The rapid economic and population growth recently drives Maputo to become more metropolitan, with construction sector as one of the pillars to support its transformation. This progressive move is, however, hindered by one of the most crucial problems: water scarcity. Water is essentially required by construction sector, especially in concrete production. It needs a proper quantity and quality to meet the expected strength. While the quantity is determined by its ratio with cement, the quality varies for plain, structural and high-strength concrete. Drinking or tap water is commonly used in Maputo but previous experiments worldwide show that there is a possibility to use non-drinking water for concrete production. One of the emerging alternatives is treated sewage. This thesis aims to assess whether reclaimed water from the sewage can be used as a source for concrete production in Maputo in order to save tap water for domestic purposes. To determine water demand from the concrete companies, 156 concrete companies in Maputo and its surrounding, Matola and Machava, were listed and 11 of them were interviewed with the variance of locations, types of products, production methods, existing water source, number of employees, monthly water tariff, current practices and willingness to cooperate for a preliminary water reclamation project. The average amount of water consumption for 11 interviewed companies is 311 ± 36 m3/day and for the actual population of 156 companies is 4411 ± 257 m3/day. This value contributes to 12% - 14% from the total tap water use in Maputo. The water price is approximately €0.76/m3 for the small companies and €0.38/m3 for both the medium and large companies. The potential supply sources were investigated from different types, flow rates and locations, such as the outlet endpoints from houses, the wastewater treatment plant and the effluent from other industries. The influent of the wastewater treatment plant was considered the best source for the preliminary plant design with a flow rate of 5682 ± 1196 m3/day. Available standards worldwide and previous works were studied to find the safe ranges of water quality for concrete. Field and laboratory measurements were also conducted to provide preliminary information. The results were used as the basis for designing a treatment plant from the demand of 11 interviewed companies, with lower effluent quality than tap water, yet sufficient for concrete production. Recommendations of a large scale plant for all 156 companies were also presented. The system is designed as a modular scheme to provide different effluent qualities and potential changes, such as the increase of the influent flow rate, the option of combining the new system with the existing plant, etc. The system is divided into four phases. Phase 1, consisting of a coagulation tank (1 x 0.6 x 0.5 m), four flocculation tank (1.5 x 1 x 1 m) and a dissolved air flotation tank (1.6 x 1.4 x 1 m), removes fat, oil and grease, phosphorus and suspended solids. Phase 2 removes remaining suspended solids by a rapid sand filtration (1.50 m bed depth x 0.56 m diameter x 5.45 m height). Phase 3, comprising nine units of nanofiltration in one skid, removes dissolved solids to meet the demand of higher strength concrete. The last phase is disinfection which were excluded since the removal capacities from the previous phases are already sufficient. The cost of the design is divided into three packages depending on the expected effluent quality from each company. The basic package only consists of phase 1 and costs €0.30/m3. The intermediate package, comprising phase 1 and 2, costs €0.40/m3. The advanced package, consisting of phase 1 and 3, costs €0.80/m3. Only the price of the advanced package is higher than the actual tap water price. Pumps are installed before the units of rapid sand filtration and nanofiltration. Valves are incorporated to divide the flow for different treatment packages. The delivery of the effluent is performed by renting trucks since it is less expensive than constructing new pipelines. The design shows that producing concrete with reclaimed water from treated sewage is possible to be performed in Maputo and the sewage does not need to reach drinking water quality. It is the starting point to increase the availability of usable water and the opportunity of supplying tap water as much as possible for domestic purposes.

In this study, the raw water intake, transmission pipeline and the PDAM Badaksinga Treatment Plant in the city of Bandung in West Java, Indonesia was researched in order to evaluate the increase of capacity of Treatment Plant in order to satisfy the water demand of the citizens of Bandung. For this purpose water quality and flow measurements from the raw water intake, flow measurements along the transportation to the treatment plant and the water quality at the treatment plant were done to obtain an integral view of the current situation. The raw water intake from Cikalong area in the south of Bandung was observed in this project. It comes mainly from the outlet discharge of PLTA Cikalong, the hydropower plant (3000L/s – 8000L/s with better water quality), and alternatively from Cisangkuy River (500L/s). The contribution of these two sources, along with their water quality and the efficiency of presedimentation tanks, were investigated through field measurements and historical data observation. This study gives the indication that the quantity of water is generally sufficient but it needs some mechanisms to have a daily constant flow. A seasonal cycle storage mechanism and presedimentation tanks behaviour are recommended as an alternative solution and a consideration. The new transmission pipeline, Pipa Baru, was focused for research in this project. This pipeline had three main problems which included the occurrence of bursts, never functioning at full capacity, and lacking accurate flow measurements. These problems were tackled through field measurements and simulations. For the first two problems, the results showed that air stagnation may be the cause of the problem. The accuracy of flow measurements can be overcome by more training and calibration of the SCADA, the online measurement device of the plant. Concerning the water quality, even when most of the times the effluent of PDAM Badaksinga Treatment Plant meet the environment and legal standards, the system is not robust and vulnerable to any change in the influent due to the lack of monitoring, therefore the frequency of monitoring should be increased, moreover online devices should be installed. Furthermore, the removal of certain parameters should be studied in the future and special attention should be given to the PAC dose to know the exact amount of aluminum that is dose in order to enhance the performance of the following units (sedimentation and filtration) and consequently to produce a better and safer water quality. It should be noted that the expertise of the operators is an advantage, so that training should be given to the operators in order to update the knowledge. Furthermore, in relation to the operation and equipment more improvements, investments and preventive maintenance need to be done to enhance the performance of the complete water supply system of PDAM.