Anaerobic treatment of domestic wastewater in subtropical regions

摘要: In this thesis, the application of upflow anaerobic sludge bed (UASB) reactors for treatment low-strength domestic sewage was studied city Salta , in northwestern Argentina . The climate region can be defined as subtropical with a dry season. Mean ambient temperature is 16.5oC. during experiments 23.0°C (monthly minimum: 17.2°C; daily 12.6°C). A literature review on use performed, and brief description laboratory, pilot-scale, full-scale applications from all over world presented. Experiments were performed two pilot plants especially built thesis. first plant UASB reactor installed after conventional sedimentation tank (settler). second two-stage system posttreatment five waste stabilization ponds (WSP) series. plant, chemical oxygen demand (COD) removal efficiencies up to 84% total COD 92% suspended achieved at mean hydraulic retention time (HRT) 2 h settler 5.6 reactor, equivalent an velocity (V ) 0.71 m/h. granular developed probably due low concentration solids (SS) influent adequate combination HRT V Some granules surprisingly big (up 5 cm diameter). highly robust efficient, it consistently delivered final effluent compliance discharge standards SS, produced small amount well-stabilized sludge. two-step 89% obtained HRTs 6.4 + = 0.62 0.70 m/h), 83 36% steps, respectively. similar that plant. performance not affected coldest period year, which usually lasts about three months. showed good stability, summer time, could directly disposed without further treatment. After posttreatment, also complied pathogenic microorganisms. It concluded single-stage followed by series WSP very reliable, compact, simple raw regions like Finally, comparative assessment sustainability technological options terms technical, environmental, social, economic criteria indicators. preliminary found that, under local conditions, more sustainable than (a) aerobic high-rate based trickling filters, (b) WSP. method used (a multi-criteria weighted-scale matrix) perform sensitive enough detect differences between compared. representative panel stakeholders must actual transparent participatory way before any concrete policy decision taken. plead thesis development will only through fully democratic decision-making go beyond political motivations may able solve environmental problems social injustices.