Effective nitrification and removal of particulate organic matter in biofilters with compressible polyurethane foam

IF 4.3 2区农林科学 Q2 AGRICULTURAL ENGINEERING

Aquacultural Engineering Pub Date : 2025-05-11 DOI:10.1016/j.aquaeng.2025.102563

Bence Dániel Kovács, Kim João de Jesus Gregersen, Lars-Flemming Pedersen

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引用次数: 0

Abstract

This study evaluated the treatment efficiency and backwashing capabilities of a novel fixed-bed biofilter utilizing compressible polyurethane foam media. The novelty of the biofilter system lies in its custom-designed backwashing mechanism, in which the foam media is mechanically compressed to remove retained solids. The system was tested at two hydraulic retention times (HRTs), 2.4 min (low HRT) and 16 min (high HRT), within a pilot-scale freshwater recirculating aquaculture system (RAS) stocked with rainbow trout over an 18-week period. Assessment included single-pass removal efficiencies and volume-specific removal rates based on inlet–outlet concentrations, as well as particulate matter retention rates derived from sludge collected during backwashing. Results demonstrated immediate treatment effectiveness, operational simplicity, and practical applicability. High HRT reactors consistently achieved higher single-pass removal efficiencies, with peak reductions of 90 % for total ammonia nitrogen (TAN), 66 % for nitrite-nitrogen (NO₂-N), 64 % (Bactiquant) and 48 % (H₂O₂ degradation assay) for bacterial activity, 44 % for turbidity, and a 10 percentage point improvement in ultraviolet transmittance (UVT) — approximately 1.5–3.5 times higher than values observed in low HRT reactors. Conversely, low HRT reactors outperformed in terms of volume-specific TAN and NO₂-N removal rates (67.9 ± 18.6 g TAN/m³/day; 22.5 ± 12.5 g NO₂-N/m³/day), due to increased substrate loading. Low HRT reactors also retained more particulate organic matter in sludge, with average retention rates of 38.2 ± 1.1 g/week for dry matter and 25.7 ± 1.2 g/week for total chemical oxygen demand (COD), compared to 24.8 ± 0.7 g/week and 7.7 ± 0.7 g/week under high HRT, respectively. Backwashing enhanced nitrification without compromising the system stability, however, a temporary reduction in NO₂-N removal was observed following a four-week operational pause.

Overall, this type of fixed-bed biofilter concept demonstrates strong potential for aquaculture applications, offering rapid effectiveness, operational resilience, and modular flexibility for continuous or intermittent treatment of nitrogenous compounds and particulate matter.

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可压缩聚氨酯泡沫生物滤池中有机物颗粒的有效硝化和去除

本研究评估了一种利用可压缩聚氨酯泡沫介质的新型固定床生物过滤器的处理效率和反冲洗能力。生物过滤系统的新颖之处在于其定制设计的反冲洗机制，在该机制中，泡沫介质被机械压缩以去除残留的固体。在一个中试规模的虹鳟鱼淡水循环养殖系统（RAS）中，对该系统进行了为期18周的水力停留时间（HRT）测试，分别为2.4 min（低HRT）和16 min（高HRT）。评估包括单次去除效率和基于进出口浓度的体积比去除率，以及反冲洗过程中收集的污泥产生的颗粒物保留率。结果显示治疗效果立竿见影，操作简便，实用性强。高HRT反应器始终实现更高的单次去除效率，总氨氮（TAN）峰值降低90 %，亚硝酸盐氮（NO₂- n）峰值降低66 %，细菌活性峰值降低64 % （Bactiquant）和48 % （H2O2降解试验），浊度峰值降低44 %，紫外线透过率（UVT）提高10个百分点，大约是低HRT反应器的1.5-3.5倍。相反，低HRT反应器在体积特异性TAN和NO₂-N去除率方面表现更好(67.9 ± 18.6 g TAN/m³/天；22.5 ± 12.5 g NO₂-N/m³/天)，因为底物负荷增加。低荷尔蒙替代疗法的反应堆也保留更多的颗粒污泥中的有机物,保留利率平均为38.2 ±1.1  干物质和25.7 g /一周 ±1.2  g /一周总化学需氧量(COD),相比24.8 ±0.7  g /周和7.7 ±0.7  g /星期在高荷尔蒙替代疗法的情况下,分别。反冲洗在不影响系统稳定性的情况下增强了硝化作用，然而，在暂停运行四周后，观察到NO₂-N去除率暂时降低。总体而言，这种类型的固定床生物过滤器概念在水产养殖应用中显示出强大的潜力，为连续或间歇处理含氮化合物和颗粒物质提供了快速有效性、操作弹性和模块化灵活性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Aquacultural Engineering 农林科学-农业工程

CiteScore

8.60

自引率

10.00%

发文量

审稿时长

>24 weeks

期刊介绍： Aquacultural Engineering is concerned with the design and development of effective aquacultural systems for marine and freshwater facilities. The journal aims to apply the knowledge gained from basic research which potentially can be translated into commercial operations. Problems of scale-up and application of research data involve many parameters, both physical and biological, making it difficult to anticipate the interaction between the unit processes and the cultured animals. Aquacultural Engineering aims to develop this bioengineering interface for aquaculture and welcomes contributions in the following areas: – Engineering and design of aquaculture facilities – Engineering-based research studies – Construction experience and techniques – In-service experience, commissioning, operation – Materials selection and their uses – Quantification of biological data and constraints