Municipal Solids Waste Composting Demonstration Project in Housing Estates - Phase III of the Green Community Pilot Scheme  

Project Title: Municipal Solids Waste Composting Demonstration Project in Housing Estates - Phase III of the Green Community Pilot Scheme

Applicant: Hong Kong Baptist University (Dr Jonathan Wong)

Total Approved Grant: $138,000

Duration: 1/7/2002 - 30/6/2003

Project Status/Remarks: Completed

To demonstrate to housing estate residents the re-utilization of the organic fractions remaining after the "Waste Separation and Recycling Project" for the purpose of providing organic fertilizer. It is expected that public awareness of waste minimization and protection of natural heritage can be achieved.

Summary of the Findings/Outcomes :

The commercial composter tested in the present study could be used to compost vegetable and food waste with a maximum daily treatment capacity of about 50 kg. It is a self-contained in-vessel composter with automated mixing and temperature control, resulting in uniform aeration and temperature through out the composting mass. The optimized composting conditions and the microorganisms inoculated significantly improve the degradation efficiency of the organic matter in the food waste. Over 90% volume reduction and 70% weight reduction could be achieved in the optimization trial. It may not be possible to use the final product from this process like other commercially available compost, since the salt content of the compost was high. A controlled application rate should be recommended in order to reduce the impact of salinity on seed germination and plant growth. After the laboratory composting trials, a composter was installed in the Un Chau Estate to evaluate the feasibility of performing composting trial using this commercial composter in pubic housing estates and its acceptability by the residents. The programme received a constant support from about 30-60 families. On average a total of about 36 kg of waste was collected every evening and composted in the composter. It shows that an intensive programme like the present one could encourage communities to adopt environment friendly methods. Composting provides not only a cost effective but also an environment friendly alternative to landfilling. The participation could be initially encouraged by target specific environment education, awareness programmes and also through incentives. It should be noted that the composter used in these trials were small scale commercial composters and are more suitable for small institutions like a college/University cafeteria, schools, correction homes, etc. The final quality of the compost varies depending upon the nature of food waste input, so its usage should be done after considering its characteristics.