The aim of the investigation was to compare the performance of an anaerobic baffled reactor (ABR) with a completely mixed anaerobic reactor (CMAR). The ABR was operated with a hydraulic retention time (HRT) of 20 h while the CMAR was operated at 20 d. A control experiment was conducted with a CMAR operated at a constant hydraulic retention time and substrate feed concentration. During the first phase, the start-up performance of the ABR and CMAR were compared. In the second phase of the study the steady state COD removals were compared. The laboratory completely mixed anaerobic reactor was a 20L glass vessel with a stirrer coming in through the neck. A second type of reactor, anaerobic baffled reactor (ABR) was also operated. The ABR was a rectangular perspex box with internal vertical baffles alternately hanging and standing. The baffles divide the reactor into eight compartments with a total working volume of 7.5 L. Each baffle is angled at about 45Q to distribute the flow towards the centre of the upcomer. The reactors were seeded with raw sewage and allowed to stand for 3 days after which a continous feed of sucrose and basal salts was commenced. The initial HRT for the ABR and the CMAR were 60 h and 30 days respectively. When the reactors reached steady state (pH, gas production, gas composition and alkalinity), the HRT was reduced in a stepwise fashion (ABR 60 h to 35 h to 20 h and CMAR 35 d to 30 d to 20 d). At the final HRT the COD removals were similar (67 %). The ABR took 120 d to attain final steady state while the CMAR took 200 d. The organic loading tests were undertaken with a stepwise increase (doubling) in the influent substrate concentration. The feeding commenced at an organic loading rate (OLR) of 4.8 kg/m(3).d for the ABR. The flow rate (HRT) into both reactors and other parameters were kept constant (HRT of 20 h and 20 d for ABR and CMAR respectively). The substrate concentration was increased from 4 gCOD/L (4.8 kg/m(3).d) to 64 gCOD/L (76.8 kg/m(3).d) for the ABR. For the CMAR it was increased from 4 gCOD/L (0.25 kg/m(3).d) to 32 gCOD/L (2 kg/m(3).d). The method used was to increase the organic loading rate until the reactors failed. Since the two reactors had different operating HRTs, the tests began when both had the same COD removal rate of about 60 % COD reduction. The same parameters as in the start-up period were monitored for both reactors. The CMAR had a COD removal efficiency ca. 70 %, which did not fluctuate when OLR was increased. The ABR reached a maximum COD removal of 80 %. An increase in the OLR led to an initial decrease in the COD removal until the biomass recovered and the high COD (80 %) removal rates resumed. The ABR reached a maximum OLR of 76.8 kg/m(3).d whilst the CMAR reached a maximum OLR of 2.0 kg/m(3).d. The investigations showed that the ABR could be operated at higher organic loads than the CMAR and give the same organic removal rate. This verified the importance of increasing the SRT/HRT ratio in anaerobic reactors. The CMAR, however, proved to be stable to changes in the influent feed strength, as there was no immediate noticeable changes in the gas production. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2000.

A research report submitted to the Faculty of Humanities, University of Witwatersrand, Johannesburg in partial fulfilment of the requirements for the degree of Master of Arts in Development Studies March 2015 / The research report presents an analysis to, responses to and dynamics around the municipal water problems in Harare, Zimbabwe using the case of two residential suburbs namely Mabvuku and Greendale (one high density and the other one low density respectively). The key questions that inform this research report are as follows: How has the on-going urban water crisis affected residents‟ lives in the suburbs of Greendale and Mabvuku in the city of Harare, Zimbabwe?; how does party politics affect the delivery of municipal water in Greendale and Mabvuku?; and, what are the environmental consequences of the municipal water crisis? The findings from this study contribute immensely to an understanding of the consequences of and various issues and, the key players underlying the protracted problem of municipal water availability in the city of Harare. The study argues that the prevalence of partisan politics and political power struggles in Harare are at the heart of the municipal water problems faced by Mabvuku and Greendale. In this regard, the study critically interrogates the relationship between the central ZANU–PF government and Movement for Democratic Change (MDC)-led local government and tries to understand the ramifications it is having on municipal water services. Interestingly the study also reveals that, despite the differences in coping strategies by residents of Mabvuku and Greendale, both locales have not been passive victims of the municipal water crisis. Instead, residents from both suburbs employ strategies according to their needs to ensure survival. However, despite some of the coping strategies (such as borehole and well drilling) significantly helping residents to manage and avert the water stress in light of the absence of municipal tap water, the study presents, explores and discusses the environmental consequences that are likely to happen as a result of the high concentration of these alternative water sources. / GR2017

