Effective removal of Helminths Ova from wastewater and its inactivation from sewage sludge using thermophilic anaerobic digestion

Abstract

Treated wastewater became a sustainable alternative to reuse for irrigation and household purpose. The presence of pathogens, i.e., viable Helminths Ova (viable HO) might become a serious health issue for the safe use of the treated wastewater. HO represents an important challenge to environmental engineering as they are among the most difficult biological parasites to remove from wastewater and inactivate in sludge. In light of this, the current study thoroughly investigated the presence and destruction of active HO in field full-scale municipal wastewater using pressurized sand filtration (PSF) and lab-scale thermophilic anaerobic digestion (TAD) process. The presence of HO as 16 Ova/L in wastewater and 35 Ova/L in sewage sludge were identified. Upon further species identification, the major species of HO, such as, Ascaris (70.83 %), Trichuris (12.50 %), Hymenolepis (12.50 %), and Toxocara (4.17 %) were detected. The maximum HO removal of 100 % and TSS removal of 97.14 % from the wastewater were noticed with the use of cost-effective PSF technique. Moreover, a significant inactivation efficiency of 51.43 % was observed from sewage sludge using TAD over a period of 60 days. The maximum COD and TSS removal of 34 % and 60.35 %, respectively, was noticed in the TAD process. The study showed that TAD could be an effective pre-treatment step for the destruction of viable HO. The PSF and TAD combined technology could contribute to municipal wastewater treatment in a sustainable way to improve environmental protection, resource recovery and public health protection.