Microbial community and performance of a partial nitritation/anammox sequencing batch reactor treating textile wastewater

Elisa Clagnan,Lorenzo Brusetti,Silvia Pioli,Simone Visigalli,Andrea Turolla,Mingsheng Jia,Martina Bargna,Elena Ficara,Giovanni Bergna,Roberto Canziani,Micol Bellucci

doi:10.1016/j.heliyon.2021.e08445

Abstract

Implementation of onsite bioremediation technologies is essential for textile industries due to rising concerns in terms of water resources and quality. Partial nitritation-anaerobic ammonium oxidation (PN/A) processes emerged as a valid, but unexplored, solution. In this study, the performance of a PN/A pilot-scale (9 m3) sequencing batch reactor treating digital textile printing wastewater (10–40 m3 d−1) was monitored by computing nitrogen (N) removal rate and efficiencies. Moreover, the structure of the bacterial community was assessed by next generation sequencing and quantitative polymerase chain reaction (qPCR) analyses of several genes, which are involved in the N cycle. Although anaerobic ammonium oxidation activity was inhibited and denitrification occurred, N removal rate increased from 16 to 61 mg N g VSS−1 d−1 reaching satisfactory removal efficiency (up to 70%). Ammonium (18–70 mg L−1) and nitrite (16–82 mg L−1) were detected in the effluent demonstrating an unbalance between the aerobic and anaerobic ammonia oxidation activity, while constant organic N was attributed to recalcitrant azo dyes. Ratio between nitrification and anammox genes remained stable reflecting a constant ammonia oxidation activity. A prevalence of ammonium oxidizing bacteria and denitrifiers suggested the presence of alternative pathways. PN/A resulted a promising cost-effective alternative for textile wastewater N treatment as shown by the technical-economic assessment. However, operational conditions and design need further tailoring to promote the activity of the anammox bacteria.

Highlights

Textile industries are a major concern for water quality
The findings are in agreement with those reported in lab scale studies applying the Partial nitritation-anaerobic ammonium oxidation (PN/A) processes for the nitrogen removal in textile wastewater (η 1⁄4 up to 79%), in animal feed processing wastewater (η 1⁄4 up to 79%), and in diluted food waste digestate supplemented with nitrite (NLR 1⁄4 98.8 NTOT g mÀ3 dÀ1, N removal rate (NRR) 1⁄4 77.5 NTOT g mÀ3 dÀ1, η 1⁄4 76%) [12, 42, 43], and support the feasibility of the partial nitritation (PN)/A for the treatment of recalcitrant industrial wastewater
The feasibility to treat real N-rich wastewater from textile digital printing through the PN/anammox process in a pilot scale sequencing batch reactor (SBR) was evaluated

Summary

Introduction

Textile industries are a major concern for water quality They consume large quantities of water to process fabric (~200 L per kg of fabric produced [1, 2]) while generating large amount of wastewater (17–20% of total industrial wastewater [2]). Microbial treatment technologies are considered as the “next-generation ecological ditches” as they are considered effective and economical for the simultaneous removal of N, phosphorus (P) and heavy metals from wastewaters such as the textile [6, 7, 8, 9]. Conventional biological N removal process for such N-rich wastewater requires intensive aeration and organic inputs/substrates, with the disadvantage of high consumption of energy, production of large amounts of sludge and massive emission of greenhouse gases. The development of alternative cost-effective bioremediation technologies is essential to promote an environmentally sustainable textile industry

Methods

Results

Conclusion