Study On The Removal Of Algae By Several Modified Clay Minerals

In recent years, with the rapid development of economy, surface water is seriouslypolluted and eutrophication is serious. Reason for these problems is a surge inwastewater and a lot of sewage directly discharged without treatment or treatment levelis substandard. Effective algaecide and algae control technology has importantsignificance to realize the sustainable utilization of surface water, ensure our country’swater security, maintain economic and social sustainable development. This experimentstudied the algaecide effect with a variety of clay composite PAC and chitosan modifiedclay.Experimental results show that the algae removal efficiency of clay and PACimproved significantly through composite. The mass ratio of PAC and clay hasinfluence to remove algae, and the best mass ratio to algae removal is1:5. Clay dosagealso has certain influence on algae removal, and the best dosage to algae removal is30mg/L. Under this condition, the algal removal rate is87.19%, the Chl-a removal rateis89.16%.The results of modified clay experiments to remove algae show that the algaeremoval efficiency of clay has been greatly improved by the modification of chitosan.The removal rate of algae cells and chlorophyll-a removal rate of five kinds of clay canreach90%above under the suitable ratio and dosage. Algae removal effect of modifiedclay is ideal, better than clay composite PAC.The concentration of hydrochloric acid in chitosan hydrochloride solution has greatinfluence to remove algae effect of modified clay. Algae removal effect of clay modifiedby low concentration is better than clay modified by high concentration.The mass ratio, dosage and clay types all have certain influence to remove algae.The best ratio range of clay modified by high concentration to remove algae is1:20~1:10,and the best dosage range is10mg/L~20mg/L. The best ratio range of claymodified by low concentration to remove algae is1:5~1:2,and the best dosage range is20mg/L~40mg/L. Algaecide effect of Zeolite is better than the other four kinds of clayat high concentration, Activated Clay is better than the other four kinds of clay at lowconcentration.In this laboratory conditions, Zeolite modified by low concentration has the best algaecide effect when mass ratio is1:5and dosage is30mg/L. At this condition, thealgal removal rate is95.01%, the Chl-a removal rate is95.66%.The experiment also studied the chitosan modified clay removal Micro-cystis aeruginosa, Scenedesmus quadricanda, Cyclotella meneghiniana separately. Theresults show that the effect of chitosan modified clay to remove Scene-desmus quadricanda and Microcystis aeruginosa is better, the effect of chitosanmodified clay to remove Cyclotella meneghiniana is worse.The best ratio of chitosan modified clay to remove Microcystis aeruginosa is1:5,the best ratio to remove Scenedesmus quadricanda is1:5and the best ratio to removeCyclotella meneghiniana is1:2. The best dosages respectively are30mg/L,30mg/L~40mg/L,20mg/L.In this laboratory conditions, modified Kaolin has the best algaecide effect toremove Microcystis aeruginosa when mass ratio is1:5and dosage is30mg/L. At thiscondition, the algal removal rate is92.24%, the Chl-a removal rate is95.18%. ModifiedActivated Clay has the best algaecide effect to remove Scenede-smus quadricandawhen mass ratio is1:5and dosage is30mg/L. At this condition, the algal removal rate is95.01%, the Chl-a removal rate is95.24%. Modified Sodium bentonite has the bestalgaecide effect to remove Cyclotella meneghiniana when mass ratio is1:2and dosageis20mg/L. At this condition, the algal removal rate is94.44%, the Chl-a removal rate is95.52%.