2025, Vol. 46
2. 中国环境科学研究院湖泊水污染治理与生态修复技术国家工程实验室, 北京 100012;
3. 东华大学环境科学与工程学院, 上海 201620;
4. 哈尔滨工业大学环境学院, 哈尔滨 150090
2. National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Science, Beijing 100012, China;
3. School of Environmental Science and Engineering, Donghua University, Shanghai 201620, China;
4. School of Environment, Harbin Institute of Technology, Harbin 150090, China
磷(P)是生态系统中的重要元素之一, 也是植物生长必需营养元素[1]. 但当地表水中的P过量时会引起水体富营养化[2], 严重影响水生生物生长和人体健康[3]. P在水中的形态较复杂, 包括无机磷(IP)、有机磷(OP). IP以正磷酸盐为主、生物可利用性最高. OP以膦酸盐和有机磷酸酯等为主[4]. 目前污/废水和低污染水处理中除P方法多, 包括吸附、化学沉淀、强化生物除P和人工湿地法[5]. 相对而言, 人工湿地绿色环保、操作简单且较经济.
人工湿地由植物、微生物和基质组成, 利用物理、化学及生物等过程去除水中的磷. 因其能耗低、易操作与生态环境友好等优势, 是可持续、低成本和较少碳足迹的水处理系统[6 ~ 8]. 世界上首座用于处理污水的人工湿地于1903~1992年间在约克郡厄尔比建造并使用, 为后续研究提供了模板[9]. 填料为构建人工湿地的主体, 是处理系统的核心[10], 主要通过吸附除P；微生物通过反硝化、好氧及厌氧吸P等作用驱动人工湿地内部磷转化和去除[11]；植物能将污染物作为营养源用于自身生长, 植物根系还会显著影响人工湿地的功能微生物丰度和代谢多样性[12], 人工湿地各部分在污染物去除中均发挥作用. 人工湿地已被广泛用于净化污水处理厂出水、污染河水和农业径流等低污染水[13], 增加预处理单元的人工湿地用于处理生活污水[14]、垃圾渗滤液[15]和多类型工业废水[16]等, 但是人工湿地在不同地区受进水条件、气候变化及运维影响, 易堵塞且恶臭等, 阻碍了人工湿地长效稳定运行[17].
人工湿地除P机制主要有3种：被基质和植物根部吸附、形成不溶性磷酸盐沉淀及被植物和微生物吸收用于生物质合成[18]. 植物根部可利用晶体表面范德华力吸附可溶性磷. 除植物根部吸附外, 基质在除P吸附和沉淀中也占很大比例. 一方面, 带负电荷磷酸盐可与某些基质表面发生阴离子交换而被吸附[19]. 另一方面, 基质中Ca2+、Al3+和Fe3+等金属阳离子与可溶性P化物发生反应, 形成不溶性磷酸盐沉淀. 植物对P的吸收和储存取决于植物的营养类型和生长特性[20], 当植物生长快, 微生物生物量大, 填料吸附适合条件下有一定除P效果. 但植物和微生物的P吸附能力和除P性能会随季节变化而波动[21], 如冬季植物生长缓慢或植物枯萎时导致人工湿地除P性能降低[22]. 低温也会直接影响微生物酶活性, 微生物活性也随之降低[23], 最终导致人工湿地除P效果不佳. 因此, 厘清人工湿地除P限制因素有助于提出针对性措施.
人工湿地技术组合或过程强化等措施能有效提高其除P能力. 早期人工湿地常经表面流人工湿地和水平潜流人工湿地来除P[24]. Ge等[25]以天然黄铁矿和石灰石为基质构建人工湿地, 经3 a研究发现TP去除率比常规人工湿地提高了53%. Hou等[26]构建了以海绵铁为阴极填料的微电解辅助人工湿地以强化除P, 对照实验表明相对于原工艺TP去除率提高了约70%. 可见, 通过对人工湿地基质或填料强化技术创新带来除P率显著提高. 近10年来, 人工湿地还与生物电化学系统结合, 包括人工湿地-微生物燃料电池、电化学湿地、电活性湿地和基于微生物电化学技术等人工湿地技术[27]. Wang等[28]开发了电化学耦合垂直流人工湿地小型装置, 在三级污水处理中PO43--P去除率可达89.7%~99.4%, 比耦合前的椰子纤维填料提高了58%. 但尚未对近年来快速发展的人工湿地强化除P技术总结归纳, 本研究旨在通过对人工湿地除P机制与影响因素分类, 梳理近年来人工湿地除P强化措施, 供人工湿地强化除P研究与应用参考.
1 人工湿地除磷机制 1.1 吸附除磷人工湿地吸附除磷主要是利用比表面积较大或多孔的基质吸附水中IP或OP[29]. 目前, 高岭石、蒙脱石和锂皂石等黏土矿物表面的可变电荷位点可吸附回收水中P[图 1(a)][30]. 不同P种类吸附原理不同, 通常, P在填料表面的吸附是由内外层表面络合、表面扩散和氢键相互作用得以去除. Zhou等[31]构建了以铁改性铝污泥为基质的潮汐流人工湿地, 铁屑进入铝污泥的分子层, 形成了利于吸附污染物的层间结构, 因而铁改性铝污泥层中的P主要以Fe/Al-P形式存在[图 1(b)]. 此外, 石英砂层和铁改性铝污泥层中的可溶性磷含量最少, 可能由于植物和微生物更易利用晶体表面范德华力吸附可溶性磷. Shang等[32]研究了新型的镧氨改性热液生物炭作为人工湿地改性基质, 其在pH值、离子强度等条件下均具较高吸附容量(以P计, 43.1 mg·g-1), Langmuir等温线模型表明P吸附活性位点均匀分布在镧氨改性热液生物炭表面, 支持其单层吸附. 此外, 对于P在湿地内不同吸附位置的去除也有显著区别, 除填料吸附外还会有少部分P被微生物和植物根吸附.
|
(a)锂皂石吸附磷酸盐机制[30], (b)Fe驱动的N-P协同去除机制[31], (c)水葫芦、水莴苣和狐尾藻的除磷机制[36] 图 1 吸附除磷机制 Fig. 1 Mechanism of phosphorus removal by adsorption |
近年来, 人工湿地物理吸附和化学吸附除P研究很多. Gao等[33]研究了在人工湿地中采用电解结合生物炭技术强化水中P去除, 表明植物和微生物可通过牺牲铁阳极原位形成Fe3+引起P物理吸附, 提高P去除率. Xu等[34]研究了含钛高炉渣人工湿地除P性能, 结果表明含钛高炉渣和转炉炼钢渣除P主要依靠化学吸附, 而石材填料主要依靠物理吸附. 植物在人工湿地除P中起重要作用, 其通过气压梯度和扩散将光合作用和大气中获得的氧气输送到根系, 植物的茎、叶和根为微生物提供附着位点[35], 从而提高除P率. Lu等[36]研究了水葫芦、水莴苣和狐尾藻对主要污染物的去除机制, 表明实验运行20 d后可溶性活性磷和TP浓度分别下降了54%和36%, 且水葫芦、水莴苣和狐尾藻通过微生物在污泥形成后吸附在植物根部去除TP的比例分别为40%、34%和15%, 说明前两者的根系为微生物生长提供了适宜环境, 利于除P[图 1(c)]. 但是, 在人工湿地长期运行下经过填料对P的不断吸附, 其净化力逐渐降低, 最终吸附容量达到饱和, 造成系统堵塞, 使除P效果下降. 如张明珍等[37]研究得出人工湿地系统151 d堵塞后TP去除率从60%降至20%. 对此可以采用一些措施, 包括湿地组合处理、选择大粒径填料、建立反冲洗设施以及更换部分已污染填料等[38]. Hu等[39]通过湿地组合, 在潜流湿地前增加表面流湿地, 延长了水力停留时间, 降低了后续单元负荷, 减少堵塞. 谢志刚等[40]研究了间歇性水和空气联合反冲洗处理后对反应器影响, 结果表明渗透率可恢复到60.0%以上.
1.2 吸收除磷人工湿地通过植物吸收除P不仅可直接吸收利用环境中的少部分P[41], 还可吸收经微生物转化释放的有效P, 最后经植物收割将P带离湿地. 不同种类植物吸收能力有别, 植物的P吸收能力差异主要是由于污水中P浓度及植物在不同生长阶段的呼吸、光合、同化效率等差异造成, 且植物生物量可显著提高其吸收能力[42]. 李龙山等[43]研究了5种湿地植物(芦苇、水葱、千屈菜、扁秆藨草和长苞香蒲)对生活污水的除P效果, 结果表明生长健壮的植物能够吸收污水中89.7%~97.9%的P元素, 且扁秆藨草的TP累积能力高于水葱和千屈菜, 但对污水中TP去除率却较低, 这可能是扁秆藨草的生物量小于水葱和千屈菜导致的. 卫小松等[44]研究发现4种湿地植物(菖蒲、茭白、水葱和美人蕉)的体内生物量和其在地上部对TP的吸收量均按序依次降低. Ruan等[45]研究发现芦竹、风车草和海滨木槿具较高P积累能力, 植物吸收占TP的2%~70%, 且在所有TP去除中芦竹贡献最大, 积累了25%的P. Maucieri等[20]研究比较了潜流人工湿地系统中5种水生植物(薹草、灯心草、虉草、芦苇和香蒲)的除P能力, 表明植物吸收平均提高了PO43--P去除率7.8%, 且香蒲和虉草的较高, 分别为98%和86.2%.
