Optimization of ceramic waste filter for bathroom greywater treatment using central composite design (CCD)

The present study aims to develop a filtration system consisting of ceramic wastes as a treatment process of bathroom greywater to reduce chemical oxygen demand (COD), Total suspended solids (TSS), Total nitrogen (TN), and turbidity. Optimization of the reduction efficiency was investigated using response surface methodology (RSM) as a function of the ceramic practical sizes (0.25–1.18 mm) and hydraulic retention time HRT (1–3 h). The functional groups on the surface of the ceramic filter media were determined using Fourier transform irradiation (FTIR), while the scanning electron microscope (SEM) was used to determine the microstructure and the surface morphology of the ceramic particles. Results revealed that the optimal reduction of COD, TSS, TN, and turbidity was influenced by active sites of the filter media (C]C, C]O, CeOeH, and OH−) and was achieved under the operating conditions of 0.25 mm of ceramic particles after 3 h of HRT, the observed and predicted reduction for COD, TSS, TN, and Turbidity were 38.8 vs. 39.8%; 58.47 vs. 59.59%; 66.66 vs. 67.32%; 88.31 vs. 89.02%, respectively. It can be concluded that the effectiveness of the ceramic filter media is a potential source for the filtration of bathroom greywater

Key factors affecting performance of biogas latrines in urban informal areas: Case of Kampala and Nairobi, East Africa

Large scale application of biogas latrine technology in developing countries faces technical, socioeconomic and financial  challenges. As a result, harnessing its full potential has not been realized. This study examined variables describing the design, construction, operation and maintenance of nineteen biogas latrines in  relation to their performance in Kampala and Nairobi, based on survey and field observations. Pre-tested questionnaires were administered to users, owners and construction  technicians/masons of the biogas latrines. Field observations were also undertaken to assess physical conditions of the biogas latrines. Principal component analysis was then used to establish correlation between variables of design, construction, operation and maintenance in relation to the performance of biogas latrines in terms of burning hours in a day. The design types of all the studied biogas latrine digesters were found to be of fixed dome. Co-digestion of human excreta and cow dung increased the number of biogas burning hours in a day from 0.5 to 1.1. The findings also show that the performance of the biogas latrines was influenced by six of the variables examined describing construction, operation and maintenance: skills of masons, use of standards in construction, training of users on operation and maintenance aspects, number of users/owners and their motivation for installation of biogas plants and physical conditions of the biogas latrines. This  implies that the use of skilled masons,  comprehensive training of users on operation and maintenance aspects and use of cosubstrates are key variables for optimal performance of biogas latrines.Key words: Biogas latrines, Kampala, Nairobi, performance

The implementation of decentralised biogas plants in Assam, NE India: the impact and effectiveness of the National Biogas and Manure Management Programme

The Indian Government’s National Biogas and Manure Management Programme (NBMMP) aims to deliver renewable energy services to households across the country by incentivising the deployment of family-sized (<6m3) anaerobic (biogas) digesters. We investigated how NBMMP policy is implemented at three levels, from government and state nodal agency, via private contractors to households. We analysed the scheme across two districts in Assam, north-east India, interviewing stakeholders in rural households, state and non-state institutions. We found a top-down, supply-side approach which enables central government to set targets and require individual states to deploy the scheme. Participation in the NBMMP was found to deliver improved energy service outcomes to a majority of households that can afford to participate, although the level of knowledge and understanding of the technology amongst users was limited. Improved training of householders, and particularly women, is needed in relation to the maintenance of digesters, feedstock suitability and the environmental and potential livelihood benefits of digestate. A policy revision which highlights the contextual and demand-side issues around adopting the technology, may deliver monetary benefits from market competition and enable development of community-focused microfinance schemes to improve the affordability of biogas systems

Effect of wastewater quality and process parameters on removal of organic matter during soil aquifertreatment

