@phdthesis{Okofo2023, author = {Okofo, Louis Boansi}, title = {Hydrogeological assessment for evaluating the feasibility of managed aquifer recharge in Northeastern Ghana}, doi = {10.26127/BTUOpen-6244}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-62444}, school = {BTU Cottbus - Senftenberg}, year = {2023}, abstract = {In the Garu-Tempane area and Tamne River basin of north-eastern Ghana, granitic aquifers supply nearly 80\% of annually abstracted groundwater. Rapid and diffuse recharge enters the fractured and weathered Tamnean Plutonic Suite aquifers mainly granitoid, which are the dominant rock types in the study area. However, a greater challenge to the water supply in the area is posed by global climatic changes and overexploitation due to population growth. The semi-arid nature of the area together with the factors mentioned earlier has caused water scarcity, particularly in the dry season and these have affected the livelihoods of the farmers who depend mostly on the groundwater for irrigation and domestic purposes. A promising way to balance water resources in the region is using engineering technology such as managed aquifer recharge (MAR). MAR augments water levels in water-scarce areas and represents a key tool in water supply management. For this reason, a comprehensive hydrogeological characterization involving the hydrochemistry of the groundwater, groundwater recharge process and residence time using multi-environmental tracers, and a numerical groundwater flow model was developed. Based on the hydrochemistry results, the water quality index showed that the groundwater is very suitable for drinking. However, about 10.5 \% out of the 38 groundwater samples had elevated nitrate concentrations exceeding the permissible WHO drinking water limit. These are mainly agricultural areas, which might have influenced the elevated nitrate concentrations. Groundwater age dating using sulphur hexafluoride (SF6) and chlorofluorocarbons (CFCs) was used to date shallow groundwater in Ghana for the first time. The results proved that the mean residence time of groundwater was around 30 years, an indication of young groundwater and rapid groundwater renewability. The findings also showed different groundwater ages implying diffused flow systems occurring in the fractured granitic aquifer. Investigation of the groundwater recharge using stable isotopes of deuterium and oxygen-18 revealed that the main source of groundwater recharge is of meteoric origin. There were little or no contributions from the stream and ponds as they were subjected to evaporative fractionation during the dry season. The White Volta River samples and samples from two big rivers were depleted in heavy isotopes, which suggested a hydraulic connection between them and the groundwater. The numerical groundwater flow model was used to assess the feasibility of MAR and determine the maximum recharge and abstraction rates. The results showed that the aquifer had enough storage to accommodate enough volumes of floodwater without causing groundwater mounding. This shows that MAR is feasible in augmenting the water levels in the area when irrigation and domestic withdrawals are regulated.}, subject = {Managed aquifer recharge; CFCs; SF6; Numerical groundwater flow modelling; Northeastern Ghana; Schwefelhexafluorid; Fluorchlorkohlenwasserstoffe; Grundwasserstr{\"o}mungsmodell; Nordost-Ghana; Ghana (Nordost); Wasserversorgung; Grundwasser{\"u}berwachung; Grundwasserbildung; Grundwasseranreicherung; Numerische Str{\"o}mungssimulation}, language = {en} } @article{OttoAlipoursarbaniTorrentetal.2023, author = {Otto, Pascal and Alipoursarbani, Mozhdeh and Torrent, Daniel and Latorre-P{\´e}rez, Adriel and Paust, Thomas and Albert, Alfred and Abendroth, Christian}, title = {Microbiome characterization after aerobic digestate reactivation of anaerobically digested sewage sludge}, doi = {10.3390/fermentation9050471}, year = {2023}, abstract = {A demonstrator plant of a recently patented process for improved sludge degradation has been implemented on a municipal scale. In a 1500 m3 sewage sludge digester, an intermediary stage with aerobic sewage sludge reactivation was implemented. This oxic activation increased the biogas yield by up to 55\% with a 25\% reduction of the remaining fermentation residue volume. Furthermore, this process allowed an NH4-N removal of over 90\%. Additionally, 16S rRNA gene amplicon high-throughput sequencing of the reactivated digestate showed a reduced number of methane-forming archaea compared to the main digester. Multiple ammonium-oxidizing bacteria were detected. This includes multiple genera belonging to the family Chitinophagaceae (the highest values reached 18.8\% of the DNA sequences) as well as a small amount of the genus Candidatus nitrosoglobus (<0.3\%). In summary, the process described here provides an economically viable method to eliminate nitrogen from sewage sludge while achieving higher biogas yields and fewer potential pathogens in the residuals.}, subject = {Anaerobic digestion; Anaerobic microbiomes; Aerobic sludge activation; 16S rRNA sequencing; Water treatment; Belebtschlammverfahren; Schlammfaulung; Mikroorganismus; G{\"a}rung; Biogas; Stickstoff-Elimination; Anaerobe Verg{\"a}rung; Anaerobe Mikrobiome; Aerobe Schlammaktivierung; 16S-rRNA-Sequenzierung; Wasserversorgung}, language = {en} } @phdthesis{Mbua2013, author = {Mbua, Roy Lyonga}, title = {Water supply in Buea, Cameroon : analysis and the possibility of rainwater harvesting to stabilize the water demand}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus-29522}, school = {BTU Cottbus - Senftenberg}, year = {2013}, abstract = {Water scarcity is a global phenomenon which affects close to 2.8 billion people worldwide especially in developing countries. Buea (Cameroon) is blessed with abundant water resources but paradoxically the inhabitants of this region are facing a serious water crisis. The increase in population and rapid urbanization exert tremendous pressure on the water resources of this community. Also, the capacity of the main water supply authority CAMWATER (Cameroon Water Utilities Corporation) is insufficient to cater for the 90000 inhabitants. This thesis explores the potential of domestic rainwater harvesting (rooftop rainwater harvesting) as the best alternative to fulfill the water demand of the population. It also promotes artificial groundwater recharge as the best way to sustainably deal with excess rainwater to decrease surface runoff and avoid flooding especially in the high altitude villages on the eastern slopes of Mount Cameroon during the rainy season. Furthermore, it examines the willingness of the community to accept this innovative alternative which will solve their water supply problems. In an effort to combat water scarcity and decrease poverty in this region, this research analyses the possibility of domestic rainwater harvesting as a worthwhile alternative to augment the present conventional water supply systems to stabilize the water demand and create avenues for economic development. Buea has high rainfall (4000mm/year); harvesting the rainwater during the rainy season, storing it for usage in the dry season and using the excess to recharge groundwater aquifers will definitely ameliorate the status quo. To realize these objectives, a series of double ring infiltration tests were carried out in 9 different locations. The aim of these tests was to measure infiltration rates and therefore locate areas of good artificial groundwater recharge potential. Also, 220 questionnaires were distributed in 10 villages within the municipality in an effort to characterize the water consumption pattern of the population. The study confirms that the Buea water crisis is mainly as a result of poor water management and not due to physical or economic water scarcity. It reveals that about 86\% of the population experience water shortages and CAMWATER has to double up its present capacity in order to meet up with demand. Over 80\% of the population is willing to consider rainwater harvesting as a good alternative to augment their domestic water supply if government provides subventions to cover half of the installation costs. Conclusively, domestic rainwater harvesting if carried out extensively will rescue the Buea population from a disastrous water deficiency leading to detrimental environmental problems.}, subject = {Buea; Regenwasser; Wasserversorgung; Kamerun; Regenwasserbewirtschaftung; Wasserbedarf; Wasserversorgung; Buea; Cameroon; Buea; Rainwater harvesting; Infiltration; Groundwater recharge}, language = {en} }