Variability of faecal sludge characteristics and its implication for dewaterability across different on-site sanitation containments in unplanned settlements in Dar es Salaam, Tanzania

Doglas, Benjamin; Kimwaga, Richard; Mayo, Aloyce W.

doi:10.2166/wpt.2021.052

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…The Total solids (TS) and the volatiles solids (VS) significantly increased in the sludge tank and the dry bed, respectively (12.66 ± 0.48% to 53.40±8.82% and 11.22±0.09% to 29.79±9.94%). This increase in the values of TS and VS after dewatering agrees with a study by Douglas et al (2021), where there was a significant increase of TS of sludge samples from pit latrine during the dry season. In addition, al-Malack et al ( 2008) also recorded an increase in the VS from 51, 51 and 53 per cent to 65, 62 and 66 per cent at the sludge tank, lagoons and dry beds respectively.…”

Section: Journal Of Environmental Sciences and Technologysupporting

confidence: 91%

The physico-chemical properties of sewage sludge processed for agricultural use from the Nyeri-Kangemi wastewater treatment plant, Nyeri county, Kenya

Muia

2022

JEST

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This study was conducted to assess the physico-chemical properties and changes that occur in the composting process between raw sewage sludge inflow at the sludge tank and the composted end product in the dry beds used for agricultural application at the Nyeri-Kangemi wastewater treatment plant in Nyeri County, Kenya. Sludge samples were collected between June and October in different stages of the sludge treatment process; the sludge tank received from the primary and secondary wastewater treatment processes and the composted sludge from the dry beds. Results showed the final composted dry sludge had a pH ranging from 5.53 to 6.52. The mean values were; EC was 3.77 ± 0.05 mS/cm, TOC of 2.03 ± 0.05 per cent, ON of 0.19 ± 0.01 per cent, TOP 88 ± 1.6 mg/L, Temperature 21.03 ± 0.06 °C, particle density of 2.30 ± 0.02 g/cm3, Bulk density of 0.24 ± 0.02 g/cm3, 90.7 ± 0.01 per cent pore space, moisture content of 11.3 ± 0.70 per cent, TS of 53.40 ± 8.82 per cent and VS of 29.79 ± 9.94 per cent. The concentrations of Fe, Ca, Mg, Mn, K, Na, Zn and Cu were 1896.15 ± 106.2 mg/l, 266.42 ± 27.55 mg/l, 190.52 ± 4.82 mg/l, 139.3 ± 0.29 mg/l, 114.38 ± 4.81mg/l, 84.61 ± 0.71 mg/l, 39.18 ± 0.36 mg/l and 5.65 ± 0.12 mg/l respectively. This study recommends the need to do more research on how to improve and stabilise the physico-chemical parameters in the sludge treatment before agricultural use.

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Section: Journal Of Environmental Sciences and Technologysupporting

confidence: 91%

The physico-chemical properties of sewage sludge processed for agricultural use from the Nyeri-Kangemi wastewater treatment plant, Nyeri county, Kenya

Muia

2022

JEST

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“…Characteristics of fecal sludge in this study are presented in Figure 3. The characterization results (i.e., pH, EC, VS, TS, COD) did not follow a normal distribution (Shapiro-Wilk test < 0.05), as is commonly observed with characteristics of fecal sludge (Gold et al, 2018;Englund et al, 2020;Doglas et al, 2021;Strande et al, 2021). Hence, medians are reported as more representative, or when reporting mean and standard deviation, we also report how far apart the mean and median are.…”

Section: Qualities: Comparison Of Fecal Sludge Characteristics In Sev...mentioning

confidence: 94%

Quantities and qualities of fecal sludge: Experiences from field implementation with a Volaser in 7 countries during a pandemic

