Urban wastewater systems: From disposal to reuse. A study of different systems with focus on water and nutrients flows.

Urban wastewater systems are currently exposed to a major rethink dictated by new demands on resource management. It is postulated that next to providing efficient sanitation (preventing spread of pathogenic microorganisms) these systems should support resource reuse. It remains uncertain of what will be the sanitation of the future; the understanding of technical performances of various alternatives towards possibilities to improve resource management is a necessary background for choosing design alternatives of wastewater systems to be used in the future. This thesis consists of a number of studies all with an aim to better understand the performance of the current and alternative urban wastewater systems as applied in industrialized countries and their influence on the environment. The objective is to quantify the differences in performance of existing (conventional and alternative) as well as other possible systems. Technical performances of wastewater systems are quantified mainly with respect to nutrients and water flow. Waste/resource reuse possibilities and interaction with existing infrastructure is also investigated. The alternative systems studied are mainly urine separation systems and extensive vegetated roofs for storm water retention and disposal. The interconnection and inter-influence of urban wastewater systems with other technical and non-technical systems/sectors of society is also investigated, which is done in both a conceptual and quantitative way. The results prove the potential of a change in urban wastewater management towards source control and reuse. Wastewater systems based on source control can potentially support water savings, water reuse and nutrients reuse. When the alternative systems are implemented on a small scale only, their influence on the environment (positive or negative) is negligible; however the effects will be more and more significant as more and more systems coming into operation. The results from the studies performed in this thesis showed that to achieve desired changes, technical developments of new systems are crucial, but there is also a need of institutional adjustments to support novel systems with legal and economic means

Experiences from the implementation of a urine separation system: Goals, planning, reality

Over the last decade it has been ever increasing interest in developing alternative sanitary systems, which would be more sustainable than a conventional one is. In Sweden urine separation has been considered a promising approach towards increasing recycling of wastewater nutrients. Full scale trials are carried out and examined. This paper presents a study on implementation of urine separation system in urban environment. Technical and non-technical aspects of system performance are evaluated; system's interference with existing infrastructure is examined. Benefits and losses connected to urine separation system are analysed not only from environmental perspective but also system's owner point of view. (C) 2005 Elsevier Ltd. All rights reserved

Storm water quality of first flush urban runoff in relation to different traffic characteristics

Storm water quality was monitored at four sites in a middle-sized Swedish town. The objective was to compare storm water pollution in the first flush storm water runoff between sites with different traffic intensities within a town. Flow proportional storm water runoff samples were collected. The samples were analyzed for suspended solids, conductivity, total nitrogen, total phosphorus, oil index, lead, cadmium, copper, chromium, nickel, and zinc.The results showed that the levels of heavy metals and total phosphorus in storm water were highest at the site with the highest traffic intensity (7000 vehicles/day). A strong linear dependence between suspended solids (SS) and total phosphorus and heavy metals was observed. SS was the dominant explanatory variable for these parameters and a suitable predictor. The observed correlation between SS, heavy metals, and total phosphorus means that reducing levels of suspended solids in storm water would contribute to a substantial decrease of particle-bound heavy metals and total phosphorus in storm water. No samples were taken during winter; however, results indicate that de-icing material used in winter may affect surface runoff quality during other seasons. The results can be used as a reference for storm water quality management for traffic-related sites in towns with similar land use and climatic characteristics

Green roof performance towards management of runoff water quantity and quality: A review

This review paper addresses the role of green roofs in urban drainage considering both management of water quantity and quality. Results from investigation of full scale installations as well as from laboratory models are reviewed. The following factors affecting runoff dynamics from green roofs are discussed: type of green roof and its geometrical properties (slope): soil moisture characteristics: season, weather and rainfall characteristics; age of green roof; vegetation. Design parameters as suggested by different authors are also reviewed. Factors which affect influence of a green roof on runoff water quality are discussed in general terms followed by the review of data regarding concentrations of phosphorus, nitrogen, and heavy metals in green roof runoff, its' pH. and first flush effect. Linking among fertilization, runoff pollution and vegetation development is given a particular focus. The review indicates clearly that there is a need for more research into a green roof performance in an urban environment. The differences measured by few existing studies between the early years performance of green roofs and the later years indicate a need for long term monitoring of green roofs. (C) 2010 Elsevier B.V. All rights reserved

The influence of extensive vegetated roofs on runoff water pollution load

The influence of extensive sedum-moss vegetated roofs on runoff water pollution loads was studied for four full scale installations located in southern Sweden. The aim of the study was to ascertain whether the vegetated roof behaves as a sink or a source of pollutants on annual basis. The pollution loads from vegetated roofs was also compared with the pollution loads from two non-vegetated roofs located in the study areas. The annual pollution loads were calculated based on the measured water quality and the volumes of annual precipitation and the annual roof runoff. Concentrations were measured during four precipitation events in November-December 2003. The following metals and nutrients were investigated: Cd, Cr, Cu, Fe, K, Mn, Pb, Zn, NO3-N, Tot-N, PO4-P, and Tot-P. The results show that, on the annual basis when total loads are considered, vegetated roofs behave as sink of nitrogen and source of potassium and phosphorus, the last with the exception of the oldest vegetated roof. The influence of vegetated roofs on annual heavy metals loads in runoff is less significant

Stadens inverkan på vattenmiljön i avrinningsområden

The influence of the city on the water environment on river basin scale is discussed with mainly the Höje River as an example. The city significantly influence the phosphorous and heavy metal conditions if the city is larger than about 100 000 people in an agricultural river basin smaller than 300 km2