Estabilização e higienização de fezes humanas através de compostagem em regime de batelada

Abstract

Ecological Sanitation (Ecosan) refers to a system of wastewater management that focuses on recycling water and nutrients back to their original source. The human faeces from urine segregation contain valuable qualities to soil improvement, however the main concern of this recycling process is the presence of a potential enteric pathogen found in faeces. For this reason, composting is the most common treatment used to disinfect faeces and is used as a soil conditioner. In this prospective, the objective of this paper is to study the physical chemistry and biological characteristics of human faeces. Furthermore, this paper has examined the production and treatment of composting and look into potential technological solutions of ecosanitation in cities. This research has presented the methodology in two phases: I. Faeces qualitative and quantitative characterization and II. Composting of faeces in three different matrices with sawdust. The results have demonstrated a fecal production of 130 g/person/day with a comparable excretion average between men and women. The results of the physical chemistry characterization demonstrated that the average content of moisture was 75%, 85% of total solids and averages for nutrients such as nitrogen and phosphorus were 13 and 3,2 g/kg of faeces respectively. The microbiologic test results showed a concentration of total coliforms, thermotolerants and Escherichia coli at, 107 , 106 and 105 NMP/g respectively. Regarding the composting process, the temperatures were over 50°C and E.coli reduction was not recorded at detectable levels. The faeces and sawdust proportion of 30% proved to be the best process performance, when kept in thermophilic temperature for over 16 days and disinfected for 7 days at a temperature greater than 50°C. Furthermore, these results indicated the best reduction in total and volatile solid content, 64% and up to 76%, respectively. Finally the human faeces are a nutrient source of N, P and K and hence for this reason, demonstrate a potential to be reusable through sustainable treatment as opposed to the conventional sanitation system currently under use. Composting with sawdust as a raw material establishes a viable alternative to the treatment and compost stabilization.