摘要
Cyanobacteria can produce cyanotoxins such as microcystin-LR(MC),saxitoxin(STX),and anatoxin-a(ANTX-a)which are harmful to humans and other animals.Individual removal efficiencies of STX and ANTX-a by powdered activated carbon(PAC)was investigated,aswell as when MC-LR and cyanobacteriawere present.Experimentswere conductedwith distilled water and then source water,using the PAC dosages,rapid mix/flocculation mixing intensities and contact times of two drinking water treatment plants in northeast Ohio.At pH 8 and 9,STX removal was 47%-81%in distilled water and 46%-79%in source water,whereas it was 0-28%for pH 6 in distilled water and 31%-52%in source water.When 1.6μg/L or 20μg/L MC-LR was present with STX,STX removal was increased with PAC simultaneously removing 45%-65%of the 1.6μg/L MC-LR and 25%-95%of the 20μg/L MC-LR depending on the pH.ANTX-a removal at pH 6 was 29%-37%for distilled water and 80%for source water,whereas it was 10%-26%for pH 8 in distilled water and 28%for pH 9 in source water.The presence of cyanobacteria cells decreased ANTX-a removal by at least 18%.When 20μg/L MC-LR was present with ANTX-a in source water,59%-73%ANTX-a and 48%-77%of MCLR was removed at pH 9 depending on the PAC dose.In general,a higher PAC dose led to higher cyanotoxin removals.This study also documented that multiple cyanotoxins can be effectively removed by PAC for water at pH’s between 6 and 9.
基金
This work was supported by the Ohio Department of Higher Education Harmful Algal Bloom Research Initiative(No.60075961).Funding was solely for support of conducting the research.The authorswould like to thank Jessica Glowczewski fromCity of Akron and Amy Elliot fromCity of Alliance for providing water treatment details and permission for source water collection as well as Dr.Xiaozhen Mou and Madison Summers from Kent State University for assistance in conducting the toxin measurements.
