STUDIES ON USE OF CARBON SLURRY, A WASTE FROM FERTILIZER PLANT, IN TREATMENT OF WASTE WATER

Abstract

Non biodegradable materials like heavy metals, refractory organics are not removed during the conventional treatment process. In order to meet the regulatory standards and for safe disposal, it is necessary to go for tertiary treatment. Various tertiary treatment methods include adsorption, membrane separation process, ultra filtration, reverse osmosis etc. Adsorption has been found to be efficient for the removal of most of heavy metals in waste water at lower concentrations. Activated carbon is commonly used adsorbents, however, due to its high cost and loss in regeneration, various low cost adsorbents have been investigated during recent years. The aim of the present work is to explore the possibility of utilizing carbon slurry, which is produced during partial oxidation of hydrocarbons,for the treatment of industrial waste water. In the present work carbon slurry has been used for the treatment of heavy metals like Cr(vi), Ni(ii), Zn(ii) which are present in fertilizer plant waste water. Carbon slurry has also been used for treatment of three industrial waste effluents from phenol formaldehyde resin, polyester plant and sugar industry. Proximate analysis, chemical analysis, particle size analysis, surface area determination, XRD and SEM studies were conducted for characterizing the carbon slurry. Batch studies were conducted to see the effect of contact time, adsorbent dose and initial concentration on removal of Cr(vi),Ni(ii) and Zn(ii). Equilibrium data were fitted in Langmuir and Freundlich isotherms. Removal to the extent of 90% was achieved for Cr(VI), and 85% for Ni(II) and iii Zn(II) using carbon slurry as adsorbent. Hence carbon slurry has good adsorptive capacity for Cr(vi), Ni(ii) and Zn(ii).Kinetics of removal has also been presented, which shows that removal follows first order kinetics. Weber and Morris plot show that intra particle diffusion is the rate controlling step. Some studies on the competitive • adsorption of heavy metals (Cr(vi),Ni(II) and Zn(II)) in multi cationic solutions have been carried out.lt is found that chromium is readily adsorbed in comparison to nickel and zinc in a waste water containing all three. Experiments were carried out for the removal of COD of waste water from polyester industry waste, phenol formaldehyde resin plant and sugar mill effluent and results show that carbon slurry is suitable substitute for activated carbon. Adsorption of Cr, Ni, Zn was found in the order Cr>Zn>Ni.