Coaction of bio-sorption and bio-filtration for the remediation of domestic and agricultural wastewater contaminated with heavy metal

Abstract

Most heavy metals are well known for their toxicity and carcinogenic properties and when disposed-off through wastewater from anthropological activities poses a serious threat to the human population and other living organisms of the receiving body. The presence of heavy metals also hampers biodegrading potential for microorganism to remediate wastewater due to theirs toxic-inhibition. In this study we combine the coaction of bio-sorption and bio-filtration with aim to improve the remediation efficiency of the Copper (Cu2+) contaminated domestic and agricultural wastewater samples in Nakhon Pathom Province, Thailand. Rice husk, agricultural waste from rice farming abundant in the area, was used as natural bio-sorbent material and tested to identify its optimum adsorption conditions. The adsorbed wastewater after sorption was fed through bio-filtration tank (sand-filled and bio-augmented with Pseudomonas stutzeri DMST 28410) and underwent bio-filtration regimes to complete the coaction remediation. Results from the present study showed rice husk grounded to the size of 106μm powder at optimal sorption conditions (pH 7, dosage 10g/L, mixing rate 150rpm., sorption time 90min., initial Cu2+ concentration 12mg/L) was effective and removed more than 40% of the metal concentration from the wastewater samples. For domestic wastewater, coaction with bio-filtration further improved the copper removal efficiency up to 96% when treated for 180min. Poultry farm wastewater yielded similar copper removal results, with sorption accounted for about 36% and coaction with bio-filtration totalling up to 97% copper removal. Wastewater parameter, Chemical Oxygen Demand (COD) from both sources after bio-sorption exhibited rises in concentration. This poses the need to further explore other pre-treatment methods for rice husk for it to fully be utilized as bio-sorbent in the removal of copper and other heavy metals from wastewater.