Water-Energy-Food-Climate Nexus in an Integrated Peri-Urban Wastewater Treatment and Reuse System: From Theory to Practice

This paper develops a framework for the identification, assessment and analysis of the water reuse-carbon-energy-food-climatic (WEFC) nexus in an integrated peri-urban wastewater treatment and reuse system. This methodology was applied to the municipal wastewater treatment plant (WWTP) of Peschiera Borromeo (Milan, Italy) and its peri-urban district to define the most possible affirmations and conflicts following the EU regulations 741/2020. Results of this work showed that transferring the WEFC nexus from theory to practice can realize sustainable resource management in the operating environment by providing a reduction in greenhouse gas (GHG) emissions, overall energy savings, reduction in water stress and optimization of agricultural practices. Particularly, it was found that if the plant configuration is upgraded to reach water quality class C for water reuse, instead of wastewater discharge, energy savings are estimated to reach up to 7.1% and carbon emissions are supposed to be reduced up to 2.7%. In addition, enhancing water quality from class C to class A resulted in increments in energy and carbon footprint of 5.7% and 1.7%, respectively. Nevertheless, higher quality crops can be cultivated with reclaimed water in class A, with bigger economic revenues and high recovery of nutrients (e.g., recovery of 154,450 kg N/y for tomato cultivation).

Comparative environmental sustainability study of an improved sewage sludge treatment and sludge reuse system based on emergy analysis in China

As the significant residuals in the sewage treatment system, sludge treatment and reuse play a pivotal impact on the environmental sustainability study in China. In this paper, two sewage sludge treatment systems have been investigated, calculated, and analyzed, including the conventional treatment system (Scenario A) and improved reuse system (Scenario B), respectively. The results demonstrate that (1) Compared to Scenario A, Scenario B is a comprehensive system, which integrates a sewage sludge treatment system and a brick production system for sludge recycling. (2) After considering the brick system (scenario B), on the one hand, the sludge treatment capacity has been enhanced and raised sludge utilization; on the other hand, negative influences have also generated due to the non-renewable resources input and several outputs. (3) In Scenario A and Scenario B, the input resources part reflects the main impact (about 59.6% in the entire emergy value). (4) In this new paper, the UEVs are 2.73E + 11sej/kg and 6.29E + 11sej/kg in Scenario A and Scenario B, respectively. (5) The emergy sustainability indexes (ESI) are 0.012292 and 0.00848, which express the weak comprehensive effects in Scenario A and Scenario B. (6) Scenario B has a more extensive range of change than Scenario A because of the more resource input for the sensitivity analysis. Given the all discussions, there are two effective approaches to be used for perfecting environmental sustainability in the Scenario A system and Scenario B system.

Developing a standard methodology for testing field performance of residential greywater reuse systems: case study of a greywater reuse system installed in 23 homes in Southern Ontario

Using shower wastewater to flush toilets decreases the potable water demand of residential buildings, reducing pressure on existing water supplies. “Off- the-shelf” greywater reuse systems intended for single-family residential dwellings have recently become commercially available, but have variable field performance. A standard field testing methodology was developed and applied to a greywater reuse system installed in 23 homes in Southern Ontario. Performance was quantified by measuring the water balance, water quality, energy consumption, durability, maintenance requirements, installation process, economics and user satisfaction with the system. The tested system was found to save, on average, 40.9 litres per household per day, occasionally meet water quality guidelines and generally have less maintenance and durability issues than previous generations, resulting in satisfied users. However, due to low water rates and high capital costs, there is a need for government subsidization of these systems which will ultimately, reduce pressure placed on centralized water infrastructure.

Developing a standard methodology for testing field performance of residential greywater reuse systems: case study of a greywater reuse system installed in 23 homes in Southern Ontario

Using shower wastewater to flush toilets decreases the potable water demand of residential buildings, reducing pressure on existing water supplies. “Off- the-shelf” greywater reuse systems intended for single-family residential dwellings have recently become commercially available, but have variable field performance. A standard field testing methodology was developed and applied to a greywater reuse system installed in 23 homes in Southern Ontario. Performance was quantified by measuring the water balance, water quality, energy consumption, durability, maintenance requirements, installation process, economics and user satisfaction with the system. The tested system was found to save, on average, 40.9 litres per household per day, occasionally meet water quality guidelines and generally have less maintenance and durability issues than previous generations, resulting in satisfied users. However, due to low water rates and high capital costs, there is a need for government subsidization of these systems which will ultimately, reduce pressure placed on centralized water infrastructure.