Daniel Hellström

A Framework for Systems Analysis of Sustainable Urban Water Management

Abstract The increasing demand for sustainable development will have a profound impact on all types of urban infrastructures. However, there is a lack of knowledge of how sustainable development should be attained and how sustainability of various technical systems should be assessed. This paper describes the framework of a systems analysis project dealing with the above issues, which focuses on urban water and wastewater systems. The project is part of large national research program in Sweden entitled “Sustainable Urban Water Management.” A set of sustainability criteria—covering health and hygiene, social and cultural aspects, environmental aspects, economy and technical considerations—are defined. To promote the practical use of a set of sustainability criteria it must be concise and related to quantifiable indicators that are easily measured. This paper suggests suitable indicators for the proposed criteria. It also contains a brief analysis of the contribution to various environmental effects and resource utilization of the Swedish urban water system in relation to the impact of Swedish society in total, to allow for a correct prioritization of the criteria.

Storage of human urine: acidification as a method to inhibit decomposition of urea

Abstract One strategy to increase the recycling ratio of nutrients from wastewater to agriculture is to handle urine separately and use it as a fertiliser in agriculture. Potential drawbacks to urine handling systems are the risk of ammonia evaporation and the relatively large volumes to be handled. The amount of urine solution could be reduced by using drying techniques if ammonia evaporation could be avoided. The objective of this project was to study how different acids could be used to prevent the decomposition of urea into ammonia during storage. The project was performed in two phases. The initial phase was conducted with one time dosage of urine in bottles of 0.5 l each to evaluate the effect of different storage conditions and to estimate suitable amounts of acids to be added. The second phase was conducted with multi-time dosages of urine, simulating the continuous addition of urine found in full-scale systems, in plastic cans of 10 l each. The results show that a one-time dosage of 60 meq sulphuric or acetic acid per litre undiluted urine at the beginning of the storage period could inhibit the decomposition of urea during more than 100 days of storage in cans with multi-time dosages of urine.

Comparison of environmental effects and resource consumption for different wastewater and organic waste management systems in a new city area in Sweden

An analysis of the environmental effects and resource consumption by four systems for management of wastewater and organic household waste in a new city area have been performed, as follows: (1) conventional system complemented with advanced sludge treatment for phosphorus recovery, (2) blackwater system with urine diversion and food waste disposers, (3) blackwater system with food waste disposers and reverse osmosis, and (4) local wastewater treatment plant with nutrient recovery by using reverse osmosis. Substance-flow analysis and energy/exergy calculations were performed by using the software tool URWARE/ORWARE. Emissions were calculated and classified based on the impact categories global warming potential, acidification, and eutrophication, according to ISO 14042 (2000). The analysis also included nutrient recovery (i.e., the potential to use nutrients as a fertilizer). Depending on which aspects are prioritized, different systems can be considered to be the most advantageous.

Evaluation of small on‐site wastewater treatment systems

Purpose – The purpose of the project was to evaluate and demonstrate new solutions for decreasing the discharges from on‐site wastewater treatment plants.Design/methodology/approach – The study evaluated several on‐site wastewater treatment plants. Seven of the investigated facilities were package plants, two were urine separating plants with large sand filters, two had storage tanks to collect wastewater separated from toilets and compact sand filters, and, finally, four had chemical precipitation in combination with large sand filters.Findings – All of the systems have shown that they are able to remove more than 90 per cent of the phosphorus and more than 90 per cent of the organic matter. The sorting systems also give very low local emissions of nitrogen. To guarantee that the package plants perform well and manage to fulfil high reduction demands, there is a need for well functioning organisations for supervision and operation. The source separating systems require well‐informed and motivated users t...

Exergy Analysis: A Comparison of Various Treatment Alternatives for Nutrient Removal

There is an increasing interest for more sustainable sewerage systems. An important tool in the analysis of the sustainability of a sewerage system is exergy analysis. It is possible, by using an exergy analysis, to estimate the consumption of physical resources. The objective of this paper is to compare different methods for nutrient removal by using exergy analysis. Flows included in the analysis are those that are related to the treatment processes for separation of organic matter, nitrogen and phosphorus. The treatment alternatives considered in this analysis are different processes with biological nitrogen and phosphorus removal and different processes combining biological nitrogen removal and chemical phosphorus removal. Further, the effect of source separation of urine was considered. If nitrogen removal is considered to be important, the results show that installation of urine separation toilets may be an interesting alternative to biological nitrogen removal. If only the exergy consumption due to operation is considered it seems to be preferable to combine urine separation with chemical phosphorus removal.

Klosettvattensystem : Nordisk inventering och förslag till FoU

Genom att samla upp klosettvatten skiljt fran BDT-vattnet (bad/disk/tvatt) kan huvuddelen av hushallsavloppsvattnets naringsamnen samlas upp, med ett minimum av fororeningar. Inom ramen for detta p ...