Study of nitrogen removal performance in pilot-scale multi-stage vermi-biofilter: operating conditions impacts and nitrogen speciation transformation

Abstract

The present work investigates pollutant removal and the transformation of nitrogen from sewage wastewater using a pilot-scale multi-stage bio-vermifilter system. Over a study period of 48 weeks, the pollutant removal performance of the system was measured and the effects of hydraulic loading rate (HLR) and dry-wet ratio (D/W) were estimated. The relationship between oxygen transfer rate and load of oxygen necessity was calculated and analysed for system optimisation. The method for diluting the isotope d 15 N-NO 3 -was applied to study nitrogen transfer. Moreover, statistical correlations were analysed to determine the crucial factors which influence nitrogen transfer efficiency. The system removes pollutants efficiently; specifically, the average removal efficiencies are 94.2 % for chemical oxygen demand (COD), 93.3 % for NH 4 ? -N, and 58.2 % for total nitrogen (T-N). Lowering HLR and D/W can enhance nitrogen removal. Nitrogen speciation and transformation were examined under an optimised condition with an HLR of 0.36 m day -1 and a D/W of 3. The results of isotope d 15 N-NO 3 -dilution showed that NO 3 --N was mainly produced in trickling bio-filter and vermibio-filter (VBF)

A Combined Vermifiltration-Hydroponic System for Swine Wastewater Treatment

“…Removal efficiencies from 95 to 99% were observed, comparable to the efficiency of more sophisticated swine manure treatments such as immobilized cells' reactors [10]. Wastewater treatment by vermifiltration has been reported to favor nitrification processes [20,21,29]; the present results support those observations. Nitrite content showed a general decrease along the hydroponic treatment.…”

“…Nitrate has been shown to increase due to nitrification activity in vermifilters [21,29]. For the hydroponic treatment, nitrate removal as nutrients for plants was hypothesized.…”

“…A drawback of earthworm waste and wastewater treatments is the reported increase of nitrate [22,29] and phosphorus [22,30,31], increasing the risk of eutrophication by the effluents. Thus, further downstream treatment is needed to remove these contaminants.…”

New developments on vermifiltration as a bio-ecological wastewater treatment technology: Mechanism, application, performance, modelling, optimization, and sustainability

“…As mentioned earlier ammonification, nitrification, and denitrification are the processes through which nitrogen is eliminated from wastewater. Further analysis of the transformation of nitrogen speciation by the δ15N–NO 3- isotope dilution method also confirmed the occurrence of nitrification and denitrification processes [ 90 ]. First, the organic nitrogen is converted to ammonium.…”

Vermifiltration: Strategies and techniques to enhance the organic and nutrient removal performance from wastewater

“…In the last few years, numerous researchers across the globe have improvised a few constructive strategies to the conventional VF technology to trigger the organic and nutrient removal performance. The intensive strategies implemented to intensify the sustainability of the VF technology include thermal insulation (Yang et al, 2011; Yang & Zhao, 2008), intermittent feeding (Li, Li, et al, 2014; Singh, Ray, et al, 2021; Wang et al, 2014; Wang, Luo, Zhang, Lian, et al, 2013), step feeding (Dey Chowdhury & Bhunia, 2021; Verma & Ghosh, 2020; Wang, Luo, Zhang, Lian, et al, 2013; Wang, Zheng, et al, 2011), effluent recirculation (Lourenço & Nunes, 2017a, 2017b), incorporation of macrophytes (Dey Chowdhury & Bhunia, 2021; Samal et al, 2018; Suhaib & Bhunia, 2022a, 2022b; Tomar & Suthar, 2011; Wang et al, 2015; Wang, Guo, et al, 2011; Zhao et al, 2014), selection of earthworm species, optimization of earthworm inoculation density, application of mixed earthworm species (Kumar et al, 2015; Kumar et al, 2016; Nie et al, 2015; Sinha et al, 2008; Tomar & Suthar, 2011; Wang, Luo, Zhang, Lian, et al, 2013), selection of vermibed media and optimization of bed depth (Calheiros et al, 2012; Jiang et al, 2016; Kumar et al, 2015; Nie et al, 2015; Seeger et al, 2013; Wang et al, 2010, b; Wang et al, 2014), optimization of carbon to nitrogen (C/N) ratio of the influent (Huang et al, 2014; Li, Xing, et al, 2014; Li, Xing, Yang, & Lu, 2013; Shackle et al, 2000; Zhao et al, 2010; Zhao et al, 2012), provision of pretreatment facilities (Dey Chowdhury & Bhunia, 2021; Li et al, 2013, b; Wang et al, 2016), strategies to improve natural aeration inside the vermibed (Dey Chowdhury & Bhunia, 2021), and incorporation of dolochar layer to facilitate phospho...…”