植物生长周期或植物死亡会造成磷的吸收与释放, 因此, 植物种植与管理策略在一定程度上也会影响人工湿地对P去除的效果[46]. 对植物进行收割可以有效防止其长时间滞留在湿地中腐烂再释放所造成的二次污染, 通过收割植物移除水体的P量取决于植物收割的频率、进水负荷、气候条件和植物物种等因素[47], 但多次收割也可能会降低植物对TP的吸收. 因此, 在一些湿地里有必要对某些特定物种的植物进行有规律的收割. 赵梦云等[48]研究了每年11月初对芦苇进行收割后的P吸收能力, 结果表明达到了该年未收割的2倍左右. 此外, 叶磊等[49]研究表明对绿狐尾藻收割后可以将其加工成饲料进行利用, 在实现磷资源化的同时还将产生一定经济效益.
1.3 沉淀除磷P在水中形态复杂, 可通过化学沉淀方式去除人工湿地中的磷酸盐. 通常在人工湿地中添加二价或三价金属盐(如铁或铝), 将水中P离子转化为固体(不溶性盐沉淀物、活性污泥中的微生物质量或人工湿地中的植物生物量), 从而去除高浓度磷酸盐[42]. 由于这些不溶性的磷盐沉淀物在土壤中的微生物分解下会转化成一些溶解性的磷酸盐, 因此, 应重点选取钙、铁、铝等元素含量高并且在合理搭配后可得到适宜pH环境的填料. 在过去几十年中, 学者研究沸石、铝土矿、白云石、腹足类贝壳和脱水明矾污泥等多种填料的固P能力[50]. 通常, 钙镁离子被用作沉淀剂与磷酸盐反应生成磷灰石和鸟粪石[4]. 与正磷酸盐比, 次磷酸盐和亚磷酸盐沉淀物常具较高溶度积常数, 限制了化学沉淀去除. 因此, 可通过高级氧化技术先将次磷酸盐和亚磷酸盐氧化为正磷酸盐, 再沉淀[51][图 2(a)].
|
(a)从含次亚磷酸的废水中以FePO4的形式回收磷[51], (b)不同氧化铁量的人工湿地的除磷性能[56] 图 2 沉淀除磷机制 Fig. 2 Mechanism of phosphorus removal by precipitation |
Shen等[52]研究了以铁屑和生物炭为原料的微电解强化人工湿地对除P性能的影响. 表明由于基质(20%)-铁屑(60%)组合系统(除P率88.10%± 5.00%)和基质(20%)-铁屑(80%)组合系统(除P率93.63%±5.30%)的pH高达8, 溶解的Fe2+和Fe3+会转化为亚铁和氢氧化铁, 可更好去除. Strang等[53]研究了池塘和岩石对除P的重要性, 溶解度分析表明除磷效果好的原因可能是钙硬度水平为中等(60 g·m-3). Zeng等[54]研究了添加镁催化剂后对磷回收率的影响, 发现加入MgO后, OP回收率从5.25%提高到93.42%, 且当pH=10时, 磷回收率达98.47%. 其中回收产物以氧化镁和鸟粪石为主, 均可作为肥料使用. Leng等[55]研究发现镁、铝和钙离子都存在于石榴石中, 以石榴石为基质的人工湿地耦合微生物燃料电池系统对磷的去除主要是石榴石组分从基质表面扩散到水溶液, 与污水中游离磷酸盐和磷酸氢根离子发生反应, 形成附在基质表面的Mg4(PO4)2OH、AlPO4(H2O)1.5和CaPO4沉淀物, TP去除率达92.4%. Hu等[56]研究发现添加适量褐铁矿利于人工湿地去除PO43-[图 2(b)], 表明PO43-和Fe3+的互作形成了FePO4, 因其在水中低溶解度会立即沉淀在填料表面, TP去除率可达77.73%. 此外, 钙含量与累积磷间存在很强相关性, 如双壳类贝壳含大量CaO(51%~54.7%), 固磷能力较强. Nguyen等[57]通过添加白硬蛤壳填料以改善人工湿地除P性能, 发现白硬蛤壳可加强富磷废水中P去除, 平均除P量为(0.32 ± 0.03)g·m-2·d-1.
2 人工湿地除磷影响因素 2.1 填料吸附能力不同填料的最大磷吸附容量差异较大, 显著影响人工湿地除磷能力. 目前填料种类繁多, 按来源可分3类：①砾石、沸石、麦饭石和石灰石等天然材料, 无需加工或稍作预处理即可直接为湿地所用；②工农业副产品如钢渣、粉煤灰、石英砂和牡蛎壳等, 常指工农业生产过程中的残留物；③生物炭、活性炭和生物陶瓷等合成填料, 指在实验室合成的材料或由天然材料经各处理工艺制备得到的具有改变性质的新材料[19]. 在不同人工湿地中选择合适填料是提高除磷能力的关键, 表 1总结了不同种类填料的除P性能.
|
表 1 多种填料性质与P去除率总结 Table 1 Summary of properties and P removal rates of various fillers |
Wang等[58]研究了以粉煤灰为原料, 用酸氧化改性和Fe离子负载法制备的新型中性填料(FA-SFe), 通过间歇实验得到填料吸附等温线, 表明FA-SFe对TP的吸附平衡时间较短(< 30 min), 且该填料对TP的理论最大吸附量(0.47 mg·g-1)高于普通天然或人造材料. Li等[59]对比研究了红砖、沥青混凝土和砾石的P吸附能力, 表明红砖的孔隙结构(< 5 μm)比沥青混凝土和砾石发达, 红砖和沥青混凝土的阳离子交换能力略高于砾石, 可提高金属离子与PO43-反应沉淀, 从而提高除P率. Wang等[60]采用非燃烧工艺制备了能有效固磷的人工湿地填料, 通过对磷的吸附机制研究表明填料内部和表面存在大量微孔和吸附结合位点, 且适度碱性环境利于吸附容量增加, 吸附完成后模拟含磷废水除P率可达95%. Li等[61]制备了新型不燃烧聚合氯化铝渣复合填料, 表明对磷酸盐吸附主要机制是配体交换和路易斯酸碱互作, 复合填料除P率高达90%, 磷酸盐最大吸附量达42.55 mg·g-1.
2.2 氧环境氧环境与微生物活性密切相关, 聚磷菌在有氧条件下吸P, 在厌氧条件下释P. 在厌氧条件下, 磷化合物能提供短链挥发性脂肪酸, 可以被聚磷菌直接利用. 虽然在遇到涨潮情况时也会将菌体内的聚磷释放, 但总的来说, 聚磷菌在富氧条件下吸收转化的磷的量大于其在厌氧环境中释放的量, 故聚磷菌在除P方面有一定作用. 变形菌门被认为是除磷系统中占主导地位的聚磷微生物, 其在好氧阶段吸P能力取决于厌氧P释放过程中合成的聚羟基链烷酸酯的量, 合成量越大, P吸收能力就越强. Ramdat等[75]比较了潮汐流人工湿地和水平潜流人工湿地的有机物和养分去除率, 表明在稳定阶段潮汐流人工湿地TP去除率高于水平潜流人工湿地, 归因于潮汐运行在有氧条件下增强了聚磷菌的磷吸收, 微生物生物量从(2.13±0.14)mg·g-1(水平潜流)增至(4.64±0.18)mg·g-1(潮汐流). 溶解氧升高还可促进金属氢氧化物生成并与磷快速形成沉淀. Li等[76]研究了不同基质潜流人工湿地在前段间歇曝气脱磷效果, 表明曝气模式开始后, 以陶粒+硫铁矿为基质的人工湿地TP去除率剧升, 因曝气利于基质释放的Fe2+转化至Fe3+, 在水中会迅速水解形成一系列羟基络合物吸附在磷水溶液中, 形成了铁磷络合物.
2.3 植物生长情况在人工湿地中磷浓度对植物生长至关重要, 偏低或高都会影响水生植物生长[77]. 通常, 植物可利用其根部从水中吸收大多数形式磷, 根系越发达, 植物处理水的能力越强. 但不同种类植物因其根长度、质量、活性等差异除P效果有别, 表 2总结了植物类型及种类与不同P的类型、进水浓度及去除率的区别.
|
|
表 2 植物类型、种类与P去除率的总结 Table 2 Summary of plant types, species, and P removal rate |
植物根系在湿地净化中起重要作用, 通过根系分泌物调节细菌多样性和相对丰度, 还通过氧气运输影响污染物去除, 其代谢产物还可增强酶合成与活性. Zhang等[78]探究了湿地植物生理调控机制和在“根系垂直空间应力”下的去除潜力, 表明美人蕉增加了根茎生物量分配、根系分泌物的浓度和根冠比, 使TP去除率保持在87%以上. Li等[79]研究了影响8种水生植物净化能力的关键因素及污染物去除机制, 结果表明水竹芋、水芹和黄菖蒲根系发育较好, 具较好净化性能, TP去除率最高达85.87%, 其碱性磷酸酶活性也最高.
