复合生态床系统在农业面源污染治理中的应用研究

【作者】 吴献花；

【导师】 普红平； 李荫玺； 陈源高；

【作者基本信息】 昆明理工大学 ， 环境工程， 2004， 硕士

【摘要】 抚仙湖是我国第二深水湖泊，近年来出现了加速富营养化趋势，促进因素主要有外来污染增加，湖滨带遭到严重破坏，氮、磷等营养盐在湖内迅速积累，湖泊生态系统过于简单、脆弱等。调研发现，径流区高强度的农作和大量使用化肥农药、村落生活污水和垃圾等面源污染经入湖河流输入湖泊是引起抚仙湖富营养化加速发展的根本原因，因而入湖河流的减污控制是保护抚仙湖的关键。 抚仙湖的北岸是湖泊污染负荷的主要来源地。窑泥沟-农灌中沟是北岸污染最严重的河道，它汇集了径流区内20个村镇、4700多亩农田的面源污水，因此，窑泥沟-农灌中沟的减污是控制抚仙湖北部面源污染的关键。窑泥沟和农灌中沟两沟相矩50米，农灌中沟西侧有一22.5亩的荒废湖滩，清理整顿湖滩环境，建立由农灌中沟及窑泥沟的溢流堰、固体垃圾打捞平台及拦污网、生物强化沉淀调节池、氧化塘、水平潜流人工湿地、表面流人工湿地组成的面源污水复合生态床处理系统。系统设计处理规模4400m³／day，水力滞留时间51.8小时，则系统年污水处理量为160万吨，占窑泥沟污水总量的36.3％。 试验研究表明：系统以打捞的方式可年清除河道内各类垃圾750吨；在设计高水力负荷（44cm／d）条件下，生物强化沉淀调节池对SS、TN、TP和NH₃-N的平均去除率为61.8％、3.6％、5.9％、8.5％；氧化塘对SS、CODcr、TN、NH₃-N和TP去除率在20％～90.32％、34.55％～57.60％、-4.12％～42.53％、-28.75％～61.49％和-11.71％～35.77％之间，有二次污染现象存在；水平潜流人工湿地对CODcr、TN、NH₄⁺-N和TP去除率在9.10％～29.61％、5.60％～33.71％、2.41％～27.44％、1、1.19％～60.00％之间，不同的潜流湿地结构，氮、磷的去除效果不同，TN的平均去除顺序为炉渣+芦苇（30.17％）＞砾石（3－5cm）+伞竹+香蒲（25.94％）＞砾石（1-3cm）+芦苇（19.11％）＞公分石（2-4cm）+香蒲（18.22％），TP的平均去除顺序为砾石（3-5cm）+伞竹+香蒲（42.23％）＞炉渣+芦苇（36.19％）＞砾石（1-3cm）+芦苇（33.49％）＞公分石（3-5cm）+香蒲（21.14％）；地表流人工湿地对CODcr、TN、NH3-N和 TP 的去除率在30.29％～88.43％、21.80％～74.75％、22.33％～82.47％和16.54％～63.75％之间，平均去除率为50.99％、41.04％、59.00％和31.75％；系统依靠水生植物水芹菜、香蒲、芦苇、菱、荷的吸收作用去除的氮、磷量为6.05t／a和0.24t／a、0.14t／a和0.028t／a、0.02t／a和0.003t／a、1.01t／a和0.14t／a、0.12t／a和0.015t／a。经复合生态床污水处理系统处理后的出水的SS、BOD₅、CODcr、TN和TP浓度在0.8～10mg／l、3.0～5.3mg／l、4.1～24.5mg／l、0.9～10.4mg／l、0.2～0.98mg／l之间，工程验收达标率为100％、100％、100％、90.91％和72.73％，表面流人工湿地是该污水处理系统的主要净化单元，其次是氧化塘。 结论：在复合生态床污水处理系统中，各级单元床之间具有较强的互助和互补性，前面单元为后续单元提供了较好的前处理，使得后续单元能够较充分地发挥处理功效，同时由于系统结合了在厌氧、兼氧以及好氧状态下微生物、高等绿色植物根系、人工土壤的同化、分解、截流、吸收、吸附和过滤等处理机制，使得该系统具有高效的污水净化性能和较强的耐冲击负荷，且系统投资小、见效快、工艺简单、运行费用低、操作管理方便，只要在系统的前段增设贮水塘储存水量大、污染负荷严重时的来水，随后在间歇的流入该处理系统，这样，就可以缓解系统超负荷运行的不理想净化效果，还可增强系统的处理能力，适宜在湖滨带推广运用。更多还原

