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Resource recovery through reuse of by-products of the sanitation chain presents a great potential towards ensuring universal access to safely managed sanitation. Many developing countries are faced with uncertainty over public and environmental health concerns associated with use of faecal sludge in agriculture. Due to resource constraints, limited data exists on the characteristics of faecal sludge to inform proper and safe use in agriculture. Despite predictive characterisation being demonstrated to be a resource-efficient approach to generate data in other fields, its application in agricultural resource recovery from faecal sludge is lacking in the literature. This paper explored predictive modelling as a less resource-intensive approach for characterisation of nutrients and pathogens in faecal sludge. Specifically, it investigated the extent to which gravimetric parameters could predict nutrients and pathogens in pit latrine sludge from informal settlements in the cities of Malawi. The study explored predictive models to estimate total ammoniacal nitrogen (TAN), total phosphorus (TP), E.coli and helminth eggs from gravimetric parameters (total solids [TS] and total volatile solids [TVS]) in pit latrine sludge. The models developed in the study allow substantially reliable estimation of TAN (R2pred = 75.4%) and TP (R2pred = 78.2%), they also provide moderately reliable predictions for E.coli (R2pred = 69.1%) and helminth eggs (R2pred = 74.3%) from total solids. Since total solids are easy and inexpensive to measure, the models present an option that can reduce resource requirement for characterisation of pit latrine sludge for informed decision-making when using pit latrine sludge in agriculture. In the absence of data on faecal sludge characteristics at the national level, the models provide a starting point for estimation of pathogens and nutrients in sludge for agricultural use. However, stepwise refinement of the models needs to be done through their validation for different types of sludge and inclusion of spatially available demographic, technical and environmental (SPA-DET) data.

Many developing countries lack the infrastructure needed for the treatment of fecal sludge. One limitation in implementing available treatment options is the limited availability of land in the urban areas of these countries. This paper investigated the application of process intensification as a way of reducing the land area required to dewater and sanitize pit latrine sludge from informal settlements in Blantyre City, Malawi. The intensification of the sludge treatment process was achieved by enhancing dewatering through the application of additives and by combining the dewatering and sanitization stages. Nine combinations of sludge, lime and rice husk dosages, in addition to a control, were simultaneously loaded on unplanted drying bed units to dewater for 29 days. The study found a significant reduction of 21% to 73% in the land area required to dewater and sanitize pit latrine sludge. From the study, process intensification was shown to have the potential to significantly reduce the land area required to dewater and sanitize pit latrine sludge from informal settlements in Malawi cities. This makes it an option that can be implemented close to informal settlements, despite land limitation in these areas.

The limited availability of data on faecal sludge characteristics remains one of the major challenges faced by the developing countries in proper management of faecal sludge. Taking into account the limited financial resources and expertise, there is a need to come up with less resource intensive approaches for faecal sludge characterisation in these resource-constrained developing countries. Despite being used substantially in wastewater, there is a lack of evidence pointing towards the predictive modelling being used as a tool for cost-effective characterisation of faecal sludge. In this study, first order multiple linear regression models are developed as a cost-effective approach for accurate predictions of organics (biochemical oxygen demand and chemical oxygen demand) in pit latrine sludge. The predictors explored during the modelling include pH, electrical conductivity, total solids, total volatile solids, fixed solids and moisture content. The models are built using the data collected from a total of 80 latrines from informal settlements in four cities in Malawi. The results for the models show that it is possible to reliably predict the chemical oxygen demand and biochemical oxygen demand in pit latrine sludge using the electrical conductivity and total solids, the determination of which requires low levels of resources and expertise.

Most developing countries use existing knowledge and infrastructure for wastewater in the treatment, reuse and disposal of faecal sludge. There is need to have a clear picture of the risk faecal sludge poses in relation to wastewater if effective treatment, disposal and reuse systems are to be implemented. Little work has been done to quantify the risk faecal sludge poses in relation to wastewater in a localized setting. This study quantifies the comparative risk of faecal sludge from pit latrines in unplanned settlements in Mzuzu City and wastewater. A total 80 sludge samples were obtained from 20 pit latrines in five unplanned settlement Laboratory characterisation was performed for Organics (chemical oxygen demand and biochemical oxygen demand), nutrients (total ammonia nitrogen and total phosphorus) and pathogens (Escherichia coli and helminth eggs) were determined through laboratory analyses. Documentation review was used to get wastewater characteristics. The study found a higher risk (comparative risk >1; p < 0.0001) for organics and nutrients in pit latrine sludge as compared to wastewater. Pit latrine sludge was found not to pose significantly higher public health risk from both E. coli (comparative risk

