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This paper explored people’s perceptions on the use of human excreta for biogas generation in Ghana using the theory of planned behaviour (TPB). It sought to assess the effect of attitude, subjective norms and perceived behavioural control on people’s behavioural intention to use human excreta (HEx) for biogas. Data collection was by questionnaire designed with the TPB constructs and other demographic information, and the analysis was done by structural equation modelling (SEM). The analysis produced two structural models: the standard TPB model and the adjusted model. Based on SEM, this study revealed that the adjusted model provides a useful and effective framework for analysing the interrelationships between socio-demographic variables and the standard TPB constructs than the standard TPB. Therefore, the results show that the effect of attitude, subjective norms and perceived behavioural control are all significant and positive. Though all the constructs were significant and positive, participants showed low perceived behavioural control or they perceive low ability of using HEx for biogas. Results revealed an adequate fit for people’s behavioural intentions to use HEx for biogas. The adjusted model, generated by the inclusion of gender and education into the TPB model, provided a useful and effective framework for the interrelationships between socio-demographic variables and the TPB constructs than the standard TPB. Attitudes, subjective norms and perceived behavioural control significantly influenced intentions to use HEx for biogas. Though perceived behavioural control showed low controllability, subjective norm was a major factor with religion being key on intentions to use HEx for biogas generation. Gender and education had no direct significant influence on intentions, but their effects were mediated through the TPB factors. It was further revealed that knowledge on the benefits of biogas as well as the perceived effect of using human excreta was strong and positive. Interventions aimed at promoting the use of HEx for biogas should address low controllability and that should include government subsidy and financial support as well as education to address stigma and HEx knowledge. The intervention should also bring on board important persons such as religious leaders and persons from relevant institutions to lead more open discussions on HEx use for biogas.

During the past three decades, constructed wetlands have become an integral part of the suite of technologies for removing domestic and industrial wastewater contaminants. The use of constructed wetlands has disproportionately focused on domestic and agricultural wastewaters and storm water runoff and less on oil and gas-related produced water. In this context, the cumulative effect of environmental factors on the treatment/removal efficiency of contaminants in produced water is underserved by research. Therefore, this study assessed the effect of environmental factors (temperature, dissolved oxygen, oxidation–reduction potential, and pH) on contaminant removal efficiency in free water surface flow constructed wetland (FWSFCW) using ordinary least squares regression and experimental data from a waste treatment facility in Ghana. The results showed that environmental factors did not systematically vary across the experimental group and control set-up. Generally, the environmental factors explained relatively far less of the variance in contaminant removal efficiency compared with the plant species (Typha latifolia, Ruellia simplex and Alternanthera philoxeroides). Environmental factors cumulatively explained only 1.3%, 16.4%, 22.6%, and 5.6% of the variance in removal efficiency of BOD, COD, oil and grease, and total coliform bacteria, respectively. Temperature was the most important environmental predictor of the removal of BOD and phosphorus whereas DO was most important for removing nitrates and total coliform bacteria. ORP and pH were the most important predictors of COD, and oil and grease, respectively. These findings underscore the complex relationships among environmental factors and contaminant removal efficiency and the need for contaminant management practices and remedial techniques that address these complexities.

The objectives of this study were to assess the black soldier fly larvae (BSFL) composting potential and to analyse the quality of organic fertilizer produced for agricultural purposes. The waste biodegradation was determined by varying waste feed treatment (2, 2.5, 3.0, 3.5, to 4 kg) and control treatment of (2 kg) of heterogeneous mixture of municipal organic solid waste from market, restaurant and households. Each of the setups received equal number of viable larvae (i.e. 2000) which were 5–6 days old. To analyse the nutrient concentration of the compost residues with BSFL, the substrate and final compost were evaluated based on the levels of NPK as well as the C:N ratio. To evaluate the toxic levels of the final compost in terms of heavy metals, the presence and levels of As, Cd, Fe, Pb and Ni were investigated. The analysis showed that there was high percentage increase of nitrogen, phosphorus and potassium levels, i.e. 41.2% (SD ± 0.71%), 32.4% (SE ± 0.2%) and 77.1% (SE ± 0.19%), respectively. It was found that the larvae degraded more than half of the total substrate within 2 weeks. The study showed a decrease in heavy metal concentrations after larvae composting. The study revealed that the concentration of NPK increased significantly among the treatment groups. The study further revealed that some of the heavy metals under investigation had reduced to an acceptable level according to the standards of both local and international regulatory bodies.