Soil Aquifer Treatment (SAT) is an the emerging managed aquifer recharge (MAR)technology, which in combination with other available wastewater treatmenttechnologies could produce effluent of acceptable quality for indirect potable reuse.This technology uses physical, chemical and biological processes in the soil matrix andaquifer for wastewater treatment. It is a low cost and appropriate option for wastewaterreclamation in developing countries that ensures sustainability of both surface water andgroundwater sources with in the context of integrated water resources management.Previous studies have been carried on removal of effluent organic matter (EfOM) andits transformations during soil aquifer treatment of conventional effluents but none hasbeen carried out for natural organic matter characterisation using non-nitrified primaryeffluent. Furthermore, detailed information on organic matter removal by SAT systemssubject to different process and hydrogeological conditions is lacking yet it is essentialfor rational design of SAT systems and to predict the degree of purification provided bySAT at various sites. Therefore, this study focussed on analysing the potential andsuitability of soil aquifer treatment (SAT) technology for removal of organic matterfrom wastewater effluents under different process conditions.The study was carried out by conducting soil column and batch tests at laboratory-scaleunder different process conditions with both primary and secondary effluent from thewastewater treatment plant of Hoek van Holland. Silica sand of size 0.8-1.25 mm wasused as a filter media. It took about 30 days to reach the steady state with respect toDOC removal. This can be attributed to the development of biofilm on the filter media.A 46 -54% DOC removal from settled primary effluent compared to 15-30% removalfrom secondary effluent was observed with the soil column tests. The DOC from nonsettledprimary effluent using batch tests was 49% and 58% under anoxic and aerobicconditions respectively. The DOC concentration of the primary effluent under aerobicconditions with both soil column and batch tests averaged 15 mg/l in both cases thoughthe biodegradation time with batch test was more than three times that with soil columntests. The effluent DOC concentration of the primary effluent increased from 15.2 mg/Lto 18.4 mg/L when the hydraulic loading rate was increased from 1.25 m/day to 2.5m/day but there was no significant change in DOC removal with secondary effluent.The drinking water DOC concentration due to NOM was 2.1 mg/L. The TOC biomassmeasurements showed a linear relationship with DOC removed for the top part of thesoil column where there was highest activity compared to the deeper part of the column.In general, it can be concluded that SAT technology has the capacity for removingorganic matter from both primary and secondary effluent. Organic matter is effectivelyremoved in the upper layer of infiltration primarily by biodegradation andcomplimented by filtration and adsorption

Sanitation in unsewered urban poor areas : technology selection, quantitative microbial risk assessment and grey water treatment; Dissertation, UNESCO-IHE Institute for Water Education, Delft.

Poor sanitation in unsewered urban slums contributes to environmental pollution and public health risks. Improvement of sanitary conditions in urban slums is hampered by limited funding, difficulty in adapting existing technologies to the local slum context and lack of a sanitation system approach to manage excreta, solid waste and grey water. A method for selection of sustainable sanitation technologies with stakeholder involvement was developed under this PhD research as an alternative to software applications. Furthermore, this study provided an insight into the genomic copy concentrations of selected waterborne viruses and the magnitude of microbial risks to human health in a typical urban slum. In addition, a prototype grey water treatment filter unit was designed and implemented at household level after the optimisation of the filtration medium and hydraulic conditions using filter columns. The high grey water return factor (85% of the water consumption) and specific pollutant loads showed that grey water generated in urban slums poses a threat to the environment and a risk to public health. In addition, the disease burden from various exposure routes in Bwaise III slum in Kampala (Uganda) was 102to 105times higher than the WHO reference level of tolerable risk of 1x10-6DALYs per person per year.This PhD study also demonstrated that grey water treatment using a two-step crushed lava rock filter unit at household level has the potential to reduce the grey water pollutant loads by 50% to 85%. However, its impact on public health and the environment needs to be assessed after a wider application of this technology within a sanitation system that incorporates sustainable management of excreta and solid waste as well