Integrating Sanitation, Water Reuse and the Production of Food Crops – 6 Years of Experiences in Central Northern Namibia
Dr. Martin Zimmermann | ISOE - Institute for Social-Ecological Research | Germany
The goal of the CuveWaters project was to develop, implement and evaluate a sanitation system that responds to the water and sanitation challenges of peri-urban areas in central-northern Namibia. Since the start of operation in 2013 and more than three years after the plant was handed over to the city, the reuse system is still in regular use and is being well maintained.
Waste stabilisation ponds with pre-treatment provide irrigation water – a case study in Namibia.
Jochen Sinn | TU Darmstadt | Germany
This research presents the implementation of a full scale installation in Namibia. The existing waste stabilisation ponds were upgraded with an upstream anaerobic sludge blanket (UASB) reactor in comparison with a micro screen as pre-treatment to reduce COD and TSS. The results are important for fast growing communities in warm climates with the need of water reuse for irrigation.
Wastewater disinfection for agricultural reuse using solar radiation in a developing country: field observations
Prof. Dr. Rodrigo Sánchez Román | Department of Rural Engineering, Agronomic Science Faculty- São Paulo State University, Botucatu-SP | Brazil
Wastewater treatment for agricultural purposes can contribute to decrease discharge of pollutants into water bodies, reduce water uptake from the surface water and groundwater, and recycle nutrients. However, there are environmental risks associated to irrigation with wastewater, mainly due to presence of pathogenic microorganisms. Solar disinfection is a low-cost disinfection method suitable for developing country that can allow safe use of recycled wastewater for irrigation. A pilot study was performed in Botucatu, São Paulo, Brazil, to determine the feasibility of using solar radiation to disinfect reclaimed urban wastewater for agricultural reuse. The effluent from Botucatu City Wastewater Treatment Plant (WWTP) was used as supply; this wastewater passed through biological filters bed (BFB’s) before being directed to solar disinfection. The solar disinfection system (SODIS) used in the experiment has a concrete base and shape of an inverted truncated cone with the following measures: 1.00 meter for larger radius, 0.25 meters for smaller radius and 0.30 meters height. This structural form was adopted to ensure that the walls of the reactor do not produce shadows on the effluent surface for the longest time possible. The experiment was conducted at Faculty of Agronomic Sciences-UNESP, Botucatu-SP, Brazil (22º 51’ 12” S and 48º 25’ 45” W). Fixed depths of wastewater (0.10; 0.15 e 0.20 m) were tested considering different time of exposure to solar radiation from May to July 2018. After passing through the BFB’s, the wastewater presents mean values for chemical oxygen demand (COD), total suspended solids (TSS), turbidity and fecal coliform (Escherichia Coli) of 27.8 mg L-1, 8.6 mg L-1, 1.5 NTU, 2.0 x 104 MPN 100 mL-1, respectively. The three fixed wastewater depths were exposed to solar radiation for a period of 10 hours (from 08:00 a.m. to 6:00 p.m.). The collection of wastewater samples for fecal coliform (E-Coli) analysis was performed every two hours. Results of inactivation assays showed that SODIS can bring down E-coli concentrations of 104 MPN 100 mL-1 in urban wastewater to < 3 MPN 100 ml-1. E-coli was more effectively disinfected by SODIS with 0.10 m wastewater depth, exhibiting logarithms reduction values ranging between 2 log10 (99%) to 4.3 log10 (99.99%) than by the depths of wastewater of 0.15 m (1.2 log10 to 3.8 log10) and 0.20 m (1.0 log10 to 3.9 log10). Although statistical analysis did not show a significant difference (p ≤ 0.05) between the wastewater depths tested. A model was developed to estimate the remaining population of fecal coliforms in wastewater after being exposed to SODIS knowing its initial population, depth of water being treated and solar energy received. SODIS was effective in reducing mean concentration of E. coli in the three wastewater depths tested at the standard recommendation for agricultural reuse proposed by World Health Organization -WHO (≤ 1000 MPN 100 mL-1) after six hours exposures to direct sunlight. Thus, SODIS treated wastewater can successfully be used by rural communities in developing countries.
Keywords: Solar disinfection, wastewater reuse, developing country, E-coli.
On-farm wastewater treatment using biochar from local agroresidues promotes safer irrigation water for food production and enhanced crop yields in West Africa
Korbinian Kaetzl | Ruhr-Universität Bochum | Germany
Untreated wastewater (WW) is often the only available water source for West African farmers to irrigate their crops. Hence, we developed a low-cost wastewater filtration plant in Tamale, Ghana that was able to eliminate 89% COD, 92% turbidity and 62% Fe but with no significant removal of the nutrients P and N. E. coli contamination of plants irrigated with treated WW was comparable to tap water.
Remove of antibiotic-resistant bacteria from greywater
Prof. Dr. Zeev Ronen | Ben Gurion University of the Negev | Israel
Antibiotic-resistant bacteria (ARB) were monitored during the treatment of greywater (GW) in three households. Source water never contained ARB but the raw GW contained bacteria resistant to the different class of antibiotics. A recirculating vertical flow constructed wetland effectively reduce the ARB. Irrigation of soil with treated greywater did not result in accumulation of ARB in the soil.