Last decades the concern about energy consumption has globally arisen due to awareness on climate change and the increase of energy prices. In the water field the nexus between water and energy has been extensively studied, however, there has been little discussion about energy-efficient specific approaches. This master thesis is part of the OPTIWELLS project which addresses to determine more energy efficient techniques for water supply operation, in particular for water abstraction well fields. One option to optimize a well field preserving its structure or components is the “smart well field management”, which maximize the time during which the pumps are performing on their best efficiency point, guaranteeing the water demand. The smart well field management is complex and accounts for various integrated processes. The aim of the project is to develop a prototype of a software tool able to cope with this complex optimisation problem. In particular, this master thesis deals with the modelling of a case study, applying methodologies that will be implemented in the OPTIWELLS prototype tool. Results and methods of data analysis for a well field, including a site audit, are described. The well field modelling was carried out with EPANET software by means of its Programmer’s Toolkit. No reliable data to validate the energy consumption estimation of the model were available. However, the report shows that observed hydraulic conditions of an abstraction well field can be accurately reproduced. The impact of different modelling approaches and amount of data available on energy evaluation is also drawn. Some insight into the well field current conditions (current pump curve, drawdown, water quality, specific energy demand,..) are discussed and recommendations or the operation of the case study site will be given.

Today, groundwater is one of the most important fresh water resources in big cities of the world. On one hand, the population growth and urban development and on the other hand, climate change and decreasing precipitation will increase the vital role of underground water resources to supply water for the cities, therefore an increase in the energy consumption in well fields has to be expected. It is becoming more difficult to ignore the cost of pumping energy for water stakeholders in Germany and Europe. In recent years, there has been an increasing interest in optimisation of energy consumption in different fields. The goal of this study is first to design a relational database to store the information of submersible pumps and second to develop a database management system for this pump database. The pump database is intended to be used in prototype model software aiming at the minimisation of a well field's pump energy demand. To this end, two approaches of assessing the necessary data for submersible pumps, and building a relational database are going to be discussed in this study. Finally, two applications with graphical user interfaces which have been developed by using the programming language “R” are presented for loading the data into the database, visualizing the database tables and plotting the pump curves.

Wastewater reuse is increasingly considered as possible alternative water source for diverse non-potable uses. Among the major questions, defining which water quality for which reuse is required is crucial. If the demand for reclaimed water is seasonal, the question of reclaimed water storage is also essential. Aquifer recharge for further nonpotable reuse can be a solution to address many final reuse applications, including indirect agricultural or landscape irrigation, saltwater intrusion barriers, subsidence mitigation/aquifer replenishment or other non-potable reuses. Most of the aquifer recharge applications of wastewater reuse so far rely on high-pressure membrane systems or even double-membrane combined with advanced oxidation processes. However, when non-potable reuse is targeted, or the replenishment of a threatened aquifer is planned, recharge with high-quality non-potable water could be envisaged as acknowledged by the legislation of several countries. In this report, the performance of hybrid disinfection/filtration and recharge schemes is assessed in comparison to a high-pressure membrane system working under similar conditions. Among the portfolio of available disinfection and filtration technologies, five treatment trains were chosen – combinations of ozone or UV treatment with sand filters or UF membrane and final infiltration or injection – and compared to a double-membrane system (UF+NF). A synthetic secondary effluent (SE) was considered for this conceptual study on the basis of a worldwide survey of typical SE water qualities. The major legislations from the WHO, the USEPA and Australian guidelines were considered to define the water quality to be reached by these hybrid treatment schemes. The low targeted value in suspended solids (10 mg/L) and microbiological contaminants (1 fecal coliform / 100 mL) requires extensive disinfection and filtration processes. The proposed schemes were selected on the base of a large review of typical pollutant removal efficiencies found in the literature. To perform a comparative Life-Cycle Assessment of the different treatment trains, similar assumptions were made in all cases for a hypothetical case study of a 50,000-PE reuse plant downstream of a secondary sewage treatment plant. All five proposed hybrid treatment trains are capable of supplying very high non-potable water quality, and the combination of disinfection, filtration and aquifer passage proved to be an efficient combination for removing suspended solids, residual BOD and microbiological contaminants. The environmental performance of the treatment trains was compared in terms of carbon footprint, but also energy demand, human toxicity, acidification impact and land footprint. Both the energy demand and carbon footprint of hybrid schemes was found to be considerably lower than for a double-membrane system, besides offering an additional storage solution in the aquifer. Thus, there is a significant margin for lowering the environmental impact, energy demand and operational costs if non-potable water quality is sufficient for the reuse goal. However, the legal context and social acceptability may represent barriers for this intended recharge of nonpotable water to the aquifer. This conceptual study has shown the potential of hybrid solutions to provide high-quality non potable water for aquifer recharge and further reuse. A large portfolio of solutions was proposed to reach the intended non-potable uses. To assist the selection of adequate treatment trains, the strengths and weaknesses of the solutions can be summarized in a decision tree taking into account the reuse goal, aquifer type and space availability, and selecting the least energy-intensive solution for a given legal and sociocultural context.