【Abstract】 Fuxian Lake, the second deepwater one in China, has shown a speeding nutrition-rich tendency in recent years, whose resulting factors include the increasing external pollution, the severe destruction in the lakeside zone, the quick accumulation of nutritive salts (such as N, P) in the lake and the simplicity & the weakness of the lake’s ecological system, etc. It has been found that the basic cause for the speeding nutrition-rich tendency lies in the non-point source pollutions within the lake’s runoff field (including the high-intensity cultivation, the mass-use of fertilizers pesticides, rural sewage & rubbish, etc.) which have been input into Fuxian Lake through some rivers, so the anti-pollution against these rivers is the key of protecting the lake.The main pollution source of Fuxian Lake is the northern bank whose severest pollution canal is Yaonigou-Nongguanzhonggou, which gathers all the non-point source wastewaters from twenty villages & small towns and more than 4700 mu farmlands in the runoff field. Therefore, the anti-pollution against Yaonigou-Nongguanzhonggou becomes the key to control the non-point source pollution in the northern part of Fuxian Lake. There is a distance of 50 meters between Yaonigou and Nongguanzhonggou. A 22.5-mu deserted lake beach in west of Nongguanzhonggou should be treated and then we could establish a non-point source wastewaters constructed wetland system which consists of Nongguanzhonggou, an overflow weir in Yaonigou, a solid rubbish salvaging platform, a waste boom, a precipitating adjustment tank, oxidation ponds, a subsurface flow artificial wetland and a free water system artificial wetland. Designed with a treatment scope of 4400 m3/day, the hydraulic retention time of 518 hours, this system could have a wastewater treatment capability of 1.6 million each year which counts for 36.2% of the total wastewater in Yaonigou.The results of our test research showed that this system could remove all kinds of 750-ton rubbish in the canals by means of salvaging each year. On the design condition of a high hydraulic load (44cm/d), 61.8% of SS, 3.6% of TN, 5.9% of TP and 8.5% of NH3-N could be removed through the precipitating adjustment tank; 20%-90.32% of SS, 34.55% -57.60% of CODcr, -4.12%-42.53% of TN, -28.75%-61.44% of NH3-N and -11.71%-35.77% of TP could be removed, but there exists a secondary pollution phenomenon through the oxidation ponds; 9.10%-29.61% of CODcr, 5.60%-33.71% of TN, 2.41%-27.44% of NH3-N and 11.19%-60.00% of TP could be removed through the subsurface flow artificial wetland and for differentsubsurface flow wetland structure, different N and P could be removed, TN has an average removing capability order of slag plus reed(30.17%) > big pebbles plus umbel bamboo plus cattail (25.94%) > pebbles plus reed (19.11%) > centimeter stones + cattail (18.22%) and TP has the order of pebbles plus umbel bamboo plus cattail (42.23%) > slag plus reed (36.19%) > small pebbles plus reed (33.49%) > centimeter stones plus cattail (21.14%) ; 30.29%-88.43%(average:50.99%) of CODcr, 21.80-74.75%(average:41.04%) of TN, 22.33%-83.47%(average:59.00%) of NH3-N and 16.54%-63.75%(average:31.75%) of TP could be removed through the free water system artificial "wetland; 6.05t/a, 0.14t/a, 0.02t/a, 1.01t/a 0.12t/a of N and 0.24t/a, 0.028t/a, 0.003t/a, 0.14t/a & 0.015t/a of P could be removed by the absorbing action of the system-depended plants such as water celery, cattail, reed, ling and lotus. The concentration of SS, BOD5, CODcr, TN and TP in the water treated by the constructed wetland system is 0.8-10mg/l, 4.1-24.5mg/l, 0.9-10.4mg/l & 0.2-0.98mg/l and the rate for the acceptance standard towards the project is up to 100%, 100%, 100%, 90.91 % and 72.73%.Conclusion: within the constructed wetland system, there are very strong inter-help and parataxis among the unit beds because the good pre-treatment of the former units lets the following nits able to make full use of their treatment functions. At the same time, this system has a high wastewater purification ability and a更多还原