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Greywater recycling systems in Germany - Results, experiences and guidelines

Authors:
  • Nolde - innovative Wasserkonzepte GmbH

Abstract

Although Germany is not considered a water-poor country, there exist regional differences in water supply and consumption. During the past 15 years, the greywater aspect has been dealt with in Germany with a greater interest and variable success. In addition to an increased environmental awareness, water costs also play an important role in increasing the demand for advanced greywater treatment plants nstalled in buildings. Under favourable conditions, the amortisation costs usually lie between 5 and 7 years. Systems that have been extensively tried and tested and have been shown to be most reliable are those employing an advanced biological treatment followed by an UV disinfection. Systems based on membrane technology are being developed and researched intensively in Germany for municipal wastewater treatment. However, so far they play no role in greywater recycling. Greywater systems operating under low energy and maintenance requirements without the use of chemicals are mostly favoured. In Germany, greywater recycling systems should be registered at the Health Office in order to guarantee that no cross-connections exist with the drinking water network and that pipes are labelled according to regulations. The hygienic requirements for recycled greywater, which is primarily used for toilet flushing, are oriented towards the EU-Guidelines for Bathing Waters. The use of recycled greywater for irrigation purposes is minor. As to the use of recycled water for laundry, the first promising investigation results are now available.
... Their height relates to the sum of the relationships between the elements. The increased interest in the topic of greywater recycling resulted in increased awareness of the risks associated with the use of greywater and the resulting sanitation requirements [115]. An often-discussed aspect of greywater recycling was the financial profitabil- The increased interest in the topic of greywater recycling resulted in increased awareness of the risks associated with the use of greywater and the resulting sanitation requirements [115]. ...
... The increased interest in the topic of greywater recycling resulted in increased awareness of the risks associated with the use of greywater and the resulting sanitation requirements [115]. An often-discussed aspect of greywater recycling was the financial profitabil- The increased interest in the topic of greywater recycling resulted in increased awareness of the risks associated with the use of greywater and the resulting sanitation requirements [115]. An often-discussed aspect of greywater recycling was the financial profitability of greywater collection and storage facilities [116]. ...
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The use of greywater reduces the consumption of many resources and is an effective tool for achieving Sustainable Development Goals. In order to assess the rationality of its use as an alternative source of energy and water in buildings, a holistic literature review was carried out based on a bibliometric analysis of publications in these fields. The main bibliographic source was the Web of Science database. This review contributed to a better understanding of the analyzed research field. It also revealed trends in greywater energy recovery and recycling research, indicating that these are developing fields. In recent years, there has been a marked increase in the number of publications on the most popular ways of using greywater in buildings, with the territorial scope of research carried out in the greywater recycling domain being considerably larger than research on greywater energy recovery. The analysis revealed poor cooperation between different universities, especially in the field of greywater energy recovery. In light of previous literature reviews, some important research gaps and further proposals for future research were also identified. They concern, in particular, the simultaneous use of greywater as an alternative source of energy and water. Together with the findings of other researchers and people related to the subject matter, this review can contribute to the further development of greywater energy recovery systems and greywater recycling systems.
... In addition to sludge arising after drinking water treatment, the addition of considerable amounts of chemicals can be minimized. The water reuse systems available from stormwater or greywater can be designed cost-effective with proper operation, presenting no hygienic risk or discomfort to the users (Nolde 1995). To use the treated water for household appliances, the treatment and the distribution of treated water should not demand more energy consumption and chemicals in comparison with conventional systems. ...