A review of Japan’s fungicide usage from the 1960s to recent times was conducted using data from the National Institute of Environmental Studies, Japan. A total of 16 commonly used fungicides were assessed and these are: captan, chlorothalonil, fenarimol, ferbam, fosetyl-Al, iprodione, isoprothiolane, mancozeb, mepronil, metalaxyl, myclobutanil, pencycuron, thiophanate-methyl, tolclofos-methyl, triadimefon and trifloxystrobin. The assessment revealed that the most used fungicide within the period (1962–2014) was chlorothalonil with a maximum usage amount of 1795 tons/year. The least used was found to be myclobutanil with a maximum usage amount of 8 tons/year within the same reporting period. Generally, the usage of most of the fungicides peaked between the 1980s to early 2000s. For most of these fungicides, their usage amounts have decreased in recent times. However, the continuous usage of these fungicides has a potential to cause problems in the environment ranging from mere irritations to being very toxic to human beings and organisms.

A study was carried out to assess levels of contamination of aflatoxins and fumonisins (B1 + B2) in maize produced, stored and consumed in rural households in Malawi. A total of 9 districts were selected across the country representing 3 districts from each of the Northern, Central and Southern regions respectively. Households were selected at random in each district where 10 maize samples were collected for laboratory analysis. Aflatoxins and fumonisins were analyzed using a single step lateral flow immunochromatographic assay based on a competitive immunoassay format. The detection limit for aflatoxins was 2 μg/kg with a quantitation range of 2–150 μg/kg and that for fumonisins was 1 mg/kg with a quantitation range of 1–7 mg/kg. It was found that samples in the Southern region were highly contaminated, with the Chikhwawa district having high levels of both aflatoxins and fumonisins in maize. The Northern region had the least contamination. The maximum detected amount of aflatoxins was 140 μg/kg. The maximum detected amounts of fumonisins was 7 mg/kg. About 20% of maize samples exceeded the tolerable maximum limit for aflatoxins in Malawi. Aflatoxins and fumonisins were found to co-occur with contamination levels exceeding 100 μg/kg for both aflatoxins and fumonisins. Keywords: Mycotoxins, Aflatoxin, Fumonisins, Malawi

This review paper covers the issues of pit latrine emptying national policies and regulations with a focus on Malawi and Zambia. With 2.4 billion people worldwide still lacking improved sanitation facilities, developing countries need to look at policy, regulation and practice for household sanitation service provision with a new lens. What happens “next,” when improved sanitation facilities eventually become full? An emphasis on faecal sludge management has multiplied this important issue in the past few years. The authors compare the pit latrine emptying situation in Malawi and Zambia with a focus on status, challenges and opportunities. To build this comparison, a desk review of national policies, local regulations and peer-reviewed journal papers was conducted. The paper concludes that existing national policies and regulations taking faecal sludge management into account are weak and have wide gaps in the two study countries. For the future, it is recommended, first, that household pit latrine emptying should be seen as an opportunity to address national sanitation gaps and, second, national policies and regulations need to be evaluated and updated. Key words: Faecal sludge management, pit latrine, policy, private sector, sanitation.

In this research, three faecal sludge sanitizing methods—lactic acid fermentation, urea treatment and lime treatment—were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH &gt, 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m3 of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment.

One of the parameters that impact on fluoride sorption capacities of materials in water defluoridation is initial concentration. Water from various sources will have different fluoride concentrations; as such the employment of a particular media in defluoridation requires information on how the media will perform in different concentrations. Consequently, research was carried out to determine how initial fluoride concentrations in raw water affect capacity in defluoridation with bauxite, gypsum, magnesite and their composite, and to investigate the possibility of predicting loading capacity of their composite filter through initial fluoride concentration to optimize their application in defluoridation. The results showed that sorption capacities increased with increase in initial concentrations. However, higher starting concentrations resulted in larger residual fluoride concentrations; as such the benefit of large sorption capacities obtained was overshadowed. Polynomial relations of capacity ( C s , mg/g) and initial concentration ( C o , mg/l), were obtained for bauxite and gypsum. Magnesite obtained a logarithmic relation for C s and C o . A power relation was obtained between C s and C o for their composite, C s = 0.0328 C 1.2016 0 . Approximation of capacities of this composite from initial fluoride concentrations was feasible. Water defluoridation has become important as a result of dental and skeletal fluorosis.