Constructed wetlands have been proposed to address the frequency and magnitude of oil and gas-related environmental contamination. The effect of co-variation of hydraulic load and hydraulic retention time on the dynamics of contaminant removal efficiency of heterogeneous plant species was assessed using ordinary least squares regression. The results showed that hydraulic load (HL), hydraulic retention time (HRT) and plant species jointly explain 87%, 79%, 83%, 85% and 66% of the total variance in removal efficiency of conductivity, TDS, BOD, COD, and total coliform bacteria, respectively. The models also explain 86%, 80% and 81% of the variations in removal efficiency of oil and grease, total phosphorus, and nitrate. More than 90% of the explained variance of total coliform removal efficiency is jointly attributable to hydraulic load and retention time. Hydraulic load of 1000 L and retention time of 72 h (1000 L 72 h) recorded optimum removal efficiency for TDS and conductivity. Optimum removal efficiency for BOD, COD and total coliform bacteria were achieved at HL and HRT of 1000 L 72 h, 1000 L 48 h and 1250 L 24 h, respectively. Alternanthera philoxeroides recorded the highest removal efficiency for oil and grease, conductivity and TDS, whereas Ruellia simplex recorded the highest removal efficiency for COD. Typha latifolia had the highest removal efficiency for total phosphorus and nitrate. Plant species suppressed the relationship between HL and HRT (1250 L 48 h, 1500 L 72 h, 1750 L 48 h and 2000 L 48 h) and removal efficiency for conductivity. Similarly, plant species suppressed the relationship between 1000 L 48 h and 1750 48 h and removal efficiency for TDS. These relationships underscore the complex dynamics between optimal contaminant removal efficiency and required hydraulic load, hydraulic retention time and plant species.

The rate of ventilation through the vent pipe of a ventilated improved pit latrine is the main technical factor that determines its efficiency in odour control aside the maintenance and cleaning practices of the users. Even though the factors affecting the ventilation rate have been well researched, they have not been previously related in a mathematical model to quantify the relative effect of the various factors on the ventilation rate. The objective of this paper is to develop such a model that could be used to optimise and predict the ventilation rate as a function of relevant design criteria and weather conditions. The ventilation rates produced by various design modifications in an experimental ventilated improved pit latrine were measured under monitored weather conditions. A linear regression model was used to assess the relative effect of the various design modifications and the elements of weather on the ventilation rate. It was found that the diameter of the vent pipe is the most important factor which accounts for 53% of variations in the ventilation rate, followed by the external wind speed, which accounts for 25% of changes in ventilation. The provision of windows in other sides of the superstructure other than the windward side leads to a reduction of 32% in the ventilation rate and accounts for 9% of the variations in the ventilation rate. A regression model developed in this study could be used to optimise and predict the ventilation rate based on a set of design criteria and meteorological data.

The objective assessment of the level of odour in on-site sanitation systems is required when evaluating emerging technology options and maintenance practices. The purpose of this study was to measure the concentrations of hydrogen sulphide and ammonia as surrogates of odour using a portable gas detector, and assess whether the concentrations of the compounds correlate with the perception of users of the facilities. The Aeroqual 500 portable gas detector with hydrogen sulphide and ammonia sensor heads was used to measure the concentrations of the compounds in 88 private and seven communal latrines sampled from a peri-urban community in Ghana. The odour perception of 189 and 165 users of private and communal latrines, respectively, was assessed on an ordinal scale. It was found that the concentrations of hydrogen sulphide and ammonia measured with the gas detector reflected the known variation of odour levels among different technology options and the perceptions of the latrine users. The concentrations of hydrogen sulphide measured in the water closet, ventilated improved pit (VIP) and the simple pit latrines were 0.01, 0.03 and 0.13 ppm, respectively; those of ammonia were undetected for the water closet, and 0.30 and 3.27 ppm for the VIP and simple pit latrines, respectively. The Pearson correlation coefficient between hydrogen sulphide concentrations and user perception of odour (−0.234) was significant at 5 % level (p = 0.022) but that for ammonia was not. The results indicate that a portable hydrogen sulphide detector may be employed to objectively assess the effectiveness of new latrine designs and maintenance practices aimed at reducing odour in latrines.

