the environment and maintaining the sustainable development of the city.

Xiamen Alee is now on a 25-year mission to operate the sorting plant and in this process, with support from TOMRA Sorting Recycling, optimize its business experience and reputation, while preserving the environmentally friendly image of Xiamen.

Testimonial

'Both myself and my colleagues here at Xiamen Alee are immensely pleased and proud to have this opportunity of playing a central role in an operation that will have immense environmental benefits and directly support China's drive for sustainable development,' said Liu Junxiao, Chief Engineer at Xiamen Alee. 'TOMRA's automated sorting equipment is among the most advanced of its kind in the world and we are absolutely committed to working with both TOMRA and our Xiamen customers to make waste sorting and recycling work in Xiamen. In the process, our goal is to recover valuable material resources, add value, promote sustainability and protect Xiamen's famous natural environment. We are confident that the Xiamen plant is an example from which other cities in China can learn.'

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