An integrated assessment of options for rural wastewater management in Austria

M. Starkl, M. Ornetzeder, E. Binner, P. Holubar, M. Pollak, M. Dorninger, F. Mascher, M. Fuerhacker and R. Haberl;Water Science & Technology, 56 (2007): 5, 105-113This paper reports a recently finished, interdisciplinary project on rural wastewater management in Austria. The objective of the project was to study alternative wastewater management options based on separation of the wastewater into its constituent parts, and to compare them with conventional ones. Thereby, a feasibility study of both conventional and alternative options for wastewater management in six model regions was carried out. Life cycle costs and social acceptance were analysed by using a case study-based assessment approach. However, hygienic and environmental risks were evaluated on a more general level. In order to complement the findings, a survey on urine separation system users in the Solar City of Linz was conducted. Based on these assessments and empirical findings, the paper concludes that options using a full separation of all wastewater fractions should be considered with care. Options based on a separation of only grey water and black water or in the liquid/solid phase can offer ecological and financial advantages over conventional options. Further, options combining wastewater management and regional biogas plants were identified as an interesting solution. However, legal constraints restrict this option currently

Solar photo-Fenton treatment—Process parameters and process control

Photo-Fenton experiments were performed using alachlor as a model compound (initial concentration 100 mg/L) in a compound parabolic collector solar pilot-plant. Three process parameters were varied following a central composite design without star points (temperature 20–50 °C, iron concentration 2–20 mg/L, illuminated volume 11.9–59.5% of total). Under all experimental conditions, complete alachlor degradation, mineralisation of chloride and 85–95% mineralisation of dissolved organic carbon (DOC) was achieved. An increase in temperature, iron concentration and illuminated volume from minimum to maximum value reduced the time required for 80% degradation of initial DOC by approximate factors of 5, 6 and 2, respectively. When process parameter changes were made simultaneously, these factors multiplied each other, resulting in degradation times between 20 and 1250 min. Models were designed to predict the time necessary to degrade 50 or 80% of the initial DOC applying response surface methodology (RSM). Another model based on the logistic dose response curve was also designed, which predicted the whole DOC degradation curve over time very well. The three varied process parameters (temperature, iron concentration and illuminated volume) were independent variables in all the models. Mass balances of hydrogen peroxide consumption showed that the same amount of hydrogen peroxide was always needed to degrade a certain amount of DOC regardless of variations in the process parameters within the range applied. Possible applications of the models developed for automatic process control are discusse