Resource recovery from sulphate-rich sewage through an innovative anaerobic-based water resource recovery facility (WRRF)

Abstract

This research work proposes an innovative water resource recovery facility (WRRF) for the recovery of energy, nutrients and reclaimed water from sewage, which represents a promising approach towards enhanced circular economy scenarios. To this aim, anaerobic technology, microalgae cultivation, and membrane technology were combined in a dedicated platform. The proposed platform produces a high-quality solid- and coliform-free effluent that can be directly discharged to receiving water bodies identified as sensitive areas. Specifically, the content of organic matter, nitrogen and phosphorus in the effluent was 45 mg COD·L−1, 14.9 mg N·L−1 and 0.5 mg P·L−1, respectively. Harvested solar energy and carbon dioxide biofixation in the form of microalgae biomass allowed remarkable methane yields (399 STP L CH4·kg−1 CODinf) to be achieved, equivalent to theoretical electricity productions of around 0.52 kWh per m3 of wastewater entering the WRRF. Furthermore, 26.6% of total nitrogen influent load was recovered as ammonium sulphate, while nitrogen and phosphorus were recovered in the biosolids produced (650 ± 77 mg N·L−1 and 121.0 ± 7.2 mg P·L−1).

Continuous 3-year outdoor operation of a flat-panel membrane photobioreactor to treat effluent from an anaerobic membrane bioreactor

“…The nutrient-rich influent to the MPBR plant was from an AnMBR plant that treated real sewage (details of this plant and its operation can be found in Seco et al (2018)).…”

“…The wastewater treatment sector thus needs to intensify research on more sustainable technologies, not only to remove pollutants from wastewater but also to recover resources from them, mainly energy, nutrients and reclaimed water (Nayak et al, 2018;Seco et al, 2018).…”

“…AnMBR systems have previously been assessed on a pilot scale, obtaining a high quality effluent as regards organic matter and suspended solids (Seco et al, 2018).…”

“…Microalgae cultivation has emerged as the ideal option to avoid this problem, as it can recover nutrients from AnMBR effluents (González-Camejo et al, 2019a). It also produces valuable microalgae biomass that can be used to obtain biofuels or fertilisers, amongst other applications (Seco et al, 2018;Xu et al, 2019).…”

“…COD e , COD i , COD, N i , sCOD and NO 2 showed low correlations with microalgae performance(Figure 6b). Since COD i came from an AnMBR plant which degraded most of the organic matter content(Seco et al, 2018) and COD e was the permeate of an ultrafiltration system which removed most of the suspended organic matter, their variability was relatively low, so that COD e and COD i concentrations were not expected to have a significant influence on the model. However, the culture's COD concentration was expected to have a stronger influence on the projection model, since the presence of organic carbon in the wastewater has been reported to be able to modify the microalgae cell metabolism, changing their activity (Moreno-García et al, 2019).…”