The pure-MBBR process was applied to remove ammonia in a full-scale micro-polluted-water treatment plant with a daily treatment capacity of 260 × 104 m3/d Guangdong, China. The relationship between treatment efficiency, physical and chemical properties and microbial diversity in the process of biofilm growth was explored, and the oxygen transfer model of biofilm was established. The results show that the effluent of two-stage pure MBBR process is stable and up to standard after 10 days incubation. The nitrification loads of two-stage biofilm was stable on the 14th day. The biomass and biofilm thickness lagged behind the nitrification load, and reached a relatively stable level on the 28th day the species richness of biofilm basically reached a stable level on the 21th day, and the microbial diversity of primary biofilm was higher. In the primary and secondary stage at different periods, the relative abundance of dominant nitrifying bacteria Nitrospira reaches 8.48–13.60%, 6.48–9.27%, and Nitrosomonas reaches 2.89–5.64%, 0.00–3.48%. The pure-MBBR system mainly adopts perforated aeration. Through the cutting and blocking of bubbles by suspended carriers, the oxygen transfer rate of the system was greatly improved.

  • The MBBR process was integrated into a micro-polluted-water treatment plant of 2.6 million tons daily.

  • The nitrification load, biomass, and biofilm thickness stabilized after 10, 14, and 28 d, respectively.

  • The dominant microorganisms at genus level were Nitrospira, Hyphomicrobium, Pedomicrobium, Nitrosomonas, and Pedobacter.

Graphical Abstract

Graphical Abstract
Graphical Abstract
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