REMOVAL OF PHOSPHATES FROM WASTE WATER BY ADSORPTION

Abstract

In the past few decades, excess phosphate has been recognized as a non-point-source agricultural pollutant throughout the world due to the over application of both synthetic and animal-based fertilizers, detergents, pigment formulation, water treatment, and mineral processing. Phosphates discharged into the receiving water streams sometimes act as a major nutrient for aquatic life that may lead to overgrowth of algae (eutrophication) in stagnant water bodies like lakes and ponds. This affects the water quality through consumption of dissolved oxygen, destroys aquatic life. Removal of ---- phosphate from wastewater is therefore necessary to meet the discharge limit to control eutrophication. The Indian discharge limits for phosphate [P043] is 5.0 mg/l as [P]. The principal forms of phosphate being orthophosphate, pyrophosphate and tripolyphosphate, together with smaller amounts of organic phosphates. To meet the effluent quality standards, the removal of phosphate from wastewaters prior to discharge into natural waters is required. In wastewater treatment technology, various techniques have been used for phosphate removal such as electrolytic method, ion exchange, precipitation, reverse osmosis, biological process, etc.; but adsorption still continues to he most widely used process because of its safe, environment friendly and easy process. Phosphate removal from waste water was carried out by using H2SO4-activated carbon developed from coir pith, an agricultural solid waste. Studies were conducted to delineate the, effect. of enntart time. adsnrhent dose; nhnsnhate r,nnr_.entrat;en nN _ind temperature. Characteristics of the activated carbon are done by SEM process and proximate analysis. The extent of adsorption and reduction processes depends on the porous texture, nature and preparation procedure of activated carbons. The equilibrium data could be described well by Langmuir and Temkin isotherms. Thermodynamic parameters were also calculated