Application of impregnated almond shell activated carbon by zinc and zinc sulfate for nitrate removal from water
Nitrate is a wide spread contaminant in both ground and surface water due to excessive use of nitrogenous fertilizers in agricultural activities and disposal of untreated sanitary and industrial wastes (Hudak,2000 ; Almasri and Kaluarachchi,2004). Elevated nitrate concentrations in drinking water are linked to health problems such as ethemoglobinemia in infants and stomach cancer in adults. Effluents with high concentrations of nitrate may also promote algal bloom in water reservoir (Zhi-Wei et at., 2005). The maximum contaminant level (MCL) for nitrate set by the World Health Organization (WHO) and the US Environmental Protection Agency (EPA) for drinking water are 50 and 45mg/L of NO3 respectively (USEPA, 2000; WHO, 2004). Activated carbon (AC) adsorption is one of the recommended technologies for nitrate removal from water (Mizuta et at., 2004). Mizuta conducted nitrate removal with bamboo powder charcoal as adsorbent. Activated Carbon mainly contains micropores and is efficient to remove some pollutants. In some cases, it needs mesopores to improve the adsorption velocity and mass transferring. Thus, it is necessary to increase the mesopore content in AC. One of the most effective approaches to increase mesopore and macropore volumes of AC is to catalyze the steam activation reaction of carbon by using the transition metals or rare earth metal compounds, which can promisingly promote the mesopore formation (Shen et at., 2006).