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Ochre, waste iron sludge from the treatment of iron rich groundwater for potable use, makes up a significant waste problem. Furthermore, wastewater treatment plants with enhanced biological phosphorus removal and the digestion of sludge are in lack of iron for the prevention of hydrogen sulfide production and the release of phosphorous during anaerobic digestion. Thus, the addition of ochre to anaerobic digestion is a potential beneficial reuse of ochre. Sludge from wastewater treatment plants with enhanced biological phosphorus removal was used for the experiments. Batch and continuous pilot-scale tests were performed for the mesophilic digestion of primary and waste-activated sludge with different doses of ochre. Two different doses of ochre corresponding to molar ratios of 1 and 2 moles Fe3+/mole P released in the batch test resulted in 29% and 57% reductions of phosphates respectively in the sludge liquor compared to the control sludge without inhibiting the digestion process. In the pilot experiment, the dosing of ochre at both a high and low dose (molar ratios of 1.6 and 0.8 Fe3+/S2&minus, respectively ) resulted in an immediate drop in the H2S concentration (from &gt, 2000 ppm down to 570 ppm), while the control reactor still produced biogas with a high hydrogen sulfide concentration. The inhibition of the digestion process was observed (accumulation of acetate) at the higher dose. In a second pilot scale experiment, lower doses of ochre were tested continuously (1.5 and 0.75 mole Fe3+/mole Preleased) to avoid any inhibition, while evaluating the phosphate precipitation. A reduction of phosphates in sludge liquor (33% and 66% for the low and high doses respectively) was obtained.

Source separation and decentralised treatment of domestic wastewaters for resource recovery have matured into a viable alternative for large-scale centralised treatment. The separate collection of toilet wastewater facilitates optimised treatment of the separate flows for efficient resource recovery. Practical examples are set at the four demonstration sites of EU-project Run4Life. 5 Socio-economical and legislative aspects are important in the applicability of these concepts and recovered products, as well as hygienic safety, heavy metals and organic micropollutants. Depending on site-specific issues, different technologies can be integrated to recover products that meet the requirements of agriculture and society.

Domestic wastewater (WW) is an important carrier of nutrients usually wasted away by current centralised sewage treatment plants. The Run4Life project proposes an alternative strategy for increasing circularity of WW treatment systems and improving nutrient recovery rates and material qualities. This is based on a decentralised treatment of segregated black water (BW), kitchen waste and grey water combining existing and innovative technologies.Run4Life is currently improving innovative nutrient recovery technologies, these being: (i) an ultra-low flush vacuum toilet, which uses around 0.5L/flush, thus less water than conventional vacuum toilets, allowing concentration of BW compared to conventional toilets and vacuum toilets. (ii) Bio-electrochemical systems for nitrogen recovery, which recovers up to 12.8 g/m2*d of Nitrogen present in blackwater as liquid fertilizer (ammonium nitrate) iii) (Hyper-)thermophilic anaerobic digestion, which aims to recover the phosphorous and nitrogen in the hygienised effluent in a one-step treatment and ready for use as fertilisers. Nutrient recycling technologies from domestic WW are demonstrated at large scale in four demonstration sites where decentralised WW treatment systems are implemented: Ghent (Belgium, 430 houses), Helsingborg (Sweden, 320 apartments), Sneek (The Netherlands, 32 houses), and Vigo (Spain, 1 office building). This will result in solid and liquid NPK fertilizers being recovered in the form of struvite, ammonium nitrate, calcium phosphate, organic fertilizers and reclaimed water.The environmental, economic and societal impact of the obtained fertilizers is being tested by means of ecotoxicology tests, pot experiments, field trials, and by a selection of key performance indicators based on European, national and regional legislation present in the four different countries. Life cycle assessments are being performed for each technology and demonstration site, and active measures such as knowledge brokerage activities are being developed as an engagement strategy to advocate the institutional, legal and social acceptance of the Run4Life nutrient recovery technologies and fertilizers produced. In addition, new business models which can benefit from the Run4Life project are currently being assessed.It is expected that, by the end of the project, more than 90% of the water will be reused, and that nutrient recovery rates will achieve 100%.

