Release, denitrification performance, and generated waste utilization of alkali-modified lignocellulosic materials as denitrification carbon sources

Three kinds of lignocellulosic materials i.e. corn straw (CS), corn cob (CC) and giant reed (GR) were selected and modified by alkali, and substrate release capacity and denitrification performance of the modified materials and the reuse feasibility of fluid-wastes generated were extensively investigated. All of the selected materials i.e. 4 %-NaOH modified CS (4-CS), 2 %-NaOH modified CC(2-CC) and 4 %-NaOH modified GR (4-GR) had stable carbon release rates, and 4-CS had the best denitrification performance (1.59 ± 0.04 mg N/(g material·d)) during steady period (5 d–21 d). The fluid-wastes generated during modification process had high bio-availability and could be reused as external carbon source to enhance phosphorus and nitrogen removal of an anaerobic-anoxic-oxic-membrane-bioreactor, and the maximum TN removal (71.97 %) was achieved by 4-CS fluid-waste while the maximum TP removal (67.53 %) was obtained by 2-CC fluid-waste addition, which could increase the utilization rate of the lignocellulosic materials, reduce the operation cost, and avoid secondary pollution risks.