High population growth, increasing urbanization and rapid economic development are exerting pressure on the already scarce water resources in India. Treatment and reuse of wastewater can play an important role in addressing some of the urban water challenges. Conventional treatment plants have many challenges, therefore, natural treatment systems (NTSs) are viewed as a cost-effective alternative, which are more suitable in the Indian context. This study builds on a desktop study of NTSs and presents a rapid sustainability assessment of 12 NTSs, highlighting the potential and viability of NTSs in India. The results show that the NTSs have a high potential for wastewater treatment. However, there are still gaps in knowledge related to aspects that hinder the sustainability of the systems. Risks associated with reuse of treated wastewater in agriculture, operational problems and social acceptance were perceived as frequent challenges. Self-sustaining financing methods and the use of by-products were viewed as added benefits
ZusammenfassungDie Korn- und Stroherträge, der Energie-Input (Kraftstoff, Mineraldünger, Pflanzenschutzmittel, Maschinen) und die Kennzahlen zur Energieeffizienz (Energie-Output, Netto-Energie-Output, Energieintensität, Energienutzungseffizienz) in Abhängigkeit der mineralischen Stickstoffdüngermenge (0 kg, 60 kg, 120 kg und 180 kg N ha−1) und der Düngerstrategie (unterschiedliche Mineraldüngerformen und Gabenteilungen) wurden auf zwei Standorten im Marchfeld (Engelhartstetten und Groß-Enzersdorf) auf Basis von zwei zweijährigen Feldversuchen analysiert. Dabei sollte die Frage beantwortet werden, welche mineralische N-Düngung (N-Form, N-Menge und Splittung der N-Menge) die höchste Energieeffizienz aufweist. Mit zunehmender mineralischer N-Menge (60 kg, 120 kg bzw. 180 kg N ha−1) nahm der energetische Anteil des Mineraldüngers am Gesamtenergie-Input um 24 %, 38 % bzw. 48 % zu. Durch das Gesetz des abnehmenden Ertragszuwachses wurde in Engelhartstetten bei einer N-Düngermenge von 180 kg N ha−1 eine signifikant verringerte Energieeffizienz im Vergleich zu 60 kg N ha−1 und 120 kg N ha−1 festgestellt. Eine Aufteilung der N-Düngermenge auf drei Gaben erhöhte den Kraftstoffverbrauch um 4 % gegenüber einer einmaligen Applikation der gesamten Düngermenge. Die Kennzahlen der Energieeffizienz wurden durch die Gabenteilung kaum beeinflusst. Die N-Düngung mit Kalkammonsalpeter war energieeffizienter als die Harnstoffdüngung (rein, stabilisiert, eingearbeitet). Die Energieeffizienzanalyse kann somit einen wertvollen Beitrag leisten, um pflanzenbauliche Maßnahmen hinsichtlich ihren Umweltauswirkungen zu bewerten.
Often centralized water supply, sanitation and solid waste services struggle to keep up with the rapid expansion of urban areas. The peri-urban areas are at the forefront of this expansion and it is here where decentralized technologies are increasingly being implemented. The introduction of decentralized technologies allows for the development of new opportunities that enable the recovery and reuse of resources in the form of water, nutrients and energy. This resource-oriented management of water, nutrients and energy requires a sustainable system aimed at low resource use and high recovery and reuse rates. Instead of investigating each sector separately, as has been traditionally done, this article proposes and discusses a concept that seeks to combine the in-and outflows of the different sectors, reusing water and other liberated resources where possible. This paper shows and demonstrates examples of different types of sustainable technologies that can be implemented in the peri-urban areas of Mexico City [rainwater harvesting, EcoSan and OPEN ACCESSWater 2012, 4 740 biofiltros (small constructed wetlands), and (vermi-)composting]. An innovative participatory planning method, combining scenario development with a participatory planning workshop with key stakeholders, was applied and resulted in three concept scenarios. Specific technologies were then selected for each concept scenario that the technical feasibility and applicability was assessed. Following this, the resulting resource flows (nutrients, water and energy) were determined and analyzed. The results show that decentralized technologies not only have the potential to deliver adequate water supply, sanitation and solid waste services in peri-urban areas and lessen environmental pollution, but also can recover significant amounts of resources thereby saving costs and providing valuable inputs in, for instance, the agricultural sector. Social acceptance of the technologies and institutional cooperation, however, is key for successful implementation.
This paper presents the results of a collaborative work with farmers and a cost-benefit analysis of geospatial technologies applied to irrigation water management in a semi-arid agricultural area in Lower Austria. We use Earth observation (EO) data to estimate crop evapotranspiration (ET) and webGIS technologies to deliver maps and irrigation advice to farmers. The study reports the technical and qualitative evaluation performed during a demonstration phase in 2013 and provides an outlook to future developments. The calculation of the benefits is based on a comparison of the irrigation volumes estimated from satellite vs. the irrigation supplied by the farmers. In most cases, the amount of water supplied was equal to the maximum amount of water required by crops. At the same time high variability was observed for the different irrigation units and crop types. Our data clearly indicates that economic benefits could be achieved by reducing irrigation volumes, especially for water-intensive crops. Regarding the qualitative evaluation, most of the farmers expressed a very positive interest in the provided information. In particular, information related to crop ET was appreciated as this helps to make better informed decisions on irrigation. The majority of farmers (54%) also expressed a general willingness to pay, either directly or via cost sharing, for such a service. Based on different cost scenarios, we calculated the cost of the service. Considering 20,000 ha regularly irrigated land, the advisory service would cost between 2.5 and 4.3 e/ha per year depending on the type of satellite data used. For comparison, irrigation costs range between 400 and 1000 e/ha per year for a typical irrigation volume of 2000 cubic meters per ha. With a correct irrigation application, more than 10% of the water and energy could be saved in water-intensive crops, which is equivalent to an economic benefit of 40-100 e/ha per year.
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