Urban source separation infrastructure systems have a promising potential for a more sustainable management of household food waste and wastewaters. A renewed trend of larger implementations of pilot areas with such systems is currently emerging in Northern Europe. This study investigates the drivers behind the decision of stakeholders to implement source separation systems as well as the importance of the previously existing pilot areas in the decision-making process. By means of semi-structured expert interviews, five areas with source separation were characterized and compared. It was found that the most important drivers were on the one hand governmental, especially local environmental goals and on the other hand the ambition of the utilities to gain knowledge about future wastewater management and treatment technologies. Experiences from existing smaller pilot areas were shown crucial for decisions to implement the larger pilot areas that are currently planned, as was intensive stakeholder co-operation, due to the fact that source separation systems transcend traditional boundaries between energy, waste and water sectors. The results hold implications for policy makers and municipalities initiating a transition to more sustainable wastewater management.

The application of treated sewage sludge on farmland is a suggested method for recycling nutrients and reducing demand for commercial fertilizer. However, sludge needs to be safe from possible contaminants which can cause acute and long-term health and environmental problems. Residual pharmaceuticals and organic contaminants are mentioned as emerging threats since wastewater treatment plants are not designed to degrade these substances. The aim of this study was to screen and evaluate the presence, and reduction, of pharmaceuticals and polycyclic aromatic hydrocarbons (PAHs) during anaerobic digestion of mixed primary and waste-activated sludge at 35, 55 and 60 °C and during pasteurization at 70 °C. The study showed the difficulty of analysing pharmaceutical compounds in low concentrations in the sludge matrix. No general reduction of these compounds was seen during treatment, but for individual substances some reduction occured. The PAHs were generally not reduced during digestion or pasteurization, but for three substances (indeno[1,2,3-cd]pyrene and dibenzo[a,h]anthracene (analysed together) and benzo[g,h,i]perylene) reduction (up to 60%) during digestion was seen. Digestion at 35 and 55 °C resulted in about the same order of reduction of the three individual PAHs, which was higher than for digestion at 60 °C.

Source separation systems for the management of domestic wastewater and food waste has been suggested as more sustainable sanitation systems for urban areas. The present study used an attributional life cycle assessment to investigate the carbon footprint and potential for nutrient recovery of two sanitation systems for a hypothetical urban area in Southern Sweden. The systems represented a typical Swedish conventional system and a possible source separation system with increased nutrient recovery. The assessment included the management chain from household collection, transport, treatment and final return of nutrients to agriculture or disposal of the residuals. The results for carbon footprint and nutrient recovery (phosphorus and nitrogen) concluded that the source separation system could increase nutrient recovery (0.30–0.38 kg P capita−1 year−1 and 3.10–3.28 kg N capita−1 year−1), while decreasing the carbon footprint (−24 to −58 kg CO2-eq. capita−1 year−1), compared to the conventional system. The nutrient recovery was increased by the use of struvite precipitation and ammonium stripping at the wastewater treatment plant. The carbon footprint decreased, mainly due to the increased biogas production, increased replacement of mineral fertilizer in agriculture and less emissions of nitrous oxide from wastewater treatment. In conclusion, the study showed that source separation systems could potentially be used to increase nutrient recovery from urban areas, while decreasing the climate impact.

High-volume, low-strength industrial wastewaters constitute a large potential for biogas production, which could be realized by membrane bioreactors operating at the ambient temperature of the wastewater. However, the start-up of low-temperature anaerobic processes using unadapted inoculum can be sensitive to overloading, which results in acidification. This study assessed if a novel acidification limit test can be used to identify stable organic loading rates as well as process over-loading. The test is based on easy-to-apply batch experiments for determination of the hydrolysis rate constant and the specific methanogenic activity of the acetotrophic and hydrogenotrophic pathways. For evaluation, two anaerobic membrane bioreactors, treating synthetic dairy wastewater at an ambient temperature of 24 °C, were used with a slow or a rapid start-up regime, respectively. Tests for hydrolysis rate and methanogenic activity were performed throughout the experiment and were used to calculate acidification limits for each system throughout the start-up. The acidification limit test was able to successfully identify both stable operation of one reactor and process failure of the other reactor as the organic loading rate increased. The reactor failure was caused by over-loading the acetotrophic pathway and coincided with microbial changes observed in real-time PCR and moving window analysis. Overall, the acidification limit tests seem promising as an easy applicable method for estimating what organic loading rate can be utilized, without risking acidification of anaerobic systems.

