BIOLOGICAL TREATMENT OF TANNERY WASTEWATER PRE-TREATED BY COAGULATION USING Moringua oleifera AS NATURAL COAGULANT
TOMKOUANI KODOM *
Laboratory of Water Chemistry, University of Lomé, P.O.Box: 1515, Togo and Laboratory of Environmental Technology, Central Leather Research Institute (CLRI), Chennai 6000 20, India
ABIRAMI BALAKRISHNAN
Laboratory of Environmental Technology, Central Leather Research Institute (CLRI), Chennai 6000 20, India
B. LEKSHMI
Laboratory of Environmental Technology, Central Leather Research Institute (CLRI), Chennai 6000 20, India
PRIYA KANNAN
Laboratory of Environmental Technology, Central Leather Research Institute (CLRI), Chennai 6000 20, India
K. KAMESWARI SRI BALA
Laboratory of Environmental Technology, Central Leather Research Institute (CLRI), Chennai 6000 20, India
KALYANARAMAN CHITRA
Laboratory of Environmental Technology, Central Leather Research Institute (CLRI), Chennai 6000 20, India
MOCTAR BAWA
Laboratory of Water Chemistry, University of Lomé, P.O.Box: 1515, Togo
GBANDI DJANEYE-BOUNDJOU
Laboratory of Water Chemistry, University of Lomé, P.O.Box: 1515, Togo
*Author to whom correspondence should be addressed.
Abstract
Coagulation using Moringa oleifera (MO) seed powder and biological digestion of tannery wastewater were investigated. Coagulation at free pH (1 g MO in 300 mL of Raw Wastewater) removed at least 43.5% of chemical oxygen demand (COD), 65% of suspended solids (SS) and 95.2% of chromium. MO seed powder as natural coagulant does not affect significantly the pH and the conductivity. Subsequent biological treatment was carried out on initial samples and supernatants from the coagulation at static retention time of 2 days maximum (aerobic digestion) and 20 days maximum (anaerobic digestion). 95.2% of COD was removed by aerobic treatment from pretreated wastewater with MO seeds powder. Anaerobic treatment yielded approximately 463.5 mL and 310 mL of biogas during 20 days and 16 days of operation equivalent to nearly 0.259 biogas/g COD removed and 0.264 L biogas/g COD removed for sludge and supernatant obtained after raw wastewater treatment with MO respectively. These results may lead to a reduction in tannery wastewater disposal costs.
Keywords: Moringa oleifera, natural coagulant, tannery wastewater, biological treatment