Joseph Tagbo Nwabanne, Christopher Chiedozie Obi 1177 COAGULATION-FLOCCULATION PERFORMANCE OF SNAIL SHELL BIOMASS IN ABATTOIR WASTEWATER TREATMENT Joseph Tagbo Nwabanne, Christopher Chiedozie Obi ABSTRACT The work involves the treatment of abattoir wastewater (AWW) by coagulation technique using snail shell biomass as coagulant. The raw snail shell (RSS) sample and the processed snail shell coagulant (SSC) were analyzed for the determination of the predominant functional groups and surface morphology using Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM) analytical techniques, respectively. Reduction in the turbidity of the effuent was used to assess the performance of the treatment process. The effects of the various factors affecting the effciency of pollutants removal in the coagulation treatment process was studied in a one factor at a time (OFAT) process. A central composite design was used for designing the experiments, building models and determining the optimum conditions. FTIR spectroscopy revealed that the distinctive functional groups of RSS and SSC are amine, amide, hydrocarbons, and ethers. SEM analysis indicated that the processed SSC sample has a well-developed ac- tive site which is not present in the RSS sample. The coagulation-focculation experiments showed that the removal effciency of turbidity of the effuent increases with a decrease in solution pH and increase in coagulant dosage, settling time and temperature. A kinetic study revealed that the removal rate of total dissolved and suspended solids (TDSS) in the effuent showed conformity with the pseudo-second-order kinetic model. In the optimization study, an optimum turbidity removal of 94.39 % was obtained at initial pH of 2, coagulant dosage of 1000 mg/l, settling time of 50 minutes and operating temperature of 50 o C. A second order polynomial regression equation with R 2 value of 0.9985 was obtained in the modeling process. The study has proved that snail shell biomass can successfully be used as coagulant in the coagulation treatment of abattoir wastewater. Keywords: abattoir wastewater, snail shell, coagulation, focculation, turbidity, removal effciency, modeling, optimization. Received 10 May 2018 Accepted 25 January 2019 Journal of Chemical Technology and Metallurgy, 54, 6, 2019, 1177-1188 Department of Chemical Engineering, Faculty of Engineering Nnamdi Azikiwe University, P.M.B. 5025, Awka, Nigeria E-mail: obichristopher27@gmail.com INTRODUCTION Wastewater produced by abattoirs is one of the sources that signifcantly contribute to the pollution of water bodies and the immediate environment. This is be- cause the wastewater is characterized with high organic load as expressed in the reported high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) values [1 - 3]. Abattoir wastewater (AWW) is unpleasant in appearance and offensive in odour. When AWW are discharged on land they constitute land pollution and when discharged in water bodies, this resulted in water pollution which endangers the survival of aquatic live. Discharging untreated AWW will constitute both social and environment challenges. Therefore, there is need for the treatment of the wastewater before discharging it to the environment. Among the different techniques employed in the pri- mary treatment of wastewater, coagulation-focculation technique is preferred due to its capability to successfully reduce the suspended and dissolved particles in waste- waters. Coagulation-focculation has been defned as the process of adding substance (coagulant) to waste effu- ent to make the suspended and dissolved particles bind together (coagulation) and subsequently aggregate into visible focs (focculation) that settle out of the water [4]. The application of coagulation-focculation treatment technique in the treatment of various wastewaters has