Chapter
The small and medium river banks are seriously flooded due to high-intensity of rainfall in monsoon seasons. The floods threatened human safety, life and property. This paper presents a process of 1D steady flow analysis used Hydrologic Engineering Center River Analysis System software. The one-dimensional modelling is applied on research Purna River, this river is one of the non-perennial rivers in Gujarat. This work contains flood model in which station, elevation of each cross-section was assessed at a particular section of the study reach. Steady flow analysis and hydraulic design analysis were carried out and after providing slope and discharge (flood event) at particular cross section software will compute the water surface elevation, depth of water and velocity of the water. The result from the research analysis could be used by flood management authorities to mensurate the flood at various cross-section of the study region.KeywordsHEC-RASPurna RiverSteady flow analysis
... The results in Table 1 showed that Grey water average COD level is relatively high 682.5 mg / L in relation to other studies. Nolde [24] measured COD concentration of 450 mg/L in raw Grey water in Netherlands. Also, Hernández et al. [25] reported a Grey water COD concentration of 420 mg/L in Germany. ...
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The concept of grey water treatment systems can reduce freshwater demand and possibly solve a scarcity of freshwater. This study conducted in a grey water collected from villa compartment at north cost in Egypt. The grey water separated from the black water by separating the drainage system. The collected volume of grey water average 1009 liters / day. The proposed model into this study was cheaper than globally used treatment system. The cost of the global treatment system around 1000 U.S.D. The proposed model coast around 400 U.S.D. the proposed model consists of a several treatment stages such as filtration stage, biological treatment stage then final stage is flotation and disinfection process. The sand filter was used as first treatment stage. This process consumed 3 hours. Then the effluent was biologically treated by a gravel filter as second treatment stage. This process consumed 2 hours. A final treatment stage was the floating and disinfection process supplied with a motorized scraper for skimming process to the formed layer of oil, akum and detergents components. The flotation process consumed 2 hours followed by disinfection process using chlorine consuming a contact time of 1 hour. The removal efficiencies varied significantly between the different treatment stages. Each treatment stage had a major effect into specific physiochemical parameters or bacterial parameters or both. The removal percentage were achieved after disinfection process for COD, BOD5, TSS, Turbidity, Total coliform and E. coli were 89.25%, 91.32%, 90.98%, 94.72%, 99.9% and 99.75% respectively. The grey water after the disinfection process were compared to the Egyptian code for reuse of treated wastewater in agriculture. The final measured parameters were less than class (B) which allows to use the treated grey water in nursery plants, fiber crops and roses. Also, it can be used in flushing toilets and showers. The research added a new dimension in the Gray water treatment, is an invention the way for storage that contributes to improving the environmental performance for internal space through using the high-heat capacity of the water where the temperature gaining and losing slowly that help to moderating the temperature in the internal space. Keywords: Grey water – reused - heat capacity of water - environmental performance
... The characteristic of GW is influenced by multiple factors such as lifestyle or the use of specific personal care products and can vary significantly (Shaikh and Ahammed, 2020). On-site treatment of GW at the building scale is a practical and affordable solution to reuse water for non-potable use with a variety of available technical and nature-based treatment solutions (Atanasova et al., 2017;Li et al., 2009;Morandi et al., 2021;Nolde, 2005). In particular the use of water treatment wetlands on green roofs or vertical greenery systems is emerging as a new field of research (Boano et al., 2020;Pradhan et al., 2019;Zraunig et al., 2019). ...
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Water is the key resource in fulfilling the cooling function of plants in urban environments and needs to be supplied reliably and adequately, especially during dry periods. To avoid an unsustainable use of high-quality drinking water for irrigation, the reuse of greywater should be implemented for Green Infrastructure irrigation in the sense of the circular economy. In this study, the influence of greywater irrigation on vitality of two trees species, Tilia cordata and Acer pseudoplatanus, was determined by investigating the effect of irrigation with raw or treated greywater in comparison to municipal tap water. Plant growth parameters were measured, including leaf area, number of leaves, average leaf area and annual growth. In addition, the relative chlorophyll content was determined and image analysis was used to identify vital and necrotic leaf parts. While treatment did not affect growth after one growing season A. pseudoplatanus had significantly higher leaf necrosis (34.8%) when irrigated with raw greywater compared to treated greywater (15.5%) and tap water (5.8%). Relative chlorophyll content of T. cordata irrigated with tap water decreased over time until it was significantly lower (28.5) then the greywater treatments (34.5 and 35). Image analysis of leaves to quantify necrosis proved to be a sensitive method to quantify plant health and showed negative effects earlier than an analysis of growth. Anionic surfactants and electrical conductivity had a significant influence on plant vitality. Therefore, plant selection should take these parameters into account, when planning green infrastructure irrigated with greywater.
