SANITARY EFFICIENCY OF ANAEROBIC FILTERS IN REMOVAL WORMS EGGS AND FAECAL COLIFORMS

Abstract

The technology of anaerobic reactors for sanitary wastewater treatment has been extensively developed in Brazil.They present several advantages, such as low construction and operating costs, and low sludge production, the anaerobic reactors are an attractive alternative to minimize problematic lack of basic sanitation in urban areas, and also of the rural areas. The anaerobic filters have been widely used in Brazil. It produces an effluent with low concentration of organic matter and solids suspended, besides conserving the nutrients, therefore, it is good for use in irrigation, but the practice must be associated with knowledge of the pathogens presence. The main objective of this study was to evaluate the efficiency of anaerobic filters in removal faecal coliforms and helminth eggs, about to that, three different systems of sewer treatment composed by anaerobic filters were analyzed. The protocol used to enumerate helminths eggs was the modified Bailenger method, (Ayres and Mara, 1996) recommended by WHO for evaluation of raw effluent and treated effluent.The membrane filtration method was utilized to determine the concentrations of faecal coliforms. The results, in a general analysis, showed that all the researched systems reached a larger removal than 93% to helminth eggs, resulting in an effluent with smaller average than 1 egg/L. One of these systems, Sistema RN, reached a larger removal than 99%, confirming the good performance of the anaerobic filters in removal helminths eggs. Even with low concentrations of eggs in the influent, the filters were able to effectively remove this parameter, ensuring a satisfactory result because it is a cheap and simple reactor of the viewpoint operational and maintenance, and has a significant health response. About faecal coliforms, it was observed for all the researched systems an effluent with 106 CFU/100mL .Even the filters not having made a good efficiency on removal of faecal coliform, the effluent of them showed low concentrations of suspended solids which is to facilitate the processes of disinfection by chlorine or UV.

Key-Words: anaerobic filters, faecal coliforms, helminth eggs, wastewater treatment.