Purple non-sulfur bacteria technology: a promising and potential approach for wastewater treatment and bioresources recovery.

Shortage of water, energy, and bioresources in the world has led to the exploration of new technologies that achieve resource recovery from wastewater, which has become a new sustainable trend. Photosynthetic non-sulfur bacteria (PNSB), the most ancient photo microorganism, not only treats different wastewater types, but also generates PNSB cells, which are non-toxic bioresources and containing many value-added products. These bioresources can be used as raw materials in the agricultural, food, and medical industries. Therefore, PNSB or PNSB-based wastewater resource recovery technology can be simultaneously used to treat wastewater and produce useful bioresources. Compared with traditional wastewater treatment, this technology can reduce CO2 emissions, promote the N recovery ratio and prevent residual sludge disposal or generation. After being developed for over half a century, PNSB wastewater resource recovery technology is currently extended towards industrial applications. Here, this technology is comprehensively introduced in terms of (1) PNSB characteristics and metabolism; (2) PNSB wastewater treatment and bioresource recovery efficiency; (3) the relative factors influencing the performance of this technology, including light, oxygen, strains, wastewater types, hydraulic retention time, on wastewater treatment, and resource production; (4) PNSB value-added bioresources and their generation from wastewater; (5) the scale-up history of PNSB technology; (6) Finally, the future perspectives and challenges of this technology were also analysed and summarised.