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Treatment of wastewater from biodiesel plants using microbiological reactor technology
Khan, Y.; Yamsaengsung, R.; Chetpattananondh, P. & Khongnakorn, W.
Abstract
The objective of this paper was to introduce the
aerobic microbiological reactor technology for wastewater
treatment of biodiesel plants and find out the key factors
that are involved in membrane fouling. The research was
carried out in two steps. In the first step, sulfuric acid of pH
2, 2.5 and 3 was added to biodiesel wastewater and significant
reduction in organic pollutants was observed at pH
2.5 such as chemical oxygen demand, and oil and grease
were found to be 74–84 and 84.2–92.6 %, respectively. In
the second step, microbiological reactor was operated at
different hydraulic retention times of 15, 12, 9 and 6 h
along with an increase in organic loading rates (range
1–3 g/L day) on individual hydraulic retention times.
However, overall chemical oxygen demand and oil and
grease removal efficiency remained in the range of
91.7–97.20 and 95.5–97.9 %, respectively, throughout the
experiment, while severe membrane fouling was observed
with decreasing hydraulic retention time due to decrease in
dissolved oxygen concentration and increase in mixed
liquid suspended solids, and soluble microbial product
containing protein and polysaccharide. At lower hydraulic
retention time of 6 h, an increase in particle size was
reported as 27.9–62.7 μm, and soluble microbial product
containing protein and polysaccharide reported as 20–60
and 19–59 mg/L, respectively. Higher soluble microbial
product level led to increase in particle size with irregular
shape, which led to severe membrane fouling.
Keywords
Biodiesel wastewater treatment; Membrane fouling; Microfiltration; Oil-rich phase; Submerged membrane bioreactor
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