Different technologies for tertiary wastewater treatment are compared in their environmental impacts with Life Cycle Assessment (LCA). Targeting low phosphorus concentration (50-120 µg/L) and disinfection of WWTP secondary effluent, this LCA compares high-rate sedimentation, microsieve, dual media filtration (all with UV disinfection), and polymer ultrafiltration or ceramic microfiltration membranes for upgrading the large-scale wastewater treatment plant Berlin-Ruhleben. Results show that mean effluent quality of membranes is highest, but at the cost of high electricity and chemicals demand and associated emissions of greenhouse gases (GHG) or other air pollutants. In contrast, gravity-driven treatment processes require less electricity and chemicals, but can reach significant removal of phosphorus. In fact, the latter options will only lead to a minor increase of GHG emissions and energy demand compared to the existing pumping station or UV treatment.

A continuous monitoring, using UV-VIS spectrometers, was carried out in Berlin from 2010 to 2012. It combined (i) continuous measurements of the quality and flow rates of combined sewer overflows (CSO) at one main CSO outlet downstream of the overflow structure and (ii) continuous measurements of water quality parameters at five sites within the urban stretch of the receiving River Spree. Locally, the collection of data aims at (i) characterizing CSO emissions, (ii) assessing the local dynamics and intensity of CSO impacts on the river and (iii) calibrating sewer and river water quality models being part of a planning tool for future CSO management in Berlin (Riechel et al., 2011). UV-VIS spectrometers are in-situ probes, which measure absorbance spectra ranging from UV to visual wavelengths. Concentrations, such as chemical oxygen demand (COD), are calculated from these spectra. Due to the varying composition of waste and river water a local calibration is required to enhance the measurement quality. According to Gamerith et al. (2011), manufacturer global calibration can lead to systematic error up to 50% for COD measurements.

Asset management is an increasing concern for wastewater utilities and municipalities. Sewer deterioration models have been developed by research and municipalities to support the definition of cost-effective inspection and rehabilitation strategies. However, the acceptance of deterioration models among sewer operators and decision makers still raise considerable challenges. This article presents the state of the art of condition classification and sewer deterioration modeling and discusses key issues for the future development of deterioration models. Research is needed (i) to identify the most appropriate approaches for condition classification and deterioration modeling and (ii) to conclude clearly about their quality of prediction. Due to the high costs associated with CCTV inspection and data collection, the influence of input data on modeling quality and the optimal input data requirement are still to be evaluated. The ongoing project SEMA aims precisely to assess the suitability of models to simulate sewer deterioration. Objectives and strategy are shortly presented at the end of the article.

Recent infrastructure studies underline the general deterioration of sewer systems and the risk reversing public health, environment and increasing costs (ASCE, 2009). Aging pipes have not been inspected, replaced or rehabilitated rapidly enough to prevent sewer deterioration and increasing system failures (Tuccillo et al., 2010). According to a need survey conducted by EPA (2008), total funding needs for replacement, rehabilitation and expansion of existing collection systems for a 20 year period in the USA is 82.7 billions $, i.e. 28% of the total need of public agencies for wastewater treatment and collection. In the last 30 years, most municipalities have invested in sewer system expansion and treatment plant upgrade but a relatively small component has been allocated to the improvement of sewer system condition.

Managed Aquifer Recharge (MAR) is a means to replenish aquifers in case of over-abstraction and store water, especially in regions with semi-arid or arid climate. For water re-use schemes MAR can offer additional treatment in the subsurface so the CO2-footprint can be reduced. Pre-treatment via ozonation and dual media filtration before infiltration of treated wastewater was studied to compare the obtained water quality to guidelines for water reuse. While the removal of bulk parameters such suspended solids or chemical oxygen demand were easily reduced by ozonation and filtration, the disinfection turned out to be the limiting process.

To cope with occurring traces of organic contaminants in the effluent of waste water treatment plants, ozonation is a suitable technical treatment method. However, there is an ongoing discussion about the necessity of a posttreatment of ozonation effluents to remove possible toxic ozonation by-products. This study compares a dual media filter (DMF) and a biological activated carbon filter (BAC), which were used for ozonation post-treatment, and were also designed as coagulation filters for tertiary phosphor removal. The results of this study demonstrate that both rapid filters performed similarly in respect to DOC reduction and oxygen demand, and could also be used for tertiary phosphorus removal without any impairments. A comparison of a serial mode of the DMF and the BAC with a slow sand filter, which was used as a surrogate for an infiltration pond, showed that this two-stage process could increase the degradation of the DOC, but was not able to remove the entire biodegradable DOC.