Process research of one‐stage partial nitrification‐anammox (S‐PN/A) technology in toilet water treatment and related kinetic simulation

Abstract BACKGROUND Toilet water is a typical wastewater that is abundant and has a low organic carbon‐to‐nitrogen ratio; therefore, it is necessary to explore an economical and efficient treatment option. Partial nitrification‐anammox (PN/A) technology is characterized by low aeration energy consumption and a high nitrogen removal rate. As a process technology that has emerged in recent years, PN/A technology involves operating conditions that require further study. RESULTS In this work, two one‐stage partial nitrification‐anammox (S‐PN/A) reactors were operated to achieve nitrogen removal from toilet water. The total nitrogen removal rate of the two reactors reached 85%. The hydraulic nitrogen load of the first reactor was only 0.03 kg N m –3 ·d –1 , while the hydraulic nitrogen load of the second reactor reached 0.09 kg N m –3 ·d –1 . Nitrosomonas and Candidatus Kuenenia in the reactor were the main functional bacteria for partial nitrification and anammox. Kinetic simulations were performed using AQUASIM 2.0 software. The results showed that, in the partial nitrification system, the higher the (sludge retention time) SRT , the lower the effluent ammonia nitrogen concentration; the optimal operating condition's sludge retention time (SRT) was 10 days and dissolved oxygen (DO) was 0.2 mg L –1 . The higher the SRT in the anammox system, the lower the concentration of ammonia and nitrite nitrogen in the effluent; in addition, the SRT should be greater than 60 days to ensure that as much nitrogen was removed as possible. CONCLUSION In summary, the research results confirm that it is feasible to use PN/A technology to remove nitrogen from toilet water. © 2021 Society of Chemical Industry (SCI).