PhDRDV / Institute for Rural Development / Throughout the world, irrigation is appreciated because of its immense contribution to agricultural production, food and nutrition security, combating poverty and enhancing development, especially in rural areas. The worsening effects of climate change on rainfall patterns as well as food and nutrition insecurity in sub-Saharan Africa are elevating the importance of irrigation schemes in smallholder farming. However, studies conducted in sub-Saharan Africa indicate that the performance of irrigation schemes remains suboptimal. In addition, the studies are highly skewed towards technical and physical dimensions of the schemes and ignore social aspects such as gender. Consideration of gender imperatives would help define and structure who uses water, when and how. This situation necessitated carrying out the PhD thesis research, aiming to explore and explain inherent gender dynamics in water use and management. The ultimate aim was to propose intervention strategies anchored on differential gender power dynamics embedded in irrigation water use in smallholder irrigation schemes. Specific objectives adopted for the study of the Nyanyadzi irrigation scheme in Manicaland Province of Zimbabwe were to: 1) assess the gendered nature of irrigation water use; 2) determine the gendered nature and extent of participation of male and female members of the irrigation scheme in water management; 3) identify the gendered challenges and constraints to irrigation water use; and 4) propose strategies for improved access and management of water. An exploratory sequentially integrated mixed method research design was used in the two phased PhD studies. Seventy three farmers (26 men and 47 women) were the respondents in the first phase in which qualitative data were collected. The gender analysis matrix and activity profile were used to gather and document the perceptions of men and women farmers relating to use of irrigation water. One hundred and nine conveniently sampled respondents (47 men and 62 women) were the source of data in the second phase of the study, which was quantitative and confirmatory in nature. A questionnaire, requiring responses on a Likert-type scale ranging from 1 (strongly disagree) to 5 (strongly agree) was used to collect data. Qualitative data collected during the exploratory phase were analysed using the Cresswell (2013) Thematic Content Analysis technique. Pair-wise ranking was conducted to determine the major constraints to access, use and management of irrigation water. The Predictive Analytics Software Statistics 18 for Windows (PASW Inc: Chicago, IL, USA) was used to analyse quantitative data. Gender, age, marital status, location of irrigation plot, plot ownership and level of education were the independent variables used. Dependent variables included nature of water use, participation in water management and constraints to water use. Cross-tabulation was carried out and the iii Pearson’s Chi-square test for association used to establish if relationships existed between variables. Statistical significance was considered at P < 0.05. The Cramer’s V post-hoc test was performed to measure the strength of association of the perceptions which the Chi-square test had determined to be significantly different. The uses of canal water were found to be varied and gendered. More women than men used canal water for reproductive purposes such as laundry and bathing. Highly significant positive associations (P < 0.01) were observed among gender, age, marital status, ownership of irrigation plot and level of education with use of irrigation water for laundry, bathing, livestock watering and other communal uses. However, location of plot was not associated with different types of water uses (P > 0.05). With respect to farmers’ participation in meetings, contributing in meetings, repair of canals, provision of labour in canal maintenance, hiring labour for canal maintenance and contributing cash for canal repairs and maintenance, highly significant positive associations (P < 0.01) were observed with gender, age, marital status, level of education, and ownership and location of irrigation plot. Level of education of the farmer was observed to be not associated with his/her attendance of meetings (P > 0.05). Plot location was negatively associated with participation, provision of labour for maintenance, contribution of cash and hiring labour for canal repairs (P > 0.05). Exorbitant payments for using water were regarded as the major constraint to performance of the smallholder irrigation scheme. Highly significant positive associations (P < 0.01) were observed between gender and plot location, and all the constraints to water use that the farmers identified. The constraints ranged from unequal water distribution between and within men and women, and upstream and downstream farmers; unfriendly water delivery times; conflicts and corrupt practices in water distribution; and discrimination with respect to schedules of delivering water. Overall, gender imbalance in the use and management of irrigation water existed. This was evident in the disparities in uses and users of canal water that followed gender and social lines. Men dominated decision making in water management, especially in meetings. In contrast, women dominated in implementation stages mainly in relation to provision of labour for cleaning and maintaining water canals. Considering all the results obtained in the current study, it can be concluded that a combination of socio-economic and socio-cultural factors caused the water problems that the Nyanyadzi irrigation scheme experienced. The need for introducing gender-sensitive interventions in use and management of irrigation water was evident. Thus, gender needs, roles and responsibilities should be reconceptualised so as to align them with the socio-cultural context of the Nyanyadzi community. In addition to this, the fact that both men and women iv are not homogeneous interest groups should be factored into irrigation water management. Lastly, it is crucial to incorporate various social hierarchies that interact with gender to influence irrigation water use and management. How this can be done deserves further scientific investigation. / NRF

The study investigates the contribution of WDM towards mitigating scarcity of potable water in cities with particular reference to Bulawayo.WDM origins and its successes are traced. The study classifies scarcity representations into four categories and reveals that the scarcity in Bulawayo satisfies all the four representations hence calls it total scarcity. The research employed document study, questionnaires, interviews and a focus group to collect data. Document study revealed that water restrictions successfully mitigate the scarcity in Bulawayo. Field work partially confirmed the usefulness of WDM in the life of the city and revealed the need to synchronize the conceptualizations of WDM among different stakeholders in order for the paradigm to do even more in terms of mitigating scarcity. The results were interpreted in terms of TPB. The key recommendation of the study is that the city invests in water use behaviour change in order to realise huge water savings. / Development Studies / M.A. (Development Studies)

The study investigates the contribution of WDM towards mitigating scarcity of potable water in cities with particular reference to Bulawayo.WDM origins and its successes are traced. The study classifies scarcity representations into four categories and reveals that the scarcity in Bulawayo satisfies all the four representations hence calls it total scarcity. The research employed document study, questionnaires, interviews and a focus group to collect data. Document study revealed that water restrictions successfully mitigate the scarcity in Bulawayo. Field work partially confirmed the usefulness of WDM in the life of the city and revealed the need to synchronize the conceptualizations of WDM among different stakeholders in order for the paradigm to do even more in terms of mitigating scarcity. The results were interpreted in terms of TPB. The key recommendation of the study is that the city invests in water use behaviour change in order to realise huge water savings. / Development Studies / M.A. (Development Studies)