Research was carried out at Ngurdoto research station in Tanzania to ascertain the potential development of a water filter made of bauxite, gypsum and magnesite in an attempt to enhance the availability of low-fluoride water. The materials were sourced within Tanzania. The X-Ray fluorescence technique showed that the major components of the materials were: bauxite: Al2O3 (30.33%), SiO2 (15.0%) and Fe2O3 (14.3%); gypsum: CaO (28.09%), SO3 (34.96%), and SiO2 (9.01%); and magnesite: MgO (34.57%) and SiO2(19.3%). The materials were calcined at 350, 400, 450 and 500°C. The activated materials were then mixed in mass ratios of 1:2:3, 1:3:2, 2:1:3, 2:3:1, 3:1:2 and 3:2:1 (bauxite: gypsum: magnesite). One gram of each composite was employed in the batch defluoridation of 1 L of water with fluoride concentration of 12.62 mg/L. The highest defluoridation capacity, 11.89 mg F-/g, was obtained with the 3:2:1 to 500°C composite. The quality of the treated water fell short of WHO standards on sulphates and iron but residual concentrations of Cl-, Al3+, Ca2+, Mg2+, Fe2+ were within the prescribed limits. Sorption behavior followed strongly to Langmuir isotherm, except for the 450°C calcined samples for which the Temkin isotherm behavior was pronounced. Despite the limitations of high residual sulphates and iron, a composite filter of bauxite, gypsum and magnesite was shown to be workable. Key words: Defluoridation, bauxite, gypsum, magnesite, composite, calcine, isotherm.

Breakthrough characteristics, kinetics, and dose-effect in defluoridation with bauxite, gypsum, magnesite, and their composites were determined. The aim was to identify optimum filter and configuration viable for groundwater defluoridation. Bed depth service time (BDST) design model and empty bed residence time (EBRT) optimization model were employed to characterize breakthrough. Higher doses obtained lower loading capacities but higher sorption percentages and breakthrough times. Breakthrough times obtained were 50 400, 32 400, 25 200, and 19 800 s for 150, 120, 75, and 45 g, respectively. The equation ħ = 1.0 × 10−4 δ2 −0.022 δ + 1.5053 defined the operating line with ħ, adsorbent exhaustion rate, in g L−1 and δ, EBRT, in seconds. A critical bed depth (Zo) of 6.56 cm was obtained. Second order kinetic rate constants were 0.73, 1.17, and 1.81 g mg−1 s−1 for magnesite, gypsum, and bauxite, respectively. The composite, gypsum and bauxite decreased water pH but magnesite increased pH in water defluoridation. Experimental data did not fit the two-parameter logistics model; model values were significantly different from experimental values. Optimum defluoridation characteristics were obtained in fixed bed. Despite high residual sulphates and apparent color, fixed-bed defluoridation with raw composites of these materials, treated in this manner, is viable.

Reaction kinetics and breakthrough characteristics in water defluoridation were studied through experiments with 200 °C-calcined bauxite, gypsum and magnesite and their composite filter. The aim was to determine defluoridation potential of a composite filter of the three locally sourced natural materials in contribution towards fluorosis mitigation. The materials were crushed and sieved to particle sizes of 1.2–1.4 mm diameter, and then heat-treated at 200 °C for 2 h. Their defluoridation capacities and reaction kinetics were determined in batch. A composite was then prepared in the ratio of the loading capacities. Breakthrough characteristics were experimented on in fixed bed through bed depth service time (BDST) design model, empty bed residence time (EBRT) optimisation model and the two parameter-logistics (2-PL) model. Mean loading capacities of 5.6, 3.4 and 1.7 mg F − /g were obtained for bauxite, gypsum and magnesite, respectively. Loading capacities decreased, while sorption percentages increased, with increase in dose level. Second order kinetics observed had rate constants 4.07 × 10 −2 , 1.87 × 10 −2 , 1.59 × 10 −2 g mg −1 min −1 for bauxite, gypsum and magnesite, respectively. Composites, bauxite and gypsum decreased, while magnesite increased water pH. Time at 50% breakthrough ( τ ) obtained experimentally compared well with τ obtained through the two-parameter logistics model indicating good fitness of data to the model. Greater doses obtained higher breakthrough times that were, 120, 210, 255 and 360 min for 45, 75, 120 and 150 g, respectively. Critical bed depth ( Z o ), 7.71 cm and an operating line, ℏ = 4 × 10 −4 δ − 0.0757 δ + 4.86 (ℏ = adsorbent exhaustion rate, δ = EBRT) were obtained. The water quality was within recommended quality limits for pH, apparent colour, hardness, and residual concentrations of SO 4 2− , Cl − , Fe 2+ , and Al 3+ in fixed bed. The research showed that a composite filter of the three materials, prepared in the ratio of their loading capacities and calcined at 200 °C, is a potential defluoridating filter in fixed bed configuration.

