Adsorption of COD and BOD from Slaughterhouse Wastewater Using Stabilized Solid Waste Materials

Investigation on the use of agricultural and industrial wastes as locally available and economically viable adsorbents for wastewater treatment has been a focal point of studies in recent times. Consequently, landfill mining has become viable as a way of discovering the potential of recycling such materials. The stabilized solid waste used in this study was obtained from a closed landfill site of over 10 years which has become stabilized due to years of placement. Raw undiluted wastewater sample was collected twice weekly for eight weeks from a local chicken slaughterhouse located in a suburb area in the city of Selangor, Malaysia, close to the University Putra Malaysia. The samples were collected from the sewer at different times and alternate days covering all the days of the week to ensure that a good distribution of sampling was done. The initial concentrations of COD and BOD were 2720 mg/L and 960 mg/L, respectively. The result exceeded discharge guidelines according to Malaysia Environmental Quality Regulation (2000) for effluent discharge and therefore not suitable for direct discharge to the water streams without prior treatment. However, after treatment, the residual concentrations were 160.2 mg/L for COD and 54.9 mg/L for BOD, achieving removal efficiencies of 94.8% and 95%, respectively. The treatment was carried out at ambient temperature and pH of 6.0 in less than 120 minutes with dosage of 8 g/100 ml at 250 rpm. Both Langmuir and Freundlich isotherms were used to fit experimental data and the Langmuir model gave better correlations of r2 values close to 1, (0.9999 and 0.9999) Langmuir, and (0.9785 and 0.9557) Freundlich for COD and BOD. However, in terms of the amount of pollutants adsorbed (Qe), the Freundlich model gave higher values which shows that the Freundlich model best describes the process as heterogeneous. In conclusion, the stabilized solid wastes material shows good potential to be used as an adsorbent, moreover, as a low-cost alternative for wastewater treatment as far as the optimal treatment conditions are well maximized.