Removal of nitrogen, phosphate and carbon loads from slaughterhouse effluent by adsorption on an adsorbent based on Ayous sawdust (Triplochyton scleroxylon)
Weldi Gnowe Djonga, Eric Noubissié, Guy Bertrand Noumi
Abstract
Slaughterhouse effluent treatment processes require daily technological adjustments for better efficiency. With a view to combine adsorption to biological treatment, this work aims at evaluating the capacity of simultaneous elimination of nitrogen (NH4+, NO2−, NO3−), phosphates (PO43−) and organic (MO) charges contained in the slaughterhouse effluent, by adsorption on an adsorbent (carbon) made from sawdust Triplochyton scleroxylon (Ayous). To achieve this, the effluent to be treated was sampled in a cattle slaughterhouse in the town of Ngaoundéré. After physicochemical characterization, this effluent underwent various adsorption tests in two reactors operating in batch. Parameters such as the influence of the initial concentration and the initial pH of the effluent, the adsorption capacity of the pollutant load of the slaughterhouse effluent and the contact time were followed during these adsorption tests. The kinetics and absorption mechanisms of organic pollutants, nitrogen and phosphates were modelled. At the end of the manipulations carried out, the results obtained reveal that the average adsorption equilibrium time is 60 min with abatement rates varying between 31% and 52% for the three forms of nitrogen (NO3−, NO2−, NH4+), 40.7% and 52% for organic matter and phosphate respectively. The adsorption of MO, NO3−, NO2−, NH4+ and PO43− on the adsorbent based Ayous is globally optimal at pH 4, and is governed by the pseudo-second order kinetic model. This adsorption takes place both in monolayer and multilayer. The adsorbent made from Ayous sawdust, in combination with the biological treatment will significantly improve the efficiency of the treatment of slaughterhouse effluent.