Srinath Patibandla

PhD Student
Project title: Systematic assessment of the formation and toxicity of by-products in the treatment of organic micro pollutants by advanced oxidation

New challenge emerging to the scientific community is Micro-pollutants. Pharmaceutical and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs) are classified as emerging micro-pollutants, which have a significant impact on environmental and public health though they are usually in a very low concentration range; from several μg L-1 to ng L-1. The major pathway for the introduction of micro-pollutants to surface water is a discharge of treated effluent from wastewater treatment plants (WWTPs) which act as primary barriers against the spread of micro-pollutants. WWTPs were based on conventional systems (chlorine, chlorine dioxide), advanced oxidation processes by means of ozonation (O3, O3/H2O2, O3/activated carbon, O3/biological treatment), adsorption/bio-adsorption on activated carbon (from lotus stalks, olive-waste cake, coal, wood, plastic waste, cork powder waste, peach stones, coconut shell, rice husk), photo-oxidation (UV, UV/H2O2, UV/K2S2O8, UV/TiO2, UV/H2O2/TiO2, UV/TiO2/ activated carbon, photo-Fenton), radiolysis (e-Beam, 60Co, 137Cs. Additives used: H2O2, SO2_3 , HCO_3 , CH3-OH, CO2_3 , or NO_3 ), and electrochemical processes (Electro-oxidation without and with active chlorine generation). The Removal efficiency of these WWTPs is ranging from 12.5 to 100% (removal yield, pharmaceutical compound mineralization, TOC removal, toxicity evolution and by-products) depending on the technology employed, physicochemical properties of micro-pollutants and experimental conditions. Advanced treatment processes such as advanced oxidation processes, activated carbon adsorption, reverse osmosis, nanofiltration and membrane bioreactors can achieve better and consistent micropollutant removal. As there is no efficient treatment method or process to remove these micropollutants, efficient techniques are needed to treat them. So the chemical we are interested in is Ferrate (VI), which exhibits high oxidation/reduction potentials, dual function as oxidant and coagulant and its promising performance in the treatment of real waste water, which was already recorded. The Removal efficiency of ferrate (VI) was pH dependent and also depends on chemical/physical properties of the pollutants. The toxicity studies conducted on ferrate (VI) treated effluent via Ames tests and zebrafish embryos tests show negative results regarding the formation of mutagenic by-products but certain recent studies showed the formation of adsorbable organic haloids (AOX) by-products. More researches are needed to classify the type and toxicity of by-products resulting from the reactions of ferrate (VI) on emerging micro-pollutants.
The objective is a systematic assessment of the formation of by-products in the treatment of organic micropollutants by advanced oxidation in order to implement ferrate (VI) into full-scale water treatment and to test toxicity using zebrafish animal model.