Wastewater discharged from the domestic household has proven to be a potential source for resource recovery. Apart from wastewater, kitchen organic waste contains an enormous amount of energy in terms of organic content and nutrients such as TKN and TPH. Now that the disposal of waste into landfills is prohibited in most parts of Europe, one of the options is to divert the organic waste to wastewater treatment plants using kitchen waste grinders (KWG). Since KWG is a water-consuming appliance, the installation of KWG with water conservation technologies may be a viable option in the future. This can aid efficient recovery of resources and reduce the drinking water demand. The evolution towards sustainable urban sanitation will lead to several positive and negative effects. Some of the positive effects, apart from resource recovery, are the possibility to postpone the enlargement of existing sewer systems, to construct new sewers of smaller pipe diameter and to lower energy consumption for sewage pumping. While the negative effects are blockage of sewer due to reduced flow rates, increased sedimentation and release of malodour in the contemporary sewerage system and increased treatment costs due to increase in COD oxidation and nitrogen or phosphorus removal. Eventually the low flow-high load wastewater needs to be transported through sewers and treated locally (decentralised treatment). In this study, an attempt was made to investigate the effect of coupling the effluent from KWG at various penetration rates such as 100%, 75%, 50% and 25% with water conservation scenarios on hydraulic and quality parameters in the sewerage system. Water conservation scenarios were onsite greywater and rainwater reuse and application of ultra-low water demand appliances. SIMDEUM was upgraded with the addition of an extra appliance in the form of KWG to generate stochastic discharge patterns with appliance specific wastewater flows and quality. The data generated was incorporated into the sewer network model, InfoWorks ICM to analyze the impact of the addition of KWG with water conservation strategies on the contemporary sewer network. The results obtained showed that there is an increase in the mass load of COD, TKN and TPH of 118%, 84% and 90% respectively and reduction in flow, velocity and shear stress of up to 54%, 49% and 74% respectively for the application of water conservation strategies with KWG. This substantiated the fact that the contemporary sewer system is not efficient in transporting the wastewater generated due to the addition of KWG along with water conservation strategies at the household level. A new sewer design with smaller diameters and steep slopes was used to study if the low flow-high load wastewater can be safely transported, in terms of adequate self-cleansing velocity and shear stress. The results from the investigation of new sewer design showed that 100% and 75% implementation of KWG with water conservation technologies will achieve self-cleansing capacity which will help prevent clogging and sedimentation for a piping network of 110mm diameter at a slope of 1:160. KWG market penetration rates of lower than 50% along with water conservation strategies might face issues of sedimentation and clogging. In conclusion, the up-gradation of SIMDUEM with KWG was successful to generate stochastic discharge patterns. This research has demonstrated that the application of KWG along with water conservation strategies may aid in resource recovery and reducing freshwater demand in the urban water cycle. The accomplishment of implementation of KWG with water conservation strategies is not realistic in the contemporary sanitary system however, this transition can be adopted in new urban developments with efficient design of wastewater transport and decentralized treatment system. Further research is required into the feasibility of a decentralised resource recovery system for the implementation of KWG with water conservation strategies.

The temperature of drinking water is an important parameter, affecting physical, chemical, biological and aesthetic properties of the water. Currently, measurements exceeding the legal limit of 25ᵒC at the tap are exceptional. However, there are reasons to believe that the number of exceedances will increase due to climate change and urbanization. So far the effects of sunlight hours and soil coverage on drinking water temperature have already been quantified quite well. Still lacking is the exact effect of anthropogenic heat sources on these temperatures. In this study more insight is given in the extent of this effect for Rotterdam, and measures are discussed to mitigate or to prevent drinking water warming. First, potential anthropogenic heat sources are identified. By analyzing data on tap temperatures and old soil temperature measurements, several anthropogenic heat sources emerged. A map of the statistically warm drinking water temperatures in Rotterdam, appears to have a lot of resemblance to the city heating system whereabouts. Furthermore, smaller indications point at high voltage power cables and metro lines to be important anthropogenic heat sources. Soil temperature measurements around these potential heat sources confirm some of the expectations. Around high voltage power cables, a limited elevated temperature of 0.6ᵒC is found. Much more alarming results were encountered around the city heating mains. In autumn, primary heating mains warm-up the soil by 4.9 – 5.3ᵒC and secondary heating mains do so by 2.9ᵒC. A temperature elevation of 1ᵒC is measured to a distance of 3.8 - 5.25m and 2.3m, respectively. However, these results are highly dependent of several parameters, like the temperature differences between the air and soil, the thermal properties of the soil, and the depth and state of the anthropogenic heat sources themselves. Several strategies to mitigate the warming of drinking water in the distribution system are applicable. In a general sense, it is most sensible to create a distance between any heat source and the distribution system. By placing drinking water mains in the shade, below grass and away from anthropogenic heat sources, warming of the drinking water can be prevented in a relatively inexpensive manner. Measures targeted at temporary local hotspots can be focused on restraining the heat flux from the heat source to the soil, the heat flux through the soil, and the heat flux from the soil to the drinking water.

Intensive urbanisation enhances warming of cities’ ambient and subsoil environment. The local drinking water distribution system (DWDS) is likewise affected. Hotspots of anthropogenic heating were perceived to influence drinking water temperature and pose a threat for microbial drinking water quality. Information on temporal and spatial relation between drinking water temperature and microbial indicating parameters was however scarce. This is especially the case for a full scale unchlorinated DWDS in a metropolitan area. Therefore, this research aimed to explore the spatial and temporal relation between drinking water temperature and microbial indicating parameters Aeromonas and Heterotrophic Plate count (HPC). 11 Years of sample data from the DWDS in the metropole of Amsterdam was explored, with the objective to possibly draw conclusions beyond this DWDS. This DWDS consists of two interconnected subsystems. Each subsystem is fed by its own treatment facility. Areas with repetitive exceedance of threshold temperature (14 oC) for accelerating Aeromonas growth, were not inextricably tied to repetitive exceedance of the Aeromonas standard for safe drinking water. Areas with repetitive exceedance of the Aeromonas standard were often linked to prolonged residence time. For regions on the outskirt of observed DWDS it was suggested that the influence of residence time was more important than the absolute water temperature to explain Aeromonas concentrations.