Anaerobic ammonium oxidation (Anammox), a promising biological nitrogen removal process, has been verified as an efficient, sustainable and cost-effective alternative to conventional nitrification and denitrification processes. To date, more than 110 full-scale anammox plants have been installed and are in operation, treating industrial NH4+-rich wastewater worldwide, and anammox-based technologies are flourishing. This review the current state of the art for engineering applications of the anammox process, including various anammox-based technologies, reactor selection and attempts to apply it at different wastewater plants. Process control and implementation for stable performance are discussed as well as some remaining issues concerning engineering application are exposed, including the start-up period, process disturbances, greenhouse gas emissions and especially mainstream anammox applications. Finally, further development of the anammox engineering application is proposed in this review.

•Both of the conditioning and biofouling behaviors were investigated.•SA and HA accelerated the conditioning, yet resulted in slighter biofouling.•Most severe biofouling occurred in the presence of BSA.•Ca2+ played an important role in organic conditioning and subsequent biofouling.•Organic conditioning greatly influenced membrane surface properties.Biofouling of nanofiltration (NF) membranes is a major impediment in wastewater reclamation. However, research on the fouling process, including conditioning and subsequent biofouling in complicated systems, is limited. In this study, the combined effects of organic matter (OM) and calcium on Pseudomonas aeruginosa-induced fouling are systematically investigated and verified through an analysis of permeate flux, foulants, and membrane surface properties (roughness, surface charge, hydrophobicity). Sodium alginate (SA), bovine serum albumin (BSA), and humic acid (HA) are selected as model organics for polysaccharides, proteins, and humic substances in wastewater, respectively. Results show that approximately 8% of permeability is lost during organic-free conditioning in the absence and presence of Ca2+. However, subsequent biofouling is reduced at 5 and 8 mM Ca2+. In the presence of OM, Ca2+ plays an important role in organic conditioning and subsequent biofouling. SA and HA accelerate organic conditioning with the increase in Ca2+ concentration but inhibit subsequent biofouling. By contrast, severe biofouling occurs in the presence of BSA at 2 mM Ca2+, as revealed by both flux decline and the biomass accumulation. Organic conditioning significantly influences membrane surface properties and results in biomass retention on hydrophobic and rough surfaces conditioned with BSA.