Adsorption Capacity Comparison among Three Filter Media for Phosphorus

Experiments on adsorption for phosphorus by activated carbon, zeolite and ceramisite were conducted. The results show that adsorption capacity order of three filter media from high to low is activated carbon, zeolite and ceramisite. Influential factors which affect the adsorption capacity were surveyed. According to the analysis, the first factor is that surface isoelectric point pH of activated carbon is more than 7, but that of zeolite and ceramisite both are less than 7, therefore the activated carbon adsorbs anion phosphate easily. The second factor is related to the micropore in the adsorbent, the micropore size of activated carbon is less than 5nm, and that of zeolite is much less than that of activated carbon, meanwhile that of ceramisite is large. Micropore character is one important factor that phosphorus removal rate is much higher by activated carbon than by zeolite and ceramisite. For enhancing phosphorus removal in water purification, activated carbon filter media is the best choice among three filter material.