Centre for Water Resources Research, School of Architecture, Landscape and Civil Engineering, Newstead Building, University College Dublin, Belfield, Dublin 4, Ireland.
Environ Sci Pollut Res Int. 2011 Sep;18(8):1414-21. doi: 10.1007/s11356-011-0507-3. Epub 2011 Apr 13.
BACKGROUND, AIM AND SCOPE: Treatment performance of constructed wetlands (CWs) is largely dependent on the characteristics of the wastewater. Although livestock wastewater is readily biodegradable in general, its variety in biodegradability can still be significant in practice. In addition, it is a common practice to periodically use disinfectants in livestock activities for health concerns. Obviously, the residual of the disinfectants in livestock wastewater may have serious inhibitory effect on the microbial activities during wastewater treatment. Thus, the main objective of this study was to examine the variety of livestock wastewater in biodegradability and its effect on the performance of a pilot scale tidal flow CWs (TFCWs) in organic matter and nitrogen removal. Furthermore, investigation of the potential inhibition of the chosen disinfectants on organic matter biodegradation and nitrification was another aim of this study.
The TFCWs system consisted of four-stage downflow reed beds with a hydraulic loading rate of 0.29 m(3)/m(2)·per day. Long-term stored livestock wastewater and fresh livestock wastewater were used, respectively, as feed to the system in different periods. Meanwhile, batch aeration tests were carried out to investigate the difference in biodegradation of the two types of wastewaters. Inhibitions of two types of disinfectants, namely UNIPRED and HYPROCLOR ED, on microbial activities were investigated in laboratory batch tests, with dosage of from 0.05% to 0.5%.
With fresh livestock wastewater, removal efficiencies of up to 93% and 94% could be achieved with average of 73% and 64% for chemical oxygen demand (COD) and TN, respectively. The performance deteriorated when the system was fed with long-term stored wastewater. In the batch tests, the long-time stored wastewater was characterized as non-biodegradable or at least very slowly biodegradable, while the fresh wastewater was readily biodegradable. UNIPRED showed very strong inhibition on both heterotrophic organisms and nitrifiers. Tested inhibition started from content of 0.05%, which is 1/10 of the recommended usage rate. Inhibitory effect of HYPROCLOR ED on COD degradation started from 0.1% and complete inhibition occurred from content of 0.3%, while significant inhibition on nitrification started from 0.1%.
Livestock wastewater could vary significantly in biodegradability and it may turn to be non-biodegradable after a long-term storage. The variety of the livestock wastewater has a decisive influence on the performance of the CWs system, especially in TN elimination. In addition, the application of disinfectants UNIPRED and HYPROCLOR ED may cause serious inhibition on microbial activities and subsequent system failure.
背景、目的和范围：人工湿地（CWs）的处理性能在很大程度上取决于废水的特性。尽管牲畜废水通常易于生物降解，但实际上其生物降解性仍可能存在很大差异。此外，出于健康考虑，牲畜活动中定期使用消毒剂是一种常见做法。显然，消毒剂在牲畜废水中的残留可能会对废水处理过程中的微生物活性产生严重的抑制作用。因此，本研究的主要目的是研究牲畜废水中有机物和氮去除的生物降解性的变化及其对中试潮汐流 CWs（TFCWs）性能的影响。此外，研究所选消毒剂对有机物生物降解和硝化的潜在抑制作用也是本研究的另一个目的。
TFCWs 系统由四阶段下流式芦苇床组成，水力负荷为 0.29 m(3)/m(2)·天。分别在不同时期长期储存的牲畜废水和新鲜牲畜废水作为系统的进料。同时，进行了批量曝气试验，以研究两种类型废水的生物降解差异。在实验室批式试验中，采用 0.05%至 0.5%的剂量，研究了两种消毒剂 UNIPRED 和 HYPROCLOR ED 对微生物活性的抑制作用。
用新鲜牲畜废水，COD 和 TN 的去除效率最高可达 93%和 94%，平均分别为 73%和 64%。当系统以长期储存的废水为食时，性能会恶化。在批式试验中，长期储存的废水被认为是不可生物降解的，或者至少是非常缓慢生物降解的，而新鲜废水是易生物降解的。UNIPRED 对异养生物和硝化菌均表现出很强的抑制作用。测试抑制作用从 0.05%的含量开始，这是推荐使用量的 1/10。HYPROCLOR ED 对 COD 降解的抑制作用从 0.1%开始，完全抑制从 0.3%的含量开始，而对硝化的显著抑制从 0.1%开始。
牲畜废水的生物降解性可能有很大差异，长期储存后可能会变得不可生物降解。废水的多样性对 CWs 系统的性能有决定性的影响，特别是在 TN 去除方面。此外，消毒剂 UNIPRED 和 HYPROCLOR ED 的应用可能会对微生物活性产生严重抑制，从而导致系统失效。
