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- Ciuk Karlsson, Susanna, et al.
(författare)
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Hydraulic Properties and Reduction of COD, Phosphorus and Nitrogen in a Sand Filter used for Greywater Treatment – Simulation and Verification
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A vertical flow sand filter is a simple, effective and inexpensive system for treating greywater. The performance of sand filters treating artificial greywater was tested in the laboratory over a time period of 113 days. The filters consisted of columns (0.2 m diameter) filled with sand to a height of 0.6 m. The hydraulic properties of the filters were measured as well as the inflow and outflow concentrations of COD, BOD5, total and phosphate phosphorus and total-, ammonia- and nitrate nitrogen. To get a better quantitative understanding of the treatment processes inside the filters, the HYDRUS-CW2D computer software was used to simulate the filters. The simulation of water flow through the filter could be well fitted to the measured flow by adjusting three model parameters: the air entry value, the pore size distribution index, and the pore connectivity parameter. For the COD reduction the simulated results agreed well with experimental data after an adjustment of the microbial lysis parameters of HYDRUS-CW2D. The simulated reduction of COD was 65 %, while a 72 % reduction was measured for the filters in the lab. Simulated reduction of phosphorus in the sand filter effluent corresponded well to the measured reduction: the simulated reduction of phosphorus was 72 % while the experimental filters achieved a 79 % reduction. Also, the simulated effluent concentrations of nitrate compared quite well to the measured values. Almost no reduction (4 %) in total nitrogen took place in the experimental filters, which agreed with the simulated reduction (0 %). For the phosphorus and nitrate components in HYDRUS-CW2D, so far no changes have been made to the default parameters.
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- Dalahmeh, Sahar, et al.
(författare)
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Effects of changing hydraulic and organic loading rates on pollutant reduction in bark, charcoal and sand filters treating greywater
- 2014
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Ingår i: Journal of Environmental Management. - : Elsevier BV. - 0301-4797 .- 1095-8630. ; 132, s. 338-345
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Tidskriftsartikel (refereegranskat)abstract
- Greywater flows and concentrations vary greatly, so evaluation and prediction of the response of on-site treatment filters to variable loading regimes is challenging. The performance of 0.6 m x 0.2 m (height x diameter) filters of bark, activated charcoal and sand in reduction of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total nitrogen (Tot-N) and total phosphorus (Tot-P) under variable loading regimes was investigated and modelled. During seven runs, the filters were fed with synthetic greywater at hydraulic loading rates (HLR) of 32-128 L m-2 day-1 and organic loading rates (OLR) of 13-76 g BOD5 m-2 day-1. Based on the changes in HLR and OLR, the reduction in pollutants was modelled using multiple linear regression. The models showed that increasing the HLR from 32 to 128 L m-2 day-1 decreased COD reduction in the bark filters from 74 to 40%, but increased COD reduction in the charcoal and sand filters from 76 to 90% and 65 to 83%, respectively. Moreover, the models showed that increasing the OLR from 13 to 76 g BOD5 m-2 day -1 enhanced the pollutant reduction in all filters except for Tot-P in the bark filters, which decreased slightly from 81 to 73%. Decreasing the HLR from 128 to 32 L m-2 day-1 enhanced the pollutant reduction in all filters, but decreasing the OLR from 76 to 14 g BOD5 m-2 day-1 detached biofilm and decreased the Tot-N and Tot-P reduction in the bark and sand filters. Overall, the bark filters had the capacity to treat high OLR, while the charcoal filters had the capacity to treat high HLR and high OLR. Both bark and charcoal filters had higher capacity than sand filters in dealing with high and variable loads. Bark seems to be an attractive substitute for sand filters in settings short in water and its effluent would be valuable for irrigation, while charcoal filters should be an attractive alternative for settings both rich and short in water supply and when environmental eutrophication has to be considered.
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- Dalahmeh, Sahar, et al.
(författare)
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Quality of greywater treated in biochar filter and risk assessment of gastroenteritis due to household exposure during maintenance and irrigation
- 2016
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 121, s. 1427-1443
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Tidskriftsartikel (refereegranskat)abstract
- AimThis study evaluated treatment of greywater (GW) by a biochar filter in Jordan and assessed the annual risks of infection (Pi-annual), annual risk of disease (Pd-annual) and disease burden (in disability-adjusted life years; DALYs) of gastroenteritis caused by Salmonella spp. and rotavirus due to ingestion of GW during system maintenance and consumption of green onions irrigated with treated and nontreated GW.Methods and resultsThe biochar filter efficiently removed 93% of biochemical oxygen demand (BOD5) and 85% of solids, while removal of Escherichia coli was insignificant. Treatment of GW decreased the median Pd-annual due to ingestion of GW from 139x10(-2) to 60x10(-3) for Salmonella spp. but did not affect Pd-annual caused by rotavirus (973x10(-1) to 10). Consumption of onions irrigated with treated GW had a median Pd-annual of 125x10(-9) to 12x10(-8) for Salmonella spp. and 496x10(-4) to 437x10(-3) for rotavirus infection, which was 999 and 90% lower, respectively, than the risk when consuming onions irrigated with nontreated GW. The highest risks of gastrointestinal disease were thus associated mainly with direct ingestion of GW when maintaining the system.ConclusionsGarden produce irrigated with GW treated in biochar filter did not display intolerable risks of rotavirusbased gastroenteritis during summer season in the study area given that the produce is harvested 1 to 2days, and washed, before consumption.Significance and Impact of the StudyThis study contributes to scientific-based knowledge on the suitability of biochar filters for onsite greywater treatment and confirms the microbial safety of recycling treated greywater for garden irrigation.
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- Ddiba, Daniel, 1990-
(författare)
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Exploring the circular economy of urban organic waste in sub-Saharan Africa: opportunities and challenges
- 2020
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Globally, there is increasing awareness of the importance of applying circular economy principles to the management of organic waste streams through resource recovery. In the urban areas of sub-Saharan Africa which are going to host a significant part of population growth over the next three decades, this is especially relevant. Circular economy approaches for sanitation and waste management can provide incentives to improve infrastructure and consequently contribute resources for water, energy and food that power urban livelihoods. This thesis is situated at the intersection of the circular economy on one hand and sanitation and waste management systems on the other. It aims to contribute to knowledge about the circular economy by investigating the potential contribution of resource-oriented urban sanitation and waste management towards the implementation of a circular economy in sub-Saharan Africa and the opportunities and challenges thereof.In pursuit of the above aim, the thesis employs a mixed methods approach and is operationalized in two case study locations: Kampala (Uganda) and Naivasha (Kenya). The findings reveal the quantities of resource recovery products like biogas, compost and black soldier fly larvae that can be obtained from the organic waste streams collected in a large city, demonstrate the viability of valorizing dried faecal sludge as a solid fuel for industrial applications, and identify the factors that facilitate or impede the governance capacity to implement circular economy approaches to the management of organic waste streams in urban areas in sub-Saharan Africa. The methods used for quantifying the potential for valorizing organic waste streams and for assessing governance capacity demonstrate approaches that could be applied in other urban contexts with interest in implementing circular economy principles. The discussion highlights some key implications of these findings for sanitation and waste management practices, arguing that it is time for a shift in sub-Saharan Africa from designing sanitation and waste management systems for disposal to designing them for resource recovery.
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