此外, 植物地上部、块茎和根部TP含量处理初期末期有别. 植物地上部是各种光合作用反应中心, 通常可保留更多P, 但它们的养分吸收与积累可能根据其不同种类形态而有别. Liu等[80]研究了2种不同阳极的电解辅助水平潜流人工湿地在寒冷季节的净化性能, 表明鸢尾地上部中P积累量高于块茎和根部, 且在湿地中观察到鸢尾根系重量减少, 根系长度缩短及根系TP量降低等现象. Luca等[81]研究了在漂浮处理湿地中种植香蒲对污染物去除的影响, 表明TP去除率可达95%, 植物叶片和根系最终P含量均显著高于其初始值, 且具根部粗短, 根毛丰富等良好生长状态, 但P在根和根茎中的浓度显著高于地上部分, 与上述例子形成反差.
2.4 气温气温在人工湿地除P过程中起重要作用, 温度变化对微生物活性、底物利用率和吸附速率有影响. 因我国属大陆性季风气候, 据监测, 在寒冷气候下污水温度可低至8~15℃, 甚至低于5℃, 低温会显著降低一些类型人工湿地(如水平潜流人工湿地)中污染物去除能力. 在潮汐流人工湿地中采用的创新增氧操作, 被证明是提高人工湿地低温影响下的有效技术. Wang等[101]比较了潮汐流和水平潜流人工湿地在一定温度范围内的有机物和养分去除率, 表明随温度在20~40℃增加时磷酸盐积累生物(假单胞菌)增加, 潮汐流TP去除率(57.38%)高于水平潜流(46.75%).
温度也是影响水生植物生长的重要因素之一, 不同植物适宜生长的最佳温度也有差异, 常为20~32℃[102]. 通常, 在温暖季节植物处于生长发育期时具有较好吸P能力, 在寒冷季节大部分植物进入休眠或枯萎期, 从而影响人工湿地除P率. Li等[103]研究了8种水生植物(2种浮水和6种挺水)在夏季对进水中高浓度P去除效果, 表明水鳖、黄花水龙、千屈菜和慈姑在夏季(昼夜温度分别为33~35℃和25~27℃)都有较高的除P率(超过95%), 高浓度P虽抑制了千屈菜高度和根长, 但增加了其茎粗和叶长. Carrillo等[104]比较了普通植物与观赏植物在人工湿地中单作和混种中的P吸收情况, 表明单一栽培在较低温度(8.9℃)下会降低吸收, 混种系统的效果更好, 例如纸莎草和马蹄莲混种对P吸收量在暖季(最低气温18℃)为17%, 在冷季(最高气温12℃)为27%.
2.5 其他影响因素除上述因素外, 植物种类, 填料组成, 植物种植方式, 污水盐度水平和C/N等因素也会对除P率有影响. Chen等[105]利用废砖和砾石人工湿地研究了生活污水中除P率及迁移特性, 表明两种体系中P积累主要集中在地面, 植物吸收作用较小, 不同植物部位全磷含量依次为：叶 > 茎 > 根, 废砖和砾石湿地对除P贡献率分别为9.64%和12.5%. Luo等[106]研究了人工湿地不同生长型的植物单作和混种时植物生长和养分吸收差异, 表明混种显著提高了TP去除率, 且大型植物在混种中生物量比细长和扇形植物增加的生物量更大, 吸收TP加速. Liang等[107]研究发现盐的共存会影响植物对P的吸收和根际微生物活性, 地上部和根部TP含量随盐度水平增加而增加, 但高盐度(EC=30 mS·cm-1)会降低植物吸收P. 以上可见, 不仅植物种类对P吸收效果有影响, 填料组成、植物种植方式、污水盐度水平等也都有影响.
此外, 有研究表明TP去除率会在一定限度下随C/N的增加而提高. Jiang等[108]研究了黄铁矿和碱改性稻壳作为人工湿地脱氮除磷基质时, 在不同碳氮比下对系统性能的影响, 结果表明当C/N分别为1.5和3时, 组合基质的人工湿地TP去除率分别为89.18%±6.35%和96.19%±2.85%.
3 人工湿地除磷强化措施 3.1 填料强化除磷使用除磷效果较好的填料代替人工湿地中的部分或全部填料是提高人工湿地强化除磷的重要措施之一. 传统的填料如砾石、土壤和沙子等在人工湿地除P率较低, 近年来, 钢渣、陶粒、沸石和海绵铁等新型多孔填料在人工湿地除磷技术中得到了广泛应用[10]. 对于垂直流人工湿地填料强化除磷, 可以分为全部填料替换或分层替换等形式, 水平潜流人工湿地则通过分段替换填料来强化除磷.
在填料的不断发展中出现了一些以废物利用为填料的实例, 事实证明以此为填料除P效果也是可观的. Li等[109]研究了非燃烧聚合氯化铝渣复合填料与常规填料(砾石和陶粒)在低温(0~15 ℃)下的除P率, 结果表明复合填料的除P率(99%)优于砾石(18%)和陶粒(21%). Li等[59]以红砖、混合建筑垃圾再生骨料(红砖和沥青混凝土质量比为1∶1)和砾石为填料进行研究, 结果表明对TP的平均去除率从高到低依次是红砖(46.98%)、砾石(39.12%)、混合建筑垃圾再生骨料(27.81%). Wang等[110]比较了由陶粒沸石的混合与砾石两种填料组成的人工湿地对磷的去除能力, 结果表明以混合填料(陶粒和沸石)为床层的除P率优于(改善5%)砂砾石作为床层的除P率, 且混合填料(陶粒和沸石)更适合植物的生长. 据统计, 我国聚合氯化铝生产企业每年至少生产60 kt聚合氯化铝渣[109]；同时, 我国持续城市化导致建筑和拆除废物的排放量逐年增加, 然而回收率仅为5%, 这都导致大量废物废渣被随意倾倒或填埋在现场, 对空气、水和土壤构成潜在的污染风险. 若将对这些废物废渣进行回收再利用作为人工湿地的填料, 将对强化除P率有很大的提高.
应用于人工湿地处理废水的填料的研究不仅集中在载体等化学组分上, 还集中在一些改性活性填料的研究热点上, 例如, 木质素和牡蛎壳等作为活性填料被用于处理城市污水. 其中, 牡蛎壳具有16 g·kg-1的磷吸附能力. Tao等[111]研究了添加纤维素填料(由纤维素、半纤维素和木质素组成)的水平流人工湿地对典型污染物的去除能力, 结果表明用添加纤维素填料前后的人工湿地对TP的去除率从78.90%提高到了88.21%. Wang等[112]研究了牡蛎壳、碎砖、火山岩和沸石作为猪废水处理基质时的理化性质和磷吸附能力, 结果表明牡蛎壳的磷吸附量最高(32.9 mg·g-1), 其次是碎砖(0.594 mg·g-1)、火山岩(0.227 mg·g-1)和沸石(0.043 mg·g-1).
3.2 微生物强化除磷人工湿地中通过微生物接种提高除磷能力是一种有效的处理技术. 微生物在除磷中起着重要作用, 其在厌氧条件下会吸收过量的磷, 并影响着P元素的形态. 例如, 根际细菌如光合细菌会促进植物生长[113], 它们分泌有机酸(例如草酸和柠檬酸)可以将土壤中的不溶性磷转化为根际中可以被植物吸收的可溶性磷, 还有一些细菌分泌物(例如有机酸)会影响磷的溶解度. 有研究报告发现, 潮间带湿地沉积物是一种潜在的微生物接种剂, 可用于人工湿地系统接种以处理废水中的磷. Wang等[114]研究了以潮间带湿地沉积物作为处理盐废水的新微生物来源的人工湿地除磷性能, 结果表明有潮间带湿地沉积物的人工湿地的磷去除率(89.03%±1.47%)高于对照组(82.35%±1.58%), 且前者中存在较多与除磷相关的活性细菌, 如磷积累生物、磷溶解细菌, 这些细菌通过微生物转化增强了磷的去除. Tan等[115]在潮汐流人工湿地中添加了异养硝化-好氧反硝化细菌增强P的去除, 结果表明在梯度氧环境中对TP的平均去除率可达到92.4%.