et al. 2023

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Reasonable estimates for quantities and qualities (Q&Q) of fecal sludge that accumulate in onsite sanitation containments are fundamental for the design of appropriate management and treatment solutions, from community to city-scale. There are increasing attempts to improve Q&Q estimates, but current approaches are still at a conceptual level, and are not yet standardized with confirmed statistical relationships. To reach this level, we will need consistent approaches for planning, measuring, and global collaborations. Hence, the objectives of this study were: (1) to assess and compare Q&Q of fecal sludge from seven cities and communities, and explore statistical relationships that could be used to increase accuracy of Q&Q estimations; (2) to test and launch the Volaser device for measuring in situ volumes of fecal sludge; and (3) to capture lessons learned from field implementation with collaborators in seven countries during a global pandemic when no international travel was possible. The study took place in Ghana, India, Lebanon, Kenya, Sierra Leone, Uganda, and Zambia during the COVID-19 pandemic. Q&Qs were measured in 204 containments with a Volaser, laboratory analysis, and questionnaire. Results indicate that there are differences in Total Solids (TS) and Chemical Oxygen Demand (COD) in fecal sludge based on containment type, toilet type, source, and whether there is a water connection on the premises. Based on the results of this study, together with previously published open-source data, an empirical relationship for Volatile Solids (VS) and TS of 0.49 (R2 = 0.88) was established using 1,206 data points. For COD/TS, no significant relationship was observed. Developing such empirical relationships will be useful for planning and modeling approaches. An external evaluation was conducted to evaluate overall project management, Volaser technology transfer, and effects of collaborating during the COVID-19 pandemic. Success factors for collaborating with new and existing partners without face-to-face meetings included laboratory capacity and experience with analytical methods, study objectives that were relevant for the partner and locality, and a strong quality assurance plan to ensure comparability of results. The lessons learned can be taken forward as ways to reduce carbon footprint, and contribute to resilient, inclusive development research projects.

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“…Previous studies have found that concentrations of heavy metals in faecal sludge vary based on season and source. For example, a study in Dar es Salaam, Tanzania, found a significant difference between the dry and rainy seasons in conductivity value and total solids concentration in pit latrine sludge (Doglas et al, 2021). Yet, it may be difficult to extrapolate data from African studies to the Asian context.…”

Section: Introductionmentioning

confidence: 99%

Estimating qualities and quantities of faecal sludge to determine resource recovery potential : A case study in Phnom Penh, Cambodia

Eliyan

2023

Acta Universitatis Agriculturae Sueciae

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A paradigm shift to convert faecal sludge into resources could minimise environmental pollution and public health risks in cities in low- and middle-income countries (LMIC). To support faecal sludge management planning at city scale, this thesis investigated resource recovery potential from faecal sludge, using Phnom Penh as a case and focusing on waterborne systems. Methods used were faecal sludge sampling and analysis, stakeholder interviews, observations and multi-criteria assessment. Resource recovery potential from faecal sludge in Phnom Penh was found to be limited. Many quality parameters in faecal sludge were low compared with previously reported values, owing to dilution effects of high prevalence of waterborne toilets, addition of water during emptying events, mixed wastewater capture by containment units and connection of containment units to the urban drainage network. Concentrations of two heavy metals (mercury and zinc) exceeded the limits in the Cambodia standard for organic fertiliser and Swedish standard for compost. The highly diluted nutrient content and relatively high heavy metal contamination in faecal sludge limit its reuse potential. However, reuse of sludge could capture around 65 tons of total nitrogen and 13 tons of total phosphorus annually instead of allowing these nutrients to enter natural wetlands. Three options to tackle the current challenges in faecal sludge management in Phnom Penh were identified: (i) short-term: use of treated faecal sludge as soil conditioner for public green space; (ii) medium-term: upstream source control to prevent contamination of sludge; (iii) long-term: source separation. Solar drying and vermicomposting are appropriate technologies for short-term solutions and co-composting, larval composting and vermicomposting for medium-term solutions, after implementing upstream source controls. For long-term solutions, extensive research on appropriate technologies is needed. Overall, the best option will depend on relative weighs of sustainability criteria and trade-offs for sector stakeholders. These findings can assist sector stakeholders in Phnom Penh and other LMIC cities with similar sanitation systems in improving faecal sludge management.

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Variability of faecal sludge characteristics and its implication for dewaterability across different on-site sanitation containments in unplanned settlements in Dar es Salaam, Tanzania

Cited by 6 publications

References 18 publications

The physico-chemical properties of sewage sludge processed for agricultural use from the Nyeri-Kangemi wastewater treatment plant, Nyeri county, Kenya

The physico-chemical properties of sewage sludge processed for agricultural use from the Nyeri-Kangemi wastewater treatment plant, Nyeri county, Kenya

Quantities and qualities of fecal sludge: Experiences from field implementation with a Volaser in 7 countries during a pandemic

Estimating qualities and quantities of faecal sludge to determine resource recovery potential : A case study in Phnom Penh, Cambodia

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