Investigation on the Pollution of Cryptosporidiumparvum and Giardia lamblia Stiles in Drinking Water and Wastewater in Shenzhen

Objective To investigate the pollution of parasitic protozoa in drinking water and wastewater in Shenzhen in or-der to present evidence to establish the national hygienic standard for parasitic protozoa in drinking water.Methods Water samples of resource water,fin ished wa ter from3water plants,and post-treated wastewater samples from3wastewater treatment plants in Shenzhen city were collected.Para sitic pro tozoa Giardia lamblia Stiles and Cryptosporidiumparvum were detected by following steps:filtering,washing,magnetic isolation and staining.Results Giardia lamblia Stiles and Cryptosporidiumparvum were not found in samples from raw water and finished water,while they were found in post-treated wastewater samples from2wastewater treatment plants.Conclusion The results indicated that the prob lem of Giardia lamblia Stiles and Cryptosporidi -umparvum pollu tion in the water supplying systems didnt exist at present,but Giardia lamblia Stiles and Cryptosporidi umparvum in the post-treated wastewater were the potential pollution source to surface water.