此外, 微生物受环境温度变化影响较大, 可通过添加具有特定功能的耐低温微生物来改善人工湿地中TP的去除. Gao等[93]研究了在低温期(0~10℃)添加耐低温的微生物菌剂(芽孢杆菌)对垂直地下流人工湿地中污染物的去除影响, 结果表明添加耐低温微生物后湿地中TP的去除效率略有提高(8.68%), 但是在植物(水芹)和微生物的联合增强下对TP的去除率提高量最大(14.57%). 另外, 在门水平上, 铁氧化微生物主要包括硝基螺旋门、厚壁菌门和变形菌门, 其可在有氧或缺氧/厌氧条件下将Fe2+氧化至Fe3+, 从而合成有机物. Tian等[116]研究了添加不同浓度的外源性Fe2+对人工湿地中TP的去除, 结果表明增加Fe2+会降低微生物丰度并提高耐受物种丰度, 在含Fe2+的人工湿地中TP去除率提高了0.63%~31.62%.
3.3 植物强化除磷根据南北温度差异、植物根部生长发育等不同特征条件, 使用植物强化改造人工湿地内外部的过程可以提高除P率. 例如, 使用一些水生大型植物可有效改善水质并降低废水中磷的浓度. 美人蕉、芦苇、香蒲和紫松等植物因其高去除效率和美学价值被广泛用于人工湿地改善水环境质量, 并且某些植物的通气组织可得到最高去除率. 虽在寒冷气候中, 温度会影响人工湿地中芦苇组织的磷释放从而降低除P率[117]. 因此为确保有效去除污染物, 植被物种选择格外重要. 另外, 沉水植物也可通过其根部在浅富营养化水体中吸收沉积物中大量磷. Pavlidis等[118]研究了秋冬季节种植浮萍和水葫芦的人工漂浮湿地的去除污染物能力及受气候参数的影响, 结果表明两种植物的PO43--P去除率与无植物相比明显较高, 并且高温下PO43--P的去除率更高.
此外, 与单一物种的湿地相比, 如果考虑人工湿地中植物物种间的相互作用, 比如在极端条件下某些植物之间会存在功能互补性、某些植物的种间竞争, 则一些水生植物的混种可利于除P. Zhu等[119]研究了植被类型和环境温度对人工湿地性能的影响, 结果表明美人蕉和千屈菜的混种对TP的去除率(92.6%)大于单作的去除率, 且即使温度降至约8.9℃混种组的TP去除良好. Luo等[106]以单作、组合(2种相同生长型)和混种(6种3个生长型)为研究对象, 比较了不同处理的植物生长和养分吸收差异, 结果表明混种显著提高了TP去除率, 且美人蕉和水竹芋在混种中生物量增加较大, 加速了TP的吸收和同化. Zheng等[120]研究了6 a间以芦苇和香蒲混种的人工湿地对TP和PO43--P的去除率, 结果表明种间竞争提高了植物对TP和PO43--P的去除率, 并且呈逐年递增状态.
3.4 与其他除磷技术组合强化除磷进水碳源缺乏和基质吸附有限是导致传统人工湿地无法达到较好除磷效果的重要原因. 近年来, 有学者研究表明使用人工湿地与其他技术耦合可提高除P率. 通常, 人工湿地可与生物处理的混合系统、曝气生物膜反应器、电化学系统、光催化和Fenton等技术组合, 大大提高污染物去除效果.
Zhang等[121]研究了位于广州(中国东冲)附近农村地区的一个罗非鱼生产小规模水产养殖场中, 以氧化铁涂层砂为填料的新型曝气生物膜反应器与人工湿地系统结合技术对污染物的去除影响[图 3(a)], 结果表明在监测70 d内糖酵解途径中显示出高丰度的关键酶基因, 促使生成FePO4, 有效提高了TP去除率(90%~94%). Gao等[33]研究了在人工湿地中采用电解结合生物炭技术强化废水中磷去除, 结果表明铁板作为阳极电离出的铁离子与PO43--P形成了沉淀, 使其去除率从65.98%提高至96.73%. Chen等[122]研究了光催化技术[图 3(b)]改变了磷聚集细菌群落结构使其丰度增加, 与人工湿地耦合后使TP去除率从68.54%提高至80.36%.
|
(a)曝气生物膜反应器与人工湿地[121], (b)光催化人工湿地[122], (c)藻池与人工湿地[123], (d)厌氧消化-微藻电活性生物膜人工湿地[124], (e)人工湿地铁碳微电解[127] 图 3 人工湿地与其他除磷技术组合应用 Fig. 3 Coupled application of constructed wetland with other phosphorus removal technologies |
藻类因其独特优势可充分利用污水中磷, 如蓝藻能通过纳米线转移电子, 微藻具过量吸储磷能力, 为人工湿地污水处理和资源化耦合技术探索开辟了道路. Yang等[123]研究了藻池与人工湿地耦合能力[图 3(c)], 微藻具有过量吸收P和储存的能力, 结果表明在最优条件下TP去除率较单一人工湿地提高了416.4%, 且可回收83.9%的TP作为生物资源. Wang等[124]研究了厌氧消化-微藻电活性生物膜人工湿地, 由于微藻通过CO2光合作用, 导致废水中的pH值升高, 使磷酸盐从废水中沉淀[图 3(d)], 结果表明夏季和冬季总磷的总体去除率分别达到91.44%和91.52%.
人工湿地与生物电化学系统相结合成为新型高效低强度废水处理技术. 微生物燃料电池通过填充具有导电性质的碳质材料, 可将废水中的化学能转化为电能, 且减少产泥量、回收能量. 铁碳微电解在不同深度下具较强内部氧化还原环境和优异吸附能力[125], 若能与人工湿地结合皆可发挥最大优势有效除P. Wang等[126]研究了通过在人工湿地-微生物燃料电池系统中使用耐盐电活性菌-藻类生物膜对污染物去除率的影响, 表明K2HPO4通过细胞膜内的转运蛋白直接进入微藻细胞, 促进除P, 该系统对TP去除率闭路(90.81%±5.67%)高于开路(61.98%±3.51%). Zheng等[127]研究了人工湿地与铁碳微电解体系相结合技术对污水处理厂含盐出水中磷的去除率[图 3(e)], 结果表明人工湿地-铁碳微电解体系的TP去除率(83.21%)高于常规人工湿地(24.81%).
4 展望人工湿地是一种绿色环保、经济高效的污水处理技术, 因其具有成本低、可持续、易于管理等优点多被用于污水处理. 未来对于人工湿地除磷机制、影响因素及强化措施等方面的研究可以从以下4个方面开展：
(1) 人工湿地除磷机制的研究. 随着新型填料的发展, 填料在人工湿地中的除磷作用成为湿地除磷机制研究的重点, 除常规的吸附、沉淀外, 填料与植物、微生物相互作用除磷机制均值得进一步研究.
(2) 人工湿地除磷影响因素的深入研究, 未来应该更加关注填料配比、孔隙度、氧环境、C/N等因素, 同时也应当综合考虑不同的湿地构型, 关注不同种类的植物对除磷的效果.
(3) 人工湿地强化除磷方式的研究. 寻找更加高效、吸附量高的填料, 优化吸P效果好的植物, 开展在某些耐受情况下(高盐、低温)低成本研究是未来发展的重点.
(4) 人工湿地除磷耦合技术. 针对于含磷与多种污染物, 综合考虑优势互补的物化技术, 无论是将此技术作为前处理或者是与其他共同处理污水的耦合装置, 都是未来研究的重点.
5 结论人工湿地作为一种绿色、低耗高效技术用于除磷能力较强. 在人工湿地中, 主要通过填料、植物及微生物的吸附、吸收及沉淀等机制去除磷. 填料吸附能力、氧环境及植物生长情况对湿地系统除磷有显著影响, 其在多种因素影响下调控湿地运行参数使其保持最优去除性能仍是未来研究方向. 人工湿地系统中通过填料、植物及微生物强化与其他技术耦合可显著提升除磷能力, 但技术耦合等措施仍存在工程应用效率低、有二次污染等难题亟需攻克.