... Mesmo mostrando-se como uma alternativa viável para a redução do uso da água potável, como apontam Al-Jayyousi (2004) e Nolde (2005), o alto custo de instalação, assim como os transtornos aos moradores, muitas vezes, tornam o projeto não atrativo, dificultando, assim, sua implantação. ...
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Splitting the up-water reservoir, a cost effect way to decrease cost for grey water re-use in residential buildings? As many buildings counts with its up reservoir split into two cells, was assessed the possibility to commit one just for reuse water, building up the fire water control, and the other for potable water. This cost reduction analysis was technically assessed (within the framework of the applicable legislation), and economically evaluated against a standard project, with an additional reservoir for the re-used water. For the reuse of water, two options were explored: one using grey water only from bathroom shower and sink to feed toilet flushing and other using all grey water to feed toilet flushing, washing machine and cleaning of common areas it was considered for both projects 16 floors building with 4 apartments each floor (Brazilian R-16 profile). Engineering Standards and Legislation were assessed, and a cost analysis was done as well as top building area use for treatment system, engineering costs and impacts during installation phase. It was found that legislation and regulation were no impediment for the project implementation and for first scenario (grey water form bathroom shower and sink) a water costs of 3.89 R$/m³ result in IRR from 5.12% for standard project, and it is increase to 19.28% for reduction cost project (grey water stored in one of cell from upper reservoir), leading NPV from negative to positive. For the second scenario (utilization of all grey water form building), IRR grows from 49.86%, for standard project, to 20.74% for reduction cost project (both with positive NPV).
... Unlike rainwater harvesting, grey water recycling is not dependent on season or variability of rainfall and as such is a continuous and a reliable water resource. Grey water has a relatively low nutrient and pathogenic content and therefore it can be easily treated to a high quality using simple technologies (Erwin, 2005). If the grey water is used as an additional water source, an increased supply for irrigation water can be ensured, which will in turn lead to an increase in agricultural productivity and contribute to food security. ...
Article
This study aimed at determining the effect of laundry greywater on the growth of tomatoes and physical and chemical properties of a sandy loam Perrox in the Eastern province of Rwanda, Kayonza district, Mwiri sector. The experimental design consisted of plots planted with tomatoes (Lepersicon Esculantum) in a randomized complete block design with three replications and four treatments. Treatment 1: Tomatoes irrigated with pure greywater; Treatment 2: Tomatoes irrigated with a mixture of tap water and greywater at 1:1 ratio; Treatment 3: Alternation of greywater and tap water in a consecutive manner; and Treatment 4: only tap water serving as a control. Results showed that the following soil chemical parameters were significantly increased with greywater application: pH, EC, Av P, Na and SAR. Conversely, soil concentration in Mg and Ca significantly decreased with increase in greywater application. With the exception of soil bulk density, other measured physical properties such as soil hydraulic conductivity, aggregate stability and porosity were significantly reduced with greywater application. The highest values for soil hydraulic conductivity, aggregate stability and porosity were found for soil irrigated with tap water which ranged between 1.01 to 2.1 times higher than that of greywater, mixed or alternated with tap water. The alternate application of greywater and tap water did not affect significantly the stem height and weight of tomatoes. We concluded that the absence of positive growth effect of application of greywater was due to low concentration in essential plant nutrients in greywater, and induced adverse effects on soil chemical, physical, and biological properties. However, alternate application of the greywater and tap water preserved approximately the same soil physico-chemical characteristics as with application of tap water. Thus, among the irrigation treatments involving greywater, the latter should be considered as the most environmentally friendly. We propose combination of greywater with various forms of composts as the one of the most promising investigations on the reuse of greywater in irrigation.
