ABSTRACT
Abattoir wastewater generated from various meat processing operations in several developing countries pose a serious threat to the environment. Consequently, there is urgent need to reduce the impact of environmental pollution from it. Coagulation techniques have been recommended and used by many researchers successfully in treating wastewater, therefore an investigation of possible use of chito-protein extracted from crab shell (locally sourced) was used as a coagulant for treating abattoir wastewater. Coagulation experiments were carried out using jar-test procedure to investigate the influence of pH, time of settling, temperature and adsorbent dosage for coagulation of BOD, COD, Turbidity and Colour from the wastewater sample. To determine the interaction effect of the various process variables, Response Surface Method (RSM) was used in the optimization of the process variables. To determine the effectiveness of the coagulant, pre and post characterization of the wastewater samples were undertaken, the result of the post characterization of the wastewater sample indicated that most of the water quality parameters except Iron were within WHO standard. The Total Suspended Solid (TSS), for instance stood at 564.6 mg/L and 29 mg/L respectively for pre and post characterisation, the value of 29 mg/L of the post characterization was below the WHO recommended value of 30 mg/L. The predicted responses and the experimental values correlated significantly, an indicator that RSM optimization method used in this study is suitable in modelling the process variables. The result of the study further shows that optimum process variable is dependent on the solution pH (acidic), coagulant dosage of 2-3g, settling time of 25-30 min and operating temperature from 323K to 333K. The coagulant used in this study, when compared with previous studies have shown to have strong potential for use as a coagulant and as an alternative to chemical coagulants in the treatment of abattoir wastewater.
ABSTRACT
Wastewater from slaughter houses (abattoirs) has been a problem in Nigeria. It is complex and difficult to treat. The potentials of novel Fish Bone Chito-protein (FBC) successfully extracted through de-proteinization of Fish Bone Flour (FBF) were explored for the reduction of particle load in abattoir wastewater. Extracted FBC sample was analysed via proximate analysis and instrumental characterizations viz: X-ray Fluorescence (XRF) analysis, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectrophotoscopic Analysis (FTIR). Influences of coagulant dosage, pH, settling time and temperature were studied. The rate of particle uptake was studied using seven kinetic models. Proximate characterization of FBC revealed that it contains 24% protein, 43% carbohydrate and other components in trace values. Before treatment, abattoir wastewater contains (563 mg/L) suspended particles in excess of the national discharge standard. 92% of the particle load was removed after the coagulation treatment with 1.5g of FBC, after 35 min at pH 2, and 40 °C. BOD removal of 58% was also obtained at the same conditions. The best kinetics model selection was done between Pseudo Second Order (PSO) and fractional power (FP) kinetic model via one way statistical mean comparison using ANOVA and turkey pairwise p-values. The ANOVA p-value for pseudo second order (0.001) was found to be Ë 0.005 (model significance alpha value). Also, the difference between the adjusted and predicted R2 value (0.0018) was less than 0.2. Thus, pseudo second order described the kinetic data with precision. The mechanistic pathway analysis for the process particle uptake was governed by intra-particle diffusion and film/surface diffusion. The results summarized indicate that fish bones are no waste, FBF is good source of coagulant.