| [1] | Vijuksungsith P, Satapanajaru T, Chokejaroenrat C, et al. Removal and reuse of phosphorus from aquaculture water using activated carbon-based CaO2 nanoparticles[J]. Environmental Technology & Innovation, 2023, 29. DOI:10.1016/j.eti.2022.102990 |
| [2] | Shen C, Zhao Y Q, Li Y, et al. Treating carbon-limited wastewater by DWTR and woodchip augmented floating constructed wetlands[J]. Chemosphere, 2021, 285. DOI:10.1016/j.chemosphere.2021.131331 |
| [3] | Zhu Y N, Cui L J, Li J, et al. Long-term performance of nutrient removal in an integrated constructed wetland[J]. Science of the Total Environment, 2021, 779. DOI:10.1016/j.scitotenv.2021.146268 |
| [4] | Jia Y Q, Sun S H, Wang S, et al. Phosphorus in water: a review on the speciation analysis and species specific removal strategies[J]. Critical Reviews in Environmental Science and Technology, 2023, 53(4): 435-456. DOI:10.1080/10643389.2022.2068362 |
| [5] | Ramasahayam S K, Guzman L, Gunawan G, et al. A comprehensive review of phosphorus removal technologies and processes[J]. Journal of Macromolecular Science, Part A, 2014, 51(6): 538-545. DOI:10.1080/10601325.2014.906271 |
| [6] | Salah M, Zheng Y, Wang Q, et al. Insight into pharmaceutical and personal care products removal using constructed wetlands: a comprehensive review[J]. Science of the Total Environment, 2023, 885. DOI:10.1016/j.scitotenv.2023.163721 |
| [7] | Li Q Z, Guo Y, Yu J Q, et al. Construction of hybrid constructed wetlands for phosphorus chemical industry tailwater treatment in the middle Yangtze River Basin: responses of plant growth and root-associated microbial communities[J]. Water Biology and Security, 2023, 2(3). DOI:10.1016/j.watbs.2023.100144 |
| [8] | Fan Y Y, Sun S S, He S B. Iron plaque formation and its effect on key elements cycling in constructed wetlands: functions and outlooks[J]. Water Research, 2023, 235. DOI:10.1016/j.watres.2023.119837 |
| [9] | Hiley P D. The reality of sewage treatment using wetlands[J]. Water Science and Technology, 1995, 32(3): 329-338. DOI:10.2166/wst.1995.0155 |
| [10] | Ji Z H, Tang W Z, Pei Y S. Constructed wetland substrates: a review on development, function mechanisms, and application in contaminants removal[J]. Chemosphere, 2022, 286. DOI:10.1016/j.chemosphere.2021.131564 |
| [11] | Bassin J P, Kleerebezem R, Dezotti M, et al. Simultaneous nitrogen and phosphate removal in aerobic granular sludge reactors operated at different temperatures[J]. Water Research, 2012, 46(12): 3805-3816. DOI:10.1016/j.watres.2012.04.015 |
| [12] | Li J, Liu L, Zheng Y M, et al. Influence of plants on anammox process in constructed wetland: irrelevance, inhibition or enhancement[J]. Chemical Engineering Journal, 2023, 460. DOI:10.1016/j.cej.2023.141619 |
| [13] | Liu Y, Liu X H, Li K, et al. Removal of nitrogen from low pollution water by long-term operation of an integrated vertical-flow constructed wetland: performance and mechanism[J]. Science of the Total Environment, 2019, 652: 977-988. DOI:10.1016/j.scitotenv.2018.10.313 |
| [14] | Kulshreshtha N M, Verma V, Soti A, et al. Exploring the contribution of plant species in the performance of constructed wetlands for domestic wastewater treatment[J]. Bioresource Technology Reports, 2022, 18. DOI:10.1016/j.biteb.2022.101038 |
| [15] | Yang X, Arias M E, Ergas S J. Hybrid constructed wetlands amended with zeolite/biochar for enhanced landfill leachate treatment[J]. Ecological Engineering, 2023, 192. DOI:10.1016/j.ecoleng.2023.106990 |
| [16] | Nocetti E, Hadad H R, Di Luca G A, et al. Pollutant removal modeling in a hybrid wetland system for industrial wastewater treatment[J]. Journal of Water Process Engineering, 2023, 53. DOI:10.1016/j.jwpe.2023.103794 |
| [17] |
杨长明, 张翔, 郝彦璋, 等. 人工湿地污水生态处理技术研究现状、挑战与展望[J]. 工业水处理, 2021, 41(9): 18-25. Yang C M, Zhang X, Hao Y Z, et al. Research status, challenges and prospects of constructed wetland technology for wastewater ecological treatment[J]. Industrial Water Treatment, 2021, 41(9): 18-25. |
| [18] | Verma V, Soti A, Kulshreshtha N M, et al. Strategies for enhancing phosphorous removal in vertical flow constructed wetlands[J]. Journal of Environmental Management, 2022, 317. DOI:10.1016/j.jenvman.2022.115406 |
| [19] | Yang C, Zhang X L, Tang Y Q, et al. Selection and optimization of the substrate in constructed wetland: a review[J]. Journal of Water Process Engineering, 2022, 49. DOI:10.1016/j.jwpe.2022.103140 |
| [20] | Maucieri C, Salvato M, Borin M. Vegetation contribution on phosphorus removal in constructed wetlands[J]. Ecological Engineering, 2020, 152. DOI:10.1016/j.ecoleng.2020.105853 |
| [21] | Gu X S, Peng Y Y, Sun S S, et al. Simultaneous denitrification and iron-phosphorus precipitation driven by plant biomass coupled with iron scraps in subsurface flow constructed wetlands[J]. Journal of Environmental Management, 2022, 322. DOI:10.1016/j.jenvman.2022.116104 |
| [22] | Liang M Y, Han Y C, Easa S M, et al. New solution to build constructed wetland in cold climatic region[J]. Science of the Total Environment, 2020, 719. DOI:10.1016/j.scitotenv.2020.137124 |
| [23] | Wang S K, Wang R M, Vymazal J, et al. Shifts of active microbial community structure and functions in constructed wetlands responded to continuous decreasing temperature in winter[J]. Chemosphere, 2023, 335. DOI:10.1016/j.chemosphere.2023.139080 |
| [24] | Kadlec R H. Comparison of free water and horizontal subsurface treatment wetlands[J]. Ecological Engineering, 2009, 35(2): 159-174. DOI:10.1016/j.ecoleng.2008.04.008 |
| [25] | Ge Z B, Wei D Y, Zhang J, et al. Natural pyrite to enhance simultaneous long-term nitrogen and phosphorus removal in constructed wetland: three years of pilot study[J]. Water Research, 2019, 148: 153-161. DOI:10.1016/j.watres.2018.10.037 |
| [26] | Hou X X, Chu L L, Wang Y F, et al. Microelectrolysis-integrated constructed wetland with sponge iron filler to simultaneously enhance nitrogen and phosphorus removal[J]. Bioresource Technology, 2023, 384. DOI:10.1016/j.biortech.2023.129270 |
| [27] | Gupta S, Srivastava P, Patil S A, et al. A comprehensive review on emerging constructed wetland coupled microbial fuel cell technology: potential applications and challenges[J]. Bioresource Technology, 2021, 320. DOI:10.1016/j.biortech.2020.124376 |
| [28] | Wang Y M, Lin Z Y, Wang Y, et al. Sulfur and iron cycles promoted nitrogen and phosphorus removal in electrochemically assisted vertical flow constructed wetland treating wastewater treatment plant effluent with high S/N ratio[J]. Water Research, 2019, 151: 20-30. DOI:10.1016/j.watres.2018.12.005 |
| [29] |
谭心, 邹晓凤, 苏强, 等. 污水处理厂尾水深度除磷技术综述[J]. 山东化工, 2021, 50(16): 277-279. Tan X, Zuo X F, Su Q, et al. A review of advanced phosphorus removal technology in the tail water of sewage treatment plant[J]. Shandong Chemical Industry, 2021, 50(16): 277-279. DOI:10.3969/j.issn.1008-021X.2021.16.112 |
| [30] | Jia C H, Chi J L, Zhang W J. Adsorption effects and mechanisms of phosphorus by nanosized laponite[J]. Chemosphere, 2023, 331. DOI:10.1016/j.chemosphere.2023.138684 |
| [31] | Zhou M, Cao J S, Lu Y H, et al. The performance and mechanism of iron-modified aluminum sludge substrate tidal flow constructed wetlands for simultaneous nitrogen and phosphorus removal in the effluent of wastewater treatment plants[J]. Science of the Total Environment, 2022, 847. DOI:10.1016/j.scitotenv.2022.157569 |
| [32] | Shang Z X, Wang Y R, Wang S Q, et al. Enhanced phosphorus removal of constructed wetland modified with novel Lanthanum-ammonia-modified hydrothermal biochar: performance and mechanism[J]. Chemical Engineering Journal, 2022, 449. DOI:10.1016/j.cej.2022.137818 |
| [33] | Gao Y, Zhang W, Gao B, et al. Highly efficient removal of nitrogen and phosphorus in an electrolysis-integrated horizontal subsurface-flow constructed wetland amended with biochar[J]. Water Research, 2018, 139: 301-310. DOI:10.1016/j.watres.2018.04.007 |
