Assessment of environmental impacts and operational costs of the implementation of an innovative source-separated urine treatment.

Innovative treatment technologies and management methods are necessary to valorise the constituents of wastewater, in particular nutrients from urine (highly concentrated and can have significant impacts related to artificial fertilizer production). The FP7 project, ValuefromUrine, proposed a new two-step process (called VFU) based on struvite precipitation and microbial electrolysis cell (MEC) to recover ammonia, which is further transformed into ammonium sulphate. The environmental and economic impacts of its prospective implementation in the Netherlands were evaluated based on life cycle assessment (LCA) methodology and operational costs. In order to tackle the lack of stable data from the pilot plant and the complex effects on wastewater treatment plant (WWTP), process simulation was coupled with LCA and costs assessment using the Python programming language. Additionally, particular attention was given to the propagation and analysis of inputs uncertainties. Five scenarios of VFU implementation were compared to the conventional treatment of 1 m3 of wastewater. Inventory data were obtained from SUMO software for the WWTP operation. LCA was based on Brightway2 software (using ecoinvent database and ReCiPe method). The results, based on 500 iterations sampled from inputs distributions (foreground parameters, ecoinvent background data and market prices), showed a significant advantage of VFU technology, both at a small and decentralized scale and at a large and centralized scale (95% confidence intervals not including zero values). The benefits mainly concern the production of fertilizers, the decreased efforts at the WWTP, the water savings from toilets flushing, as well as the lower infrastructure volumes if the WWTP is redesigned (in case of significant reduction of nutrients load in wastewater). The modelling approach, which could be applied to other case studies, improves the representativeness and the interpretation of results (e.g. complex relationships, global sensitivity analysis) but requires additional efforts (computing and engineering knowledge, longer calculation time). Finally, the sustainability assessment should be refined in the future with the development of the technology at larger scale to update these preliminary conclusions before its commercialization.

Development of USEtox characterisation factors for dishwasher detergents using data made available under REACH.

Because of the more and more stringent regulations and customer demand, dishwasher detergent manufacturers are constantly improving the composition of the products towards better environmental performances. In order to quantify the pros and cons of these changes on the lifecycle of detergents, as compared to conventional products, the use of Life Cycle Assessment (LCA) is a meaningful opportunity. However, the application of the methodology is hampered by the lack of Characterisation Factors (CFs) relative to the specific chemical substances included in the detergents composition, which cannot be included in the impact assessment of the effluent discharge. In this study we have tackled this problem, taking advantage of the specific case of three dishwasher detergents produced by the Chemolux/McBride group: phosphate-based, eco-labelled and phosphate-free formulations. Nine CFs for freshwater ecotoxicity and seven CFs for human toxicity have been developed, using the USEtox methodology and data made available under the REACH regulation. As a result, the dishwasher effluent composition could be characterised by more than 95% for freshwater ecotoxicity whereas for human toxicity the percentage was less than 36%, due to the lack of adequate and reliable repeated dose toxicity studies. The main contributing substances to freshwater ecotoxicity were found to be sodium percarbonate and sodium triphosphate, the latter confirming the pertinence of phosphates banning in the detergent industry. Regarding human toxicity, zinc shows the highest contribution. Further comparison to previous studies and sensitivity analysis substantiated the robustness of these conclusions.

Comparative and integrative environmental assessment of advanced wastewater treatment processes based on an average removal of pharmaceuticals.

Pharmaceuticals are normally barely removed by conventional wastewater treatments. Advanced technologies as a post-treatment, could prevent these pollutants reaching the environment and could be included in a centralized treatment plant or, alternatively, at the primary point source, e.g. hospitals. In this study, the environmental impacts of different options, as a function of several advanced treatments as well as the centralized/decentralized implementation options, have been evaluated using Life Cycle Assessment (LCA) methodology. In previous publications, the characterization of the toxicity of pharmaceuticals within LCA suffers from high uncertainties. In our study, LCA was therefore only used to quantify the generated impacts (electricity, chemicals, etc.) of different treatment scenarios. These impacts are then weighted by the average removal rate of pharmaceuticals using a new Eco-efficiency Indicator EFI. This new way of comparing the scenarios shows significant advantages of upgrading a centralized plant with ozonation as the post-treatment. The decentralized treatment option reveals no significant improvement on the avoided environmental impact, due to the comparatively small pollutant load coming from the hospital and the uncertainties in the average removal of the decentralized scenarios. When comparing the post-treatment technologies, UV radiation has a lower performance than both ozonation and activated carbon adsorption.

Cost-performance indicator for comparative environmental assessment of water treatment plants.

To compare potable water production plants on the basis of the environmental impacts generated by the treatment, including water resource depletion, Life Cycle Assessment (LCA) methodology is often used as referential. A comparison based only on the environmental impacts can however be misleading. Criteria for drinkability are usually defined as thresholds and the actual water quality gain achieved by different treatment chains shall be considered in the assessment for a fair comparison. Otherwise, chains treating low quality water resources could be disadvantaged as compared to alternatives using higher quality water resource, also when the depletion of the raw resource is included in the impact assessment. In this study, a novel Cost-Performance (CP) indicator has been developed and tested for the case of two existing water treatment plants located in the Paris Region. CP is the ratio between the total environmental impact generated by the treatment (i.e. the LCA score, eventually monetarised) and the total quality gain from raw to treated water. For the test case, three life cycle impact assessment methods, ReCiPe, Stepwise and Eco-costs (the latter two including monetarisation) have been considered. The water quality gain is based on 8 relevant parameters measured before and after treatment. The parameters are further aggregated using the French water quality valuation system SEQ-Eau. Paired t-test is then used to calculate the confidence interval for the average quality gain which then determines the confidence interval of the CP. Independent t-test on the CPs of the two alternative plants allows checking if their performances can be distinguished. Although in the specific test case the comparison is not conclusive, due to the similarity between the water quality gains, realistic breakthrough values have been obtained, especially using ReCiPe. The meaningfulness of the monetarisation of the LCA results has been highlighted as well.

Is it better to remove pharmaceuticals in decentralized or conventional wastewater treatment plants? A life cycle assessment comparison.

After ingestion, pharmaceuticals are excreted unchanged or metabolized. They subsequently arrive in conventional wastewater treatment plants and are then released into the environment, often without undergoing any degradation. Conventional treatment plants can be upgraded with post treatment, alternatively the removal of pharmaceuticals could be achieved directly at point sources. In the European project PILLS, several solutions for decentralized treatment of pharmaceuticals at hospitals were investigated at both pilot plant and full scale, and were then compared to conventional and upgraded centralized treatment plants using Life Cycle Assessment (LCA). Within the scope of the study, pharmaceuticals were found to have a comparatively minor environmental impact. As a consequence, an additional post treatment does not provide significant benefits. In the comparison of post treatment technologies, ozonation and activated carbon performed better than UV. These results suffer however from high uncertainties due to the assessment models of the toxicity of pharmaceuticals in LCA. Our results should therefore be interpreted with caution. LCA is a holistic approach and does not cover effects or issues on a local level, which may be highly relevant. We should therefore apply the precautionary ALARA principle (As Low As Reasonably Achievable) and not conclude that the effect of pharmaceuticals is negligible in the environment.