Evaluation of the Green Oxidant Ferrate for Wastewater Reuse for Wetland Restoration

Chlorination has been used effectively for disinfection of waters since the early 1900's, and as a result, waterborne diseases and mortality have been drastically reduced. However, it was discovered in the 1970's that chlorination of wastewaters resulted in carcinogenic byproducts such as trihalomethanes (THMs) and haloacetic acids (HAAs), while also found to be largely ineffective for disinfecting organisms such as Giardia, Cryptosporidium, and aerobic spore forming bacteria. More recently, ferrate (Iron VI, as FeO42-) has gained momentum in being a viable disinfectant for water treatment since it can be economically produced from commercially available feedstocks on-site. This research will elucidate the efficacy of ferrate for disinfection by determining minimal contact time and dose for municipal wastewater effluent by assaying changes in fecal coliform, E. coli, enterococci, and coliphages.An important point of the ferrate technology is it can be integrated in existing chlorination hypochlorite systems. In fact, the ORP monitoring system use in chlorination can be refined to utilize ferrate instead of hypochlorite. The specific advantages of ferrate over chlorine are:Production of a pathogen free effluent with respect to E. coli, enterococci, bacterial phages, endospores and protozoan oocysts. Chlorine has a limited capacity to disinfect these microbes.Current disinfection processes tend to produce potential problem by-products while ferrate will not produce these chlorinated by-products.This paper evaluates the potential use for wastewater disinfection in the scope of sustainable water reuse. Current research is evaluating the efficacy of discharging ferrate-treated wastewater to Louisiana's wetlands to help with coastal restoration.