| [34] | Xu R, Zhang Y, Liu R, et al. Effects of different substrates on nitrogen and phosphorus removal in horizontal subsurface flow constructed wetlands[J]. Environmental Science and Pollution Research, 2019, 26(16): 16229-16238. DOI:10.1007/s11356-019-04945-1 |
| [35] | Wang Q, Hu Y B, Xie H J, et al. Constructed wetlands: a review on the role of radial oxygen loss in the rhizosphere by macrophytes[J]. Water, 2018, 10(6). DOI:10.3390/w10060678 |
| [36] | Lu B, Xu Z S, Li J G, et al. Removal of water nutrients by different aquatic plant species: an alternative way to remediate polluted rural rivers[J]. Ecological Engineering, 2018, 110: 18-26. DOI:10.1016/j.ecoleng.2017.09.016 |
| [37] |
张明珍, 曹涛涛, 刘伟, 等. 水平潜流人工湿地堵塞初期微生物群落结构变化[J]. 水生生物学报, 2022, 46(10): 1510-1517. Zhang M Z, Cao T T, Liu W, et al. Microbial community structure during the initial clogging stage in horizontal subsurface flow constructed wetlands[J]. Acta Hydrobiologica Sinica, 2022, 46(10): 1510-1517. DOI:10.7541/2022.2021.027 |
| [38] | Wang H X, Sheng L X, Xu J L. Clogging mechanisms of constructed wetlands: a critical review[J]. Journal of Cleaner Production, 2021, 295. DOI:10.1016/j.jclepro.2021.126455 |
| [39] | Hu Z Q, Chu Y, Ma Y H. Design of a combined constructed wetland system and its application on swine wastewater treatment[J]. Journal of Environmental Engineering, 2020, 146(1). DOI:10.1061/(asce)ee.1943-7870.0001602 |
| [40] |
谢志刚, 邱雪敏, 赵燕玲. 间歇式气水联合反冲洗生物炭池的试验研究[J]. 环境科学, 2012, 33(1): 124-128. Xie Z G, Qiu X M, Zhao Y L. Experimental research on combined water and air backwashing reactor technology for biological activated carbon[J]. Environmental Science, 2012, 33(1): 124-128. DOI:10.13227/j.hjkx.2012.01.029 |
| [41] | Penn C, Chagas I, Klimeski A, et al. A review of phosphorus removal structures: how to assess and compare their performance[J]. Water, 2017, 9(8). DOI:10.3390/w9080583 |
| [42] | Kasak K, Valach A C, Rey-Sanchez C, et al. Experimental harvesting of wetland plants to evaluate trade-offs between reducing methane emissions and removing nutrients accumulated to the biomass in constructed wetlands[J]. Science of the Total Environment, 2020, 715. DOI:10.1016/j.scitotenv.2020.136960 |
| [43] |
李龙山, 倪细炉, 李志刚, 等. 5种湿地植物对生活污水净化效果研究[J]. 西北植物学报, 2013, 33(11): 2292-2300. Li L S, Ni X L, Li Z G, et al. Sewage cleaning abilities of five wetland plants[J]. Acta Botanica Boreali-Occidentalia Sinica, 2013, 33(11): 2292-2300. DOI:10.7606/j.issn.1000-4025.2013.11.2292 |
| [44] |
卫小松, 夏品华, 袁果, 等. 湿地植物对富营养化水体中氮磷的吸收及去除贡献[J]. 西南农业学报, 2016, 29(2): 408-412. Wei X S, Xia P H, Yuan G, et al. Absorption capacity and removal contribution of wetland plants to nitrogen and phosphorus in eutrophic water body[J]. Southwest China Journal of Agricultural Sciences, 2016, 29(2): 408-412. |
| [45] | Ruan W F, Cai H B, Xu X M, et al. Efficiency and plant indication of nitrogen and phosphorus removal in constructed wetlands: a field-scale study in a frost-free area[J]. Science of the Total Environment, 2021, 799. DOI:10.1016/j.scitotenv.2021.149301 |
| [46] | Zhang J, Sun H M, Wang W G, et al. Enhancement of surface flow constructed wetlands performance at low temperature through seasonal plant collocation[J]. Bioresource Technology, 2017, 224: 222-228. DOI:10.1016/j.biortech.2016.11.006 |
| [47] |
廖德润, 林国徐, 王振, 等. 植物收割频率对水生植物滤床深度处理养猪废水的影响[J]. 环境工程学报, 2013, 7(12): 4793-4798. Liao D R, Lin G X, Wang Z, et al. Effect of cutting frequency on tertiary treatment of swine wastewater using aquatic plant filter bed system[J]. Chinese Journal of Environmental Engineering, 2013, 7(12): 4793-4798. |
| [48] |
赵梦云, 熊家晴, 郑于聪, 等. 植物收割对人工湿地中污染物去除的长期影响[J]. 水处理技术, 2019, 45(11): 112-116. Zhao M Y, Xiong J Q, Zheng Y C, et al. Long-term effect of plant harvesting on pollutants removal in constructed wetlands[J]. Technology of Water Treatment, 2019, 45(11): 112-116. |
| [49] |
叶磊, 李希, 田日昌, 等. 不同植物组合人工湿地中磷去向特征研究[J]. 农业环境科学学报, 2020, 39(10): 2409-2419. Ye L, Li X, Tian R C, et al. Characteristics of phosphorus fate in constructed wetlands with different plant combinations[J]. Journal of Agro-Environment Science, 2020, 39(10): 2409-2419. DOI:10.11654/jaes.2020-0761 |
| [50] | Han C, Wang Z, Wu Q Q, et al. Evaluation of the role of inherent Ca2+ in phosphorus removal from wastewater system[J]. Water Science and Technology, 2016, 73(7): 1644-1651. DOI:10.2166/wst.2015.642 |
| [51] | Zhang J J, Zhao X, Wang Y, et al. Recovery of phosphorus from hypophosphite-laden wastewater: a single-compartment photoelectrocatalytic cell system integrating oxidation and precipitation[J]. Environmental Science & Technology, 2020, 54(2): 1204-1213. |
| [52] | Shen Y H, Zhuang L L, Zhang J, et al. A study of ferric-carbon micro-electrolysis process to enhance nitrogen and phosphorus removal efficiency in subsurface flow constructed wetlands[J]. Chemical Engineering Journal, 2019, 359: 706-712. DOI:10.1016/j.cej.2018.11.152 |
| [53] | Strang T J, Wareham D G. Phosphorus removal in a waste-stabilization pond containing limestone rock filters[J]. Journal of Environmental Engineering and Science, 2006, 5(6): 447-457. DOI:10.1139/s06-017 |
| [54] | Zeng W S, Wang D H, Luo Z F, et al. Phosphorus recovery from pig farm biogas slurry by the catalytic ozonation process with MgO as the catalyst and magnesium source[J]. Journal of Cleaner Production, 2020, 269. DOI:10.1016/j.jclepro.2020.122133 |
| [55] | Leng C P, Yuan Y G, Zhang Z Y, et al. Decomposition of phosphorus pollution and microorganism analysis using novel CW-MFCs under different influence factors[J]. Molecules, 2023, 28(5). DOI:10.3390/MOLECULES28052124 |
| [56] | Hu X J, Wan X D, Tan W, et al. More is better? Constructed wetlands filled with different amount of Fe oxides showed opposite phosphorus removal performance[J]. Journal of Cleaner Production, 2021, 329. DOI:10.1016/j.jclepro.2021.129749 |
| [57] | Nguyen T A H, Ngo H H, Guo W S, et al. White hard clam (Meretrix lyrata) shells media to improve phosphorus removal in lab-scale horizontal sub-surface flow constructed wetlands: performance, removal pathways, and lifespan[J]. Bioresource Technology, 2020, 312. DOI:10.1016/j.biortech.2020.123602 |
| [58] | Wang S H, Yang H R, Che F F, et al. Removal efficacy of fly ash composite filler on tailwater nitrogen and phosphorus and its application in constructed wetlands[J]. Frontiers in Chemistry, 2023, 11. DOI:10.3389/fchem.2023.1160489 |
| [59] | Li Y J, Wang J P, Lin X C, et al. Purification effects of recycled aggregates from construction waste as constructed wetland filler[J]. Journal of Water Process Engineering, 2022, 50. DOI:10.1016/j.jwpe.2022.103335 |
| [60] | Wang G H, Gao J Q, Yang R X, et al. Preparation of sustainable non-combustion filler substrate from waterworks sludge/aluminum slag/gypsum/silica/maifan stone for phosphorus immobilization in constructed wetlands[J]. Water Science and Technology, 2019, 80(1): 153-163. DOI:10.2166/wst.2019.258 |
| [61] | Li Q, Zhang J S, Gao J Q, et al. Preparation of a novel non-burning polyaluminum chloride residue(PACR) compound filler and its phosphate removal mechanisms[J]. Environmental Science and Pollution Research, 2022, 29(1): 1532-1545. DOI:10.1007/s11356-021-15724-2 |
| [62] | Zeng Y J, Xu W B, Wang H, et al. Nitrogen and phosphorus removal efficiency and denitrification kinetics of different substrates in constructed wetland[J]. Water, 2022, 14(11). DOI:10.3390/w14111757 |
| [63] | Kõiv-Vainik M, Kriipsalu M, Vohla C, et al. Hydrated oil shale ash and mineralized peat as alternative filter materials for landfill leachate treatment in vertical flow constructed wetlands[J]. Fresenius Environmental Bulletin, 2009, 18(2): 189-195. |
| [64] | Jóźwiakowski K, Gajewska M, Pytka A, et al. Influence of the particle size of carbonate-siliceous rock on the efficiency of phosphorous removal from domestic wastewater[J]. Ecological Engineering, 2017, 98: 290-296. DOI:10.1016/j.ecoleng.2016.11.006 |
| [65] | Lu S B, Zhang X L, Wang J H, et al. Impacts of different media on constructed wetlands for rural household sewage treatment[J]. Journal of Cleaner Production, 2016, 127: 325-330. DOI:10.1016/j.jclepro.2016.03.166 |
