Bioaugmentation of latex rubber sheet wastewater treatment with stimulated indigenous purple nonsulfur bacteria by fermented pineapple extract|
Kornochalert, Nastee; Kantachote, Duangporn; Chaiprapat, Sumate & Techkarnjanaruk, Somkiet
Background: Treating latex rubber sheetwastewater often leads to the generation of a rotten-egg odor fromtoxic
H2S. To increase the treatment efficiency and eliminate H2S, purple nonsulfur bacteria (PNSB), prepared by
supplementing non-sterile rubber sheet wastewater (RAW) with fermented pineapple extract (FPE), were
used to treat this wastewater under microaerobic light conditions. The following 3 independent variables:
chemical oxygen demand (COD), initial pH and FPE dose were investigated using the Box–Behnken design to
find optimal conditions for stimulating the growth of indigenous PNSB (PNSBsi).
Results: The addition of 2.0% FPE into RAW, which had a COD of 2000 mg L-1 and an initial pH of 7.0, significantly
decreased oxidation reduction potential (ORP) value and stimulated PNSBsi to reach a maximum of
7.8 log cfu mL-1 within 2 d. Consequently, these PNSBsi, used as inoculants, were investigated for their ability
to treat the wastewater under microaerobic light conditions. A central composite design was used to determine
the optimal conditions for the wastewater treatment. These proved to be 7% PNSBsi, 0.8% FPE and 4 d retention
time and this combination resulted in a reduction of 91% for COD, 75% for suspended solids, 61% for total sulfide
while H2S was not detected. Results of abiotic control and treatment sets indicated that H2S was produced by
heterotrophic bacteria and it was then effectively deactivated by PNSBsi.
Conclusions: The stimulation of PNSB growth by FPE under light condition was to lower ORP, and PNSBsi proved
to be effective for treating the wastewater.
Bioremediation; Fermented plant extract; Response surface methodology; Rotten-egg odor; Rubber wastewater