Free fluoride levels above the WHO guideline maximum value of 1.5 mg/l have been reported in several parts of Malawi. Dental fluorosis has also been observed in the same areas such that search for local defluoridation techniques has become important in the country. The present research intended to determine the potential of using Malawi gypsum in defluoridation, identify the best pre-treatment of the gypsum and optimum conditions under which effective water defluoridation with the gypsum may be obtained. Laboratory experiments were carried out to explore defluoridation of drinking water using locally sourced gypsum and gypsum calcined at high temperatures. A 400 °C calcined phase of gypsum gave the highest defluoridation capacity of 67.80% compared to raw (uncalcined) gypsum, 200, 300 and 500 °C calcined phases. Powder X-ray diffraction (PXRD) pattern of the 400 °C phase revealed existence of less crystalline CaSO 4 that was thought to be responsible for such relatively high defluoridation capacity. The dependence of the fluoride removal by the 400 °C calcined phase on other drinking water quality parameters was assessed by simple correlation analysis. Reaction kinetics and mechanisms of fluoride removal by the materials were also investigated. It was found that ion exchange was the dominant mechanism through which fluoride was removed from water by the materials.

Ground water is main source of water supply in most rural communities in Africa. It has good microbiological and biological properties in general as such requires minimal treatment. Unfortunately groundwater is sometimes contaminated with naturally occurring chemicals. One such naturally occurring toxicant is fluoride. In some parts of Africa ground water contains high fluoride levels beyond the recommended World Health Organisation upper limit of 1.5 mg/l. It is reported that the East African Rift Valley is a high fluoride area. This region extends from Jordan valley down through Sudan, Ethiopia, Uganda, Kenya and Tanzania. High fluoride levels have also been reported in Malawi and The Republic of South Africa. In Kenya high fluoride levels in ground water beyond 5 mg/l and beyond 8 mg/l were reported in 20% and 30% respectively of 1000 samples taken nationally. A survey of fluoride in ground water in Tanzania showed that 30% of the waters used for drinking exceeded 1.5 mg/l fluoride. In Malawi and the Republic of South Africa fluoride levels beyond 1.5 mg/l and occurrence of dental fluorosis have also been reported. Proxy indicators of high fluoride levels in ground water are high pH, pH beyond 7, and high sodium and bicarbonate concentrations in the water. High fluoride waters often have low calcium and magnesium concentrations as such are fairly soft. There are some exceptions of fluoride occurrence that may not adhere to these proxy indicators.

Water defluoridation in a fixed bed column may be optimized through choice of flow rate. This, however, affects breakthrough characteristics. In any fixed bed system an understanding of flow rate and breakthrough interactions is therefore important to guide choice of design velocity. Consequently interactions between flow rate and break through characteristics were determined in a fixed bed column in defluoridation with a composite filter of bauxite, gypsum and magnesite. This was an attempt to optimize defluoridation with the three materials. Lower flow rates obtained longer service times but higher residual concentrations of sulphates and chlorides. Higher flow rates registered lower residual sulphate and chloride concentrations but obtained lower service times. There were no significant differences in residual concentrations of aluminium, iron, calcium and magnesium among the different flow rate regimes. Adsorbent exhaustion rates and critical bed depths increased with increase in flow rates, indicating that lower flow rates offered better technical system performance. Critical bed depths ranged from 5.23 to 10.89 Cm for flow rate range of 0.68 to 1.25 ml/s. operating lines were polynomic with generic form 3 2

Research on water defluoridation with composite filters of bauxite, gypsum and magnesite was carried out at Ngurdoto Research Station to determine capacity, nature of fluoride-sorbent interaction and changes in water quality. The objective was to identify an optimum composite filter that would not alter the water quality beyond World Health Organisation recommendations. The three materials were characterized through X-Ray Fluorescence. The major components were Al2O3 (30.33%) for bauxite, CaO (28.09%) for gypsum and MgO (34.57%) for magnesite. The materials were calcined at temperatures of 150, 200, 250 and 300 o

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