| [66] | Liu M, Chen Y Y, Wu Y D, et al. Synergistic action of plants and microorganism in integrated floating bed on eutrophic brackish water purification in coastal estuary areas[J]. Frontiers in Marine Science, 2021, 8. DOI:10.3389/fmars.2021.619087 |
| [67] | Yang X G, Li Y, Kong F L, et al. Effect of ZnFe-LDHs modified oyster shell on the removal of tetracyclines antibiotics and variation of tet genes in vertical flow constructed wetlands[J]. Chemical Engineering Journal, 2022, 431. DOI:10.1016/j.cej.2021.134093 |
| [68] | Yan J, Hu X B, He Q, et al. Simultaneous enhancement of treatment performance and energy recovery using pyrite as anodic filling material in constructed wetland coupled with microbial fuel cells[J]. Water Research, 2021, 201. DOI:10.1016/j.watres.2021.117333 |
| [69] | Shi X, Fan J L, Zhang J, et al. Enhanced phosphorus removal in intermittently aerated constructed wetlands filled with various construction wastes[J]. Environmental Science and Pollution Research, 2017, 24(28): 22524-22534. DOI:10.1007/s11356-017-9870-z |
| [70] | Zhang X M, Wang T T, Xu Z J, et al. Effect of heavy metals in mixed domestic-industrial wastewater on performance of recirculating standing hybrid constructed wetlands (RSHCWs) and their removal[J]. Chemical Engineering Journal, 2020, 379. DOI:10.1016/j.cej.2019.122363 |
| [71] | Wan Z F, Zhang Y R, Lu S Y, et al. Effect of packing substrates on the purification of municipal wastewater treatment plant effluent[J]. Environmental Science and Pollution Research, 2020, 27(13): 15259-15266. DOI:10.1007/s11356-020-08068-w |
| [72] | Zhang X L, Chen Q Z, Guo L, et al. Effects of varying particle sizes and different types of LDH-Modified anthracite in simulated test columns for phosphorous removal[J]. International Journal of Environmental Research and Public Health, 2015, 12(6): 6788-6800. DOI:10.3390/ijerph120606788 |
| [73] | Kasak K, Truu J, Ostonen I, et al. Biochar enhances plant growth and nutrient removal in horizontal subsurface flow constructed wetlands[J]. Science of the Total Environment, 2018, 639: 67-74. DOI:10.1016/j.scitotenv.2018.05.146 |
| [74] | Deng S J, Chen J Q, Chang J J. Application of biochar as an innovative substrate in constructed wetlands/biofilters for wastewater treatment: performance and ecological benefits[J]. Journal of Cleaner Production, 2021, 293. DOI:10.1016/j.jclepro.2021.126156 |
| [75] | Ramdat N, Wang Z J, Huang J C, et al. Effects of enrofloxacin on nutrient removal by a floating treatment wetland planted with Iris pseudacorus: response and resilience of rhizosphere microbial communities[J]. Sustainability, 2022, 14(6). DOI:10.3390/su14063358 |
| [76] | Li L Y, Feng J W, Zhang L, et al. Enhanced nitrogen and phosphorus removal by natural pyrite–based constructed wetland with intermittent aeration[J]. Environmental Science and Pollution Research, 2021, 28(48): 69012-69028. DOI:10.1007/s11356-021-15461-6 |
| [77] | Bawiec A. Efficiency of nitrogen and phosphorus compounds removal in hydroponic wastewater treatment plant[J]. Environmental Technology, 2019, 40(16): 2062-2072. DOI:10.1080/09593330.2018.1436595 |
| [78] | Zhang J Y, Shao Z Y, Li B, et al. Root vertical spatial stress: a method for enhancing rhizosphere effect of plants in subsurface flow constructed wetland[J]. Environmental Research, 2023, 231. DOI:10.1016/j.envres.2023.116083 |
| [79] | Li L, Feng Y, Li J Y, et al. Purification efficiency of eight aquatic plant species in an artificial floating island system in relation to extracellular enzyme activity and microbial community[J]. Environmental Engineering Research, 2022, 27(6). DOI:10.4491/eer.2021.443 |
| [80] | Liu W, Chu Y F, Tan Q Y, et al. Cold temperature mediated nitrate removal pathways in electrolysis-assisted constructed wetland systems under different influent C/N ratios and anode materials[J]. Chemosphere, 2022, 295. DOI:10.1016/j.chemosphere.2022.133867 |
| [81] | Di Luca G A, Mufarrege M M, Hadad H R, et al. Nitrogen and phosphorus removal and Typha domingensis tolerance in a floating treatment wetland[J]. Science of the Total Environment, 2019, 650: 233-240. DOI:10.1016/j.scitotenv.2018.09.042 |
| [82] | Lu X M, Huang M S. Nitrogen and phosphorus removal and physiological response in aquatic plants under aeration conditions[J]. International Journal of Environmental Science & Technology, 2010, 7(4): 665-674. |
| [83] | Baldovi A A, de Barros Aguiar A R, Benassi R F, et al. Phosphorus removal in a pilot scale free water surface constructed wetland: hydraulic retention time, seasonality and standing stock evaluation[J]. Chemosphere, 2021, 266. DOI:10.1016/j.chemosphere.2020.128939 |
| [84] | Shen S T, Li X, Dai Z Q, et al. Floating treatment wetland integrated with sediment microbial fuel cell for low-strength surface water treatment[J]. Journal of Cleaner Production, 2022, 374. DOI:10.1016/j.jclepro.2022.134002 |
| [85] | Aqdas A, Hashmi I. Role of water hyacinth (Eichhornia crassipes) in integrated constructed wetlands: a review on its phytoremediation potential[J]. International Journal of Environmental Science and Technology, 2023, 20(2): 2259-2266. DOI:10.1007/s13762-022-04181-0 |
| [86] | Imron M F, Firdaus A A F, Flowerainsyah Z O, et al. Phytotechnology for domestic wastewater treatment: performance of Pistia stratiotes in eradicating pollutants and future prospects[J]. Journal of Water Process Engineering, 2023, 51. DOI:10.1016/j.jwpe.2022.103429 |
| [87] | Zhou X Q, Li Z F, Zhao R X, et al. Experimental comparisons of three submerged plants for reclaimed water purification through nutrient removal[J]. Desalination and Water Treatment, 2016, 57(26): 12037-12046. DOI:10.1080/19443994.2015.1048736 |
| [88] | Zheng C Q, Zhang X W, Gan L, et al. Effects of biochar on the growth of Vallisneria natans in surface flow constructed wetland[J]. Environmental Science and Pollution Research, 2021, 28(46): 66158-66170. DOI:10.1007/s11356-021-15399-9 |
| [89] | Liu Y, Wei L C, Yu H W, et al. Negative impacts of nanoplastics on the purification function of submerged plants in constructed wetlands: responses of oxidative stress and metabolic processes[J]. Water Research, 2022, 227. DOI:10.1016/j.watres.2022.119339 |
| [90] | Hendriks L, Smolders A J P, van den Brink T, et al. Polishing wastewater effluent using plants: floating plants perform better than submerged plants in both nutrient removal and reduction of greenhouse gas emission[J]. Water Science and Technology, 2023, 88(1): 23-34. DOI:10.2166/wst.2023.203 |
| [91] | Zhu L Q, Zhang H K, Li Y P, et al. Evaluation of the optimization effect of a combined constructed wetland with micro-polluted water sources[J]. Journal of Water Process Engineering, 2022, 49. DOI:10.1016/j.jwpe.2022.103139 |
| [92] | Feng J W, Cui B H, Yuan B X, et al. Purification mechanism of low-pollution water in three submerged plants and analysis of bacterial community structure in plant rhizospheres[J]. Environmental Engineering Science, 2020, 37(8): 560-571. DOI:10.1089/ees.2019.0459 |
| [93] | Gao J Q, Li Q, Zhang J S, et al. Purification of micro-polluted lake water by biofortification of vertical subsurface flow constructed wetlands in low-temperature season[J]. Water, 2022, 14(6). DOI:10.3390/w14060896 |
| [94] | Chen X, Zhu H, Yan B X, et al. Greenhouse gas emissions and wastewater treatment performance by three plant species in subsurface flow constructed wetland mesocosms[J]. Chemosphere, 2020, 239. DOI:10.1016/j.chemosphere.2019.124795 |
| [95] | Li X H, Zhu W G, Meng G J, et al. Efficiency and kinetics of conventional pollutants and tetracyclines removal in integrated vertical-flow constructed wetlands enhanced by aeration[J]. Journal of Environmental Management, 2020, 273. DOI:10.1016/j.jenvman.2020.111120 |
| [96] | Liu J W, Wei Z R, Xu S, et al. A novel enhanced bio-ecological combined reactor for rural wastewater treatment: operational performance and microbial communities[J]. Biochemical Engineering Journal, 2023, 198. DOI:10.1016/j.bej.2023.108991 |
