Bioreactor Co-Composting Of Sewage Sludge and Restaurant Waste
Composting is an environmental-friendly method to tackle the disposal problem of sewage sludges and municipal solid waste. With appropriate nutrients, porosity, density and moisture content during composting, pathogens such as Salmonella typhi, Escherichia coli etc. will be destroyed and the org...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English English |
| Published: |
2003
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/313/1/549620_FSMB_2004_6.pdf |
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| Summary: | Composting is an environmental-friendly method to tackle the disposal
problem of sewage sludges and municipal solid waste. With appropriate
nutrients, porosity, density and moisture content during composting,
pathogens such as Salmonella typhi, Escherichia coli etc. will be destroyed
and the organic matter will be stabilized producing a compost product that
can contribute directly to soil fertility and conditioning. Composting process
system has been modernized from the heap or windrow system to the
reactor system, which is a comparatively fast process. A 200 liters rotating
drum bioreactor/composter was designed, fabricated and used in this cocomposting
study. This bioreactor was designed in Universiti Putra Malaysia
and was fabricated by Amsea Environment Sdn. Bhd. Three different types
of dewatered sewage sludges, i.e. septic tank, oxidation pond and activated sewage sludges were successfully co-composted with municipal solid waste
in a two-stage process.
The physicochemical and biological characteristics of these municipal
solid waste (restaurant waste) and sewage sludges were measured before
being used as raw materials for the co-composting process. For the
bioreactor composting, the raw materials were fermented for 7 days inside
the 200 liters bioreactor before being matured outside the bioreactor in a
windrow pile until fully matured and ready to be used. A 2:1 (w/w) ratio of
municipal solid waste and sewage sludge was found to give the best initial
C/N ratio for the composting process. The carbon content decreased and the
nitrogen content increased towards the end of the composting process,
which resulted in the reduction of C/N ratio during the composting process to
below 20. The low C/N ratio of the final compost product was very important
as the indicator of compost maturity and stability. The breakdown of organic
materials inside the bioreactor did not increase the temperature to the
thermophilic range (50-60°C), where breakdown of organic matter by
microorganisms is at the optimum rate. In order to overcome the
temperature problem, heated air was supplied to the bioreactor, increasing
the temperature of the composting process. Shredded garden waste was
added as bulking agent. Bioreactor co-composting took around 40-45 days
to produce matured compost. The characteristics of the sewage sludge
compost products were almost similar compared to commercial compost available in the local market and also complied with the United States
Environmental Protection Agency (USEPA) standard. By using bioreactor
system the compost products were improved based on nutrient contents and
duration of composting process. The planting out performance of spinach
with the research compost showed satisfactory results. |
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