... This type of mechanism is called "membrane bioreactors" (MBR) and has been widely tested, with acceptable results for secondary use water without further treatment (Jefferson et al. 2000, Jefferson et al. 2004, Ramona et al. 2004). According to the regulations for reusing Greywater, it must comply with hygienic aesthetic aspects, environmental tolerance, and economic stability (Kyu-Hong et al. 1998, Nolde 2005, Jong et al. 2010). ...
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Advances in microfiltration and ultrafiltration technology for the treatment of greywater are important today because everything surrounding the use and preservation of water is an issue that increases in importance over the decades, and our planet will be seriously affected by the consequences of climate change, making water availability uncertain. Hence, wastewater recycling and its cyclical use have become a major topic in the scientific and engineering communities. The objective of this research is focused on compiling and updating all the advances in wastewater treatment, with emphasis on Greywater, in which components have a lower pollutant load than the rest of wastewater. In addition, microfiltration and ultrafiltration technologies were the technology selected to investigate in this investigation because they have the local potential for a second use of the wastewater before the discharge of contaminated water to the sanitation network. This research was carried out using words related to the exposed topic, such as “microfiltration”, “ultrafiltration”, “cleaning wastewater” and “greywater” in the search for documents in scientific search engines, selecting those that covered the topic and could be used to create this document. The results that were developed in this investigation, indicate that there is no generalized consensus on how to treat this greywater, nor how to qualify it. Additionally, it is important to note that despite the fact that urban greywater treatments have given good results, with the widespread use of bioreactors for this task, and the existence of various treatment alternatives for liquid waste that have shown good price-value ratio, studies related to greywater treatments using porosities are still in the incipient stages.
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Wastewater treatment plants (WWTP) can provide water and nutrients for plant growth for small scale agricultural farming. Cultivation is possible if the parameters in wastewater treatment plants are available within the usable range. The waste treatment plants use wastewater mainly originating from underground, which is less affected by climate change than surface water and can be used for several purposes even during climate change. This chapter aims to assess the characteristics of treated wastewater at waste treatment plants and discuss its possibility to use the water, surrounding space and nutrients for small scale agricultural purposes. We assessed systematically the worldwide open sources works and use selected four wastewater treatment plants data of Kumamoto city of Japan. The previous results and our data analysis of the pollutant load per capita to the plant and pollutant discharge per capita from the plant showed that all plants are efficiently reduced the pollutants loads. Still, there are variations in nitrogen and phosphorous concentration in the final effluent discharge. On that basis, we found that the treated water is useful for agricultural purposes, and moreover, the nitrates and phosphate values released by all plants are adequate to cultivate microalgae.KeywordsWastewater treatment plantPollutant dischargeNutrientsSmall scale agricultureClimate variability
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Greywater (GW) can be separated in different fractions where the kitchen component might be included. Constructed wetland (CW) systems are commonly used for the onsite treatment of GW, and the fraction treated might impact the performance, operation, and maintenance. These aspects are still poorly explored in the literature and are of importance for a proper design and system sustainability. In this study, a multi-stage household-scale CW system composed of a horizontal flow (HF), followed by a vertical flow (VF) unit, was monitored over 1330 days, focusing on different GW fractions and hydraulic and organic loading rates. The biochemical oxygen demand (BOD) was ~50% lower without the kitchen sink component (GWL) in the system inlet, while no drop was observed in the chemical oxygen demand (COD). Treatment with the GWL component caused a sudden drop in the hydraulic loading rate applied at the HF-CW (~114 to 35 mm per day) and the VF-CW (~230 to 70 mm per day). Even when the HF-CW received ~90 gCOD m−2 per day (GW), the multistage system reached a COD removal of 90%. The lower BOD load when treating GWL avoids clogging and decreases the frequency of maintenance. These variables can be used for the optimal design and operation of a CW, contributing with empirical data to CW guidelines in Brazil, and could additionally be expanded for application in other countries with similar climates.