| [97] | Chen X R, Sun X L, Xu P, et al. Optimal regulation of N/P in horizontal sub-surface flow constructed wetland through quantitative phosphorus removal by steel slag fed[J]. Environmental Science and Pollution Research, 2020, 27(6): 5779-5787. DOI:10.1007/s11356-019-06696-5 |
| [98] | Gupta S, Srivastava P, Yadav A K. Simultaneous removal of organic matters and nutrients from high-strength wastewater in constructed wetlands followed by entrapped algal systems[J]. Environmental Science and Pollution Research, 2020, 27(1): 1112-1117. DOI:10.1007/s11356-019-06896-z |
| [99] | Nguyen T D P, Tran T N T, Le T V A, et al. Auto-flocculation through cultivation of Chlorella vulgaris in seafood wastewater discharge: influence of culture conditions on microalgae growth and nutrient removal[J]. Journal of Bioscience and Bioengineering, 2019, 127(4): 492-498. DOI:10.1016/j.jbiosc.2018.09.004 |
| [100] | De Souza Celente G, Colares G S, Machado Ê L, et al. Algae turf scrubber and vertical constructed wetlands combined system for decentralized secondary wastewater treatment[J]. Environmental Science and Pollution Research, 2019, 26(10): 9931-9937. DOI:10.1007/s11356-019-04425-6 |
| [101] | Wang S Y, Teng Y F, Cheng F K, et al. Application potential of constructed wetlands on different operation mode for biologically pre-treatment of rural domestic wastewater[J]. Sustainability, 2023, 15(3). DOI:10.3390/su15031799 |
| [102] | Rezania S, Kamyab H, Rupani P F, et al. Recent advances on the removal of phosphorus in aquatic plant-based systems[J]. Environmental Technology & Innovation, 2021, 24. DOI:10.1016/j.eti.2021.101933 |
| [103] | Li J F, Wang Y H, Cui J W, et al. Removal effects of aquatic plants on high-concentration phosphorus in wastewater during summer[J]. Journal of Environmental Management, 2022, 324. DOI:10.1016/j.jenvman.2022.116434 |
| [104] | Carrillo V, Gómez G, Vidal G. Phosphorus uptake by macrophyte plants in monocultures and polycultures in constructed wetlands for wastewater treatment[J]. Ecological Engineering, 2022, 182. DOI:10.1016/j.ecoleng.2022.106690 |
| [105] | Chen P Z, Zheng X Q, Ren T Z, et al. Vertical flow artificial wetland system of waste bricks removes phosphorus in rural domestic wastewater and phosphorus transport characteristics[J]. Fresenius Environmental Bulletin, 2017, 26(12): 7411-7418. |
| [106] | Luo Y M, Chen Q, Liu F, et al. Both species richness and growth forms affect nutrient removal in constructed wetlands: a mesocosm experiment[J]. Frontiers in Ecology and Evolution, 2023, 11. DOI:10.3389/fevo.2023.1139053 |
| [107] | Liang Y X, Zhu H, Bañuelos G, et al. Removal of nutrients in saline wastewater using constructed wetlands: plant species, influent loads and salinity levels as influencing factors[J]. Chemosphere, 2017, 187: 52-61. DOI:10.1016/j.chemosphere.2017.08.087 |
| [108] | Jiang S J, Xu J L, Wang H X, et al. Study of the effect of pyrite and alkali-modified rice husk substrates on enhancing nitrogen and phosphorus removals in constructed wetlands[J]. Environmental Science and Pollution Research, 2022, 29(36): 54234-54249. DOI:10.1007/s11356-022-19537-9 |
| [109] | Li Q, Gao J Q, Zhang J S, et al. Treatment of high-phosphorus load wastewater by column packed with non-burning compound filler/gravel/ceramsite: evaluation of performance and microorganism community[J]. Environmental Science and Pollution Research, 2023, 30(25): 67730-67741. DOI:10.1007/s11356-023-26487-3 |
| [110] | Wang J, Gu Y G, Wang H, et al. Investigation on the treatment effect of slope wetland on pollutants under different hydraulic retention times[J]. Environmental Science and Pollution Research, 2021, 28(8): 9107-9119. DOI:10.1007/s11356-020-11292-z |
| [111] | Tao Z K, Jing Z Q, Tao M N, et al. Advanced treatment of sewage plant effluent by horizontal subsurface flow constructed wetlands: effect of coupling with cellulosic carbon sources[J]. Desalination and Water Treatment, 2020, 189: 53-65. DOI:10.5004/dwt.2020.25478 |
| [112] | Wang Z, Dong J, Liu L, et al. Screening of phosphate-removing substrates for use in constructed wetlands treating swine wastewater[J]. Ecological Engineering, 2013, 54: 57-65. DOI:10.1016/j.ecoleng.2013.01.017 |
| [113] | Parastesh F, Alikhani H A, Etesami H. Vermicompost enriched with phosphate–solubilizing bacteria provides plant with enough phosphorus in a sequential cropping under calcareous soil conditions[J]. Journal of Cleaner Production, 2019, 221: 27-37. DOI:10.1016/j.jclepro.2019.02.234 |
| [114] | Wang Q, Ding J W, Xie H J, et al. Phosphorus removal performance of microbial-enhanced constructed wetlands that treat saline wastewater[J]. Journal of Cleaner Production, 2021, 288. DOI:10.1016/j.jclepro.2020.125119 |
| [115] | Tan X, Yang Y L, Li X, et al. Multi-metabolism regulation insights into nutrients removal performance with adding heterotrophic nitrification-aerobic denitrification bacteria in tidal flow constructed wetlands[J]. Science of the Total Environment, 2021, 796. DOI:10.1016/j.scitotenv.2021.149023 |
| [116] | Tian L P, Yan B X, Ou Y, et al. Effectiveness of exogenous Fe2+ on nutrient removal in gravel-based constructed wetlands[J]. International Journal of Environmental Research and Public Health, 2022, 19(3). DOI:10.3390/ijerph19031475 |
| [117] | Whitfield C J, Casson N J, North R L, et al. The effect of freeze-thaw cycles on phosphorus release from riparian macrophytes in cold regions[J]. Canadian Water Resources Journal, 2019, 44(2): 160-173. DOI:10.1080/07011784.2018.1558115 |
| [118] | Pavlidis G, Zotou I, Karasali H, et al. Performance of pilot-scale constructed floating wetlands in the removal of nutrients and pesticides[J]. Water Resources Management, 2022, 36(1): 399-416. DOI:10.1007/s11269-021-03033-9 |
| [119] | Zhu H, Zhou Q W, Yan B X, et al. Influence of vegetation type and temperature on the performance of constructed wetlands for nutrient removal[J]. Water Science and Technology, 2018, 77(3): 829-837. DOI:10.2166/wst.2017.556 |
| [120] | Zheng Y C, Yang D, Dzakpasu M, et al. Effects of plants competition on critical bacteria selection and pollutants dynamics in a long-term polyculture constructed wetland[J]. Bioresource Technology, 2020, 316. DOI:10.1016/j.biortech.2020.123927 |
| [121] | Zhang R, Liu X C, Wang L T, et al. Combining a novel biofilm reactor with a constructed wetland for rural, decentralized wastewater treatment[J]. Chemical Engineering Journal, 2023, 455. DOI:10.1016/j.cej.2022.140906 |
| [122] | Chen P P, Yu X F, Zhang J Y. Photocatalysis enhanced constructed wetlands effectively remove antibiotic resistance genes from domestic wastewater[J]. Chemosphere, 2023, 325. DOI:10.1016/j.chemosphere.2023.138330 |
| [123] | Yang P F, Ge S H, Liu Z Q, et al. Optimization and mechanism of coupling process between algal ponds and constructed wetlands for wastewater polishing and nutrient recovery[J]. Journal of Cleaner Production, 2023, 389. DOI:10.1016/j.jclepro.2023.136057 |
| [124] | Wang T, Ni Z L, Kuang B, et al. Two-stage hybrid microalgal electroactive wetland-coupled anaerobic digestion for swine wastewater treatment in South China: full-scale verification[J]. Science of the Total Environment, 2022, 820. DOI:10.1016/j.scitotenv.2022.153312 |
| [125] | Zheng X Y, Zhou C, Wu F, et al. Enhanced removal of organic, nutrients, and PFCs in the iron-carbon micro-electrolysis constructed wetlands: mechanism and iron cycle[J]. Chemical Engineering Journal, 2023, 457. DOI:10.1016/j.cej.2022.141174 |
| [126] | Wang T, Zhou L L, Cai C L, et al. Electroactive bacteria–algae biofilm coupled with siphon aeration boosts high-salinity wastewater purification: a pilot study focusing on performance and microbial community[J]. Journal of Water Process Engineering, 2023, 53. DOI:10.1016/j.jwpe.2023.103841 |
| [127] | Zheng X Y, Jin M Q, Zhou X, et al. Enhanced removal mechanism of iron carbon micro-electrolysis constructed wetland on C, N, and P in salty permitted effluent of wastewater treatment plant[J]. Science of the Total Environment, 2019, 649: 21-30. DOI:10.1016/j.scitotenv.2018.08.195 |