Regular usage of latrines is crucial to public health. This study was conducted in a Ghanaian peri-urban setting to understand the factors that influence the usage of household and communal latrines and to discuss potential interventions to address existing barriers to regular usage. Data was collected using household survey questionnaires orally administered to 189 and 283 respondents with access to private and communal latrines respectively, five focus group discussions with gender and age groups, as well as observations at latrines. It was found that only 15 % of households had access to latrines at home while the rest depended on communal latrines or practised open defecation. The ventilated improved pit latrine was the commonest technology used by 47 % of households with private latrines. The residents ranked safety and privacy as the most important factors that influenced their decision to use any latrine. For private latrines, desludging challenges (14 %) and intense odour (7 %) were the most significant technical barriers while the most significant non-technical barriers were lack of immediate access when the latrine is locked or busy (28 %). For communal latrines, the major technical barrier was intense odour (23 %) while the major non-technical barriers were distance to latrines (28 %), user fees (21 %) and unhygienic conditions (7 %). Regular latrine usage in the study setting may be enhanced by technical support to address desludging challenges and control odour in latrines, as well as social interventions to make communal latrines affordable and more hygienic.

The paper presents an evaluation of post-project impacts of the Barekese Dam on three riparian communities downstream about 30 years after its construction. A network diagram, which incorporated a mathematical model, was used for impact identification and analysis. The expected environmental impacts, expressed as quantitative weighted impact scores, showed that the dam appeared to have exerted adverse impacts on the environmental quality of the communities. The impacts in the communities, however, increased with relative distances away from the dam and the river suggestive of cumulative impacts transmitted downstream. Strategic measures for improving environmental quality of the communities have been given.

Background Despite its contribution to global disease burden, diarrhoeal disease is still a relatively neglected area for research funding, especially in low-income country settings. The SNOWS consortium (Scientists Networked for Outcomes from Water and Sanitation) is funded by the Wellcome Trust under an initiative to build the necessary research skills in Africa. This paper focuses on the research training needs of the consortium as identified during the first three years of the project. Methods We reviewed the reports of two needs assessments. The first was a detailed needs assessment led by one northern partner, with follow-up visits which included reciprocal representation from the African universities. The second assessment, led by another northern partner, focused primarily on training needs. The reports from both needs assessments were read and stated needs were extracted and summarised. Results Key common issues identified in both assessments were supervisory skills, applications for external research funding, research management, and writing for publication in the peer-reviewed scientific literature. The bureaucratisation of university processes and inconsistencies through administration processes also caused problems. The lack of specialist laboratory equipment presented difficulties, particularly of inaccessibility through a lack of skilled staff for operation and maintenance, and of a budget provision for repairs and running costs. The lack of taught PhD modules and of research training methods also caused problems. Institutionally, there were often no mechanisms for identifying funding opportunities. On the other hand, grantees were often unable to understand or comply with the funders’ financial and reporting requirements and were not supported by their institution. Skills in staff recruitment, retention, and performance were poor, as were performance in proposal and paper writing. The requirements for ethical clearance were often not known and governance issues not understood, particularly those required by funders. Conclusions SNOWS believes that working with African universities to develop networks that support African-led research driven by the local context is an effective approach to develop and retain research skills needed to change policy and practice in water, sanitation, and hygiene in Africa. Electronic supplementary material The online version of this article (doi:10.1186/1478-4505-12-68) contains supplementary material, which is available to authorized users.