Research on model for heavy metal ions adsorption by bio-film and its affecting factors

Heavy metals are contaminations which damage to the entironment greatly. Bio-film method is an effective purify process for the removal of heavy metals from wastewater. In order to find the optimal operation condition for heavy metal ions removal by bio-film, the effects of some affecting factors included: pH value, temperature, adsorption time, quantity of bio-film, co-existed ions on the adsorption were investigated. It can be known from the results of the test that: the optimal operation condition for the adsorption of Cu2+ is: pH value is 6, temperature is about 30 ℃, adsorption time is 15 min, quantity of bio-film is 12 g, the adsorption rate can reach 65%;while, the optimal operation condition for the adsorption of Cr3+ is: pH value is 3 - 7, temperature is about 25 ℃, adsorption time is 5 min, quantity of bio-film is 10 g, the adsorption rate reachs 87%. The competitive adsorption between co-existed ions may give a great influence to Cu2+ of which the adsorption capacity is weak. There is no evidence shows that Cr3+ be affected by inhibitive action or accelerative action, thus, adsorption systems which adsorb Cu2+ only or adsorb Cr3+ only can be fitted by the classical adsorption model.