usage of natural adsorbents for cod removal of industrial wood fiber wastewater

today the industrial wastes are one of the main problems in the developing countries. discharging the industrial wastewater into environment is harmful for human health and other living creatures.thus decreasing of the pollution load of waste waters is an important environmental issue.adsorption of chemical oxygen demand by biomass wastes can be a proper and low cost method for cod removal from industrial wastewater, since these materials are abundant in nature and useless. the use of carbon prepared from date pits and nutshells capacity to adsorb cod from aqueous solutions are studied.the purpose of this study is to determine optimum conditions for adsorption of cod of fiber wood wastewater on mentioned adsorbents.the cod adsorption experiments were carried out to analyze the influence of ph, sedimentation time, contact time, initial cod concentration and adsorbent dosage. experiments show that efficiency of cod adsorption is optimum at 0.5 hour sedimentation time and 2.5 hour contact time. also results suggest relation between initial cod concentration and adsorption and concentration of adsorbent is uniformed. the higher the concentration is, the higher adsorbent dosage is required. at optimum conditions, 1 g/lit of nutshell carbon and date pit carbon can respectively remove approximately 19 & 11 percent of cod. the optimum ph for nutshell activated carbon is ph=2 and for date pit activated carbon is ph=7. at optimum conditions the maximum cod removal by nutshell activated carbon is 57% and by date pit activated carbon is 54%. other experiments on distillated water shows that nutshell activated carbon itself increase the cod of wastewater but the date pit activated carbon dose not have any effect on cod. the sem pictures of carbons (magnitude 500×) before & after adsorption process can show the operation clearly.