An increasing number of people want to reduce their environmental footprint by using harvested rainwater as a source for drinking water. Moreover, implementing rainwater harvesting (RWH) enables protection against damage caused by increasing precipitation frequency and intensity, which is predicted for Western Europe. In this study, literature data on rainwater quality were reviewed, and based on Dutch climatological data the usable quantity of rainwater in the Netherlands was calculated. For two specific cases, (1) a densely populated city district and (2) a single house in a rural area, the total costs of ownership (TCO) for decentralized drinking water supply from harvested rainwater was calculated, and a life cycle assessment (LCA) was made. For the single house it was found that costs were very high (€60-€110/m ³ ), and the environmental impact would not decrease. For the city district, costs would be comparable to the present costs of centralized drinking water production and supply, but the environmental benefit is negligible (≤1‰). Furthermore, it was found that the amount of rainwater that can be harvested in the city district only covers about 50% of the demand. It was concluded that the application of rainwater harvesting for drinking water production in the Netherlands is not economically feasible.

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Often rainwater harvesting is considered as an important contribution to a more sustainable society. Rainwater is assumed to be clean water, requiring only limited treatment, and it is thought that there is sufficient rainwater available to provide people with drinking water. In order to check these assumptions, we carried out a desk study into the quality and quantity of rainwater. It was found that rainwater is cleaner than surface water, but still may contain contaminants. Especially the microbiological quality of rainwater is a point of concern, and therefore treatment, including disinfection, will be required. Furthermore, it was found that for densely populated areas, like a city district in Amsterdam, the quantity of rainwater that can be harvested from both built and paved surfaces equals only about half the amount that is required for the inhabitants. If rainwater is collected and treated at a neighborhood level, the costs are in the same order of magnitude as for centralized drinking water treatment. However, at the level of a single house costs are significantly higher. As rainwater requires less treatment than e.g. surface water, a small decrease in environmental impact may be realized. @en

Vrijwel alle drinkwaterbedrijven hebben ambities voor een klimaatneutrale bedrijfsvoering. Een aantal drinkwaterbedrijven probeert met opwekking van duurzame energie hun CO2-voetafdruk te verlagen. Een bijzondere manier van energieopwekking is de levering van thermische energie uit drinkwater, kortweg TED. Toepassing van TED moet een positieve milieu-impact hebben en de drinkwaterkwaliteit mag nooit in gevaar komen. Daarom is het voor drinkwaterbedrijven belangrijk om meer inzicht te krijgen in de risico’s van deze technologie. KWR Watercycle Research Institute heeft twee bestaande TED-systemen nader onderzocht op microbiologische risico’s, economisch rendement en milieu-impact (LCA). In dit artikel zijn de resultaten van het onderzoek kort samengevat.@en

Het doel van het DynaFil-project ‘Efficiënte vergisting met dynamische filtratie’ is het substantieel verhogen van de hoeveelheid organische stof die naar de vergisting wordt gestuurd, zodat de biogasproductie en daarmee de energie-efficiëntie van een RWZI toeneemt. Bij dit onderzoek is uitgegaan van een tweetraps ‘AB-systeem’ met dynamische filtratie, in combinatie met een anaerobe vergister met dynamisch membraan. In dit artikel is vooral gekeken hoe de A-trap kan worden geoptimaliseerd. Een korte contacttijd (15 min.), korte slibleeftijd (0,3 dagen), ijzerdosering en voldoende beluchting blijken een aanzienlijke verbetering op te leveren.@en

The concentration of sulphate present in wastewater can vary from 10 to 500 mg SO₄ ²⁻/L. During anaerobic conditions, sulphate is reduced to sulphide by sulphate-reducing bacteria (SRB). Sulphide generation is undesired in wastewater treatment plants (WWTPs). Previous research indicated that SRB are inhibited by the presence of electron acceptors (such as O₂, NO₃ and NO₂). However, the contact times and concentrations used in those studies are by far higher than occur in WWTPs. Since sulphide can influence the biological nitrogen and phosphorus removal processes, this research aimed to understand how the different electron acceptors commonly present in biological nutrient removal (BNR) systems can affect the proliferation of SRB. For this purpose, a culture of SRB was enriched in a sequencing batch reactor (approx. 88% of the total bacteria population). Once enriched, the SRB were exposed for 2 h to typical concentrations of electron acceptors like those observed in BNR systems. Their activity was assessed using three different types of electron donors (acetate, propionate and lactate). Oxygen was the most inhibiting electron acceptor regardless the carbon source used. After exposure to oxygen and when feeding acetate, an inactivation time in the sulphate reduction activity was observed for 1.75 h. Once the sulphate reduction activity resumed, only 60% of the original activity was recovered. It is suggested that the proliferation of SRB is most likely to occur in BNR plants with an anaerobic fraction higher than 15% and operating at sludge retention times higher than 20 days (at a temperature of 20 °C). These results can be used to implement strategies to control the growth of sulphate reducers that might compete for organic carbon with phosphate-accumulating organisms.

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