Vermifilter with Hot-Wall Technique in Combination with an Imhoff Tank for Wastewater Treatment in a Rural Andean Community

In the rural area, basic sanitation and water treatment is inefficient. Consequently, non treated sewage water discharges to natural water bodies occur, polluting water resources. The objective of this research was to determine of BOD₅ and thermotolerant coliforms removal from domestic sewage of a high andean rural community through a vermifilter with the hot wall technique as a combined system with the Imhoff tank. This system treated domestic sewage from the rural community of Huaylacucho in Huancavelica, Peru. The pH and the average temperature in the tributary and effluent were 6.86 and 7.09; 17.53 °C and 16.72 °C, respectively. The hot wall technique was used to improve living and development conditions of the Eisenia foetida worms in the vermifilter, by keeping the absorbed heat from daylight solar radiation and register temperatures 6 °C higher inside tan outside. In the vermifilter, was recorded on average 15.57°C temperature and 82.3% humidity. Hydraulic retention time hidráulica was 2 h and the BOD₅ removal efficiencies and thermotolerant coliforms were 50.37% and 57.53% respectively. These values did not exceed the máximum permissible limits for effluents from domestic or municipal wastewater treatment plants according to the peruvian environmental standard.