Hydrolysis constants of mixed sludge at 35°C, 55°C, and 60°C were found to be 0.32 d-1, 0.44 d-1, and 0.50 d-1, respectively in pilot-scale semi-continuously operated anaerobic digesters. The hydrolysis constants as well as estimated chemical oxygen demand (COD) fractions in the feed were introduced to a mathematical model for anaerobic digestion published by Siegrist et al. (2002) which is similar to Anaerobic Digestion Model No. 1 (ADM1). First-order and Monod-type kinetics were tested for estimation of hydrolysis constants. The applied kinetics were found to affect the outcome of the regression study. Moreover, the free ammonia inhibition model was excluded for both propionate oxidation and acetate conversion, thanks to the apparent acclimatized biomass. No substantial accumulation of volatile fatty-acids (VFA) was observed in the reactors at 35, 55 and 60°C corresponding to free ammonia nitrogen (FAN) concentrations of about 20, 110 and 130 g N/m3, respectively. (Less)

In the last decades, the focus on waste and wastewater treatment systems has shifted towards increased recovery of energy and nutrients. Separation of urban food waste (FW) and domestic wastewaters using source control systems could aid this increase; however, their effect on overall sustainability is unknown. To obtain indicators for sustainability assessments, five urban systems for collection, transport, treatment and nutrient recovery from blackwater, greywater and FW were investigated using data from implementations in Sweden or northern Europe. The systems were evaluated against their potential for biogas production and nutrient recovery by the use of mass balances for organic material, nutrients and metals over the system components. The resulting indicators are presented in units suitable for use in future sustainability studies or life-cycle assessment of urban waste and wastewater systems. The indicators show that source control systems have the potential to increase biogas production by more than 70% compared with a conventional system and give a high recovery of phosphorus and nitrogen as biofertilizer. The total potential increase in gross energy equivalence for source control systems was 20-100%; the greatest increase shown is for vacuum-based systems.

Legislation in Sweden and the European Union concerning the use of sewage sludge in agriculture is under revision and future concentration limits for pathogens in treated sludge are likely to be expected. The aim of this study was to evaluate the hygienization of Salmonella, Escherichia coli, Enterococcus and Clostridium perfringens through continuous anaerobic digestion at 35, 55 or 60 °C, as well as to investigate process stability and methane production at 60 °C. The results indicated that digestion at 55 or 60 °C with a minimum exposure time of 2 h resulted in good reduction of Salmonella, E. coli and Enterococcus and that anaerobic digestion could thus be used to reach the concentration limits suggested for the EU, as well as Sweden. Furthermore, stable continuous anaerobic digestion of sludge was achieved at 60 °C, albeit with 10% less methane production compared to digestion at 35 and 55 °C.

The large volume of industrial low-strength wastewaters has a potential for biogas production through conventional anaerobic digestion (AD), limited though by the need of heating and concentrating of the wastewaters. The use of anaerobic membrane bioreactor (AnMBR) combining membrane filtration with anaerobic biological treatment at low temperature could not only reduce the operational cost of AD, but also alleviate environmental problems. However, at low temperature the AnMBR may suffer more fouling due to the increased extracellular polymeric substances production excreted by bacteria hampering the application of the process for the industrial wastewater treatment. In order to solve or reduce the fouling problem it is necessary to have a good insight into the processes that take place both on and in the membrane pores during filtration. Therefore, the objective of this study is to contribute to a better understanding of organic and biofouling in AnMBR. An AnMBR consisting of external PVDF membrane was operated at 25°C and fed with synthetic dairy wastewater. Intensity, morphology and composition of foulants were determined using Scanning Electron Microscopy coupled with X-ray Energy Dispersive Spectrometry (EDS), Fourier Transform Infrared Spectrometry (ATR-FTIR), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), Ion chromatography (IC), zeta potential, and adenosine triphosphate measurements. Based on membrane autopsies, it can be concluded that prevailing fouling is mainly of biological and organic origin. SEM observations demonstrated presence of numerous bacteria incorporated with the fouling layer composed of mainly proteins, carbohydrates and lipids as revealed by ATR-FTIR measurements. Furthermore the amounts of ions found by EDS & ICP-OES analysis do not support scaling layer formation.