Research on operation and management mode of treating domestic sewage with『Sewage Ecological Distribution and Treatment System』

• Main Authors: Lui Chai che, 劉嘉琪
• Other Authors: 沈建全
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/17327927489797087801

碩士 === 國立高雄海洋科技大學 === 海洋環境工程研究所 === 96 === In recent years, the government vigorously promoted river regulation, which has obviously improved the situation of industrial wastewater draining into rivers, however, due to inadequate fund for connecting enough sewage pipeline, it was difficult to accelerate the appropriate treatment of domestic sewage, which weakened the effect on river regulation, and made domestic sewage the major reason for the current river pollution. This research utilized flood land to conduct small-sized field experiment, and carried out the complex field and lab analyzing research on domestic sewage treatment based on the Sewage Ecological Distribution and Treatment System researched and developed by associate professor SHEN Jian-quan in the Department of Marine Environment Engineering, National Kaohsiung Marine University, in hope of using this system to improve the situation that domestic sewage was directly emitted into rivers, which resulted in river pollution, and to change people’s stereotype on flood land of being covered with ruderal, in order to enhance the self-treatment (cleaning) function of rivers, to create space for conservation, ecology, rest, and landscape, etc, and to come up with solutions to the current domestic lack of construction land for natural treatment engineering at the same time. This research used an aftereffect flood land to lay out 12 experiment lots with 6m in length and 2m in width, 6 lots of which were paved with tarpaulin at its surroundings and 30cm under the ground, while the other 6 lots of which were paved with nothing, by doing so, the comparison of whether it needs tarpaulin or not in the future implement of this system could be made. Besides, cattail, taro, pachyrhizus leaf, water spinach (or swamp cabbage), wild ginger lily (or butterfly ginger), and weed, were planted respectively on each lots, to compare the treating efficiency between plants (cattail) and economic crops (taro, pachyrhizus leaf, water spinach, wild ginger lily) which were often used to treat wastewater for common swamp, and compare it with the treating efficiency of weed, in order to provide reference for the future application of this system. This research, besides comparing the treating efficiency of various plants on Sewage Ecological Distribution and Treatment System, increased the amount of sewage entering this system to realize the purpose of increasing the total amount of pollution removal under the circumstance that the original water concentration could not be increased. Furthermore, this research discussed the treating effect when the water volume and the total amount of pollution increased, and appraised the feasibility of this system in future actual operation, and the extensibility of attracting populace to manage this system spontaneously, based on the yield of economic crops, yielding benefit, and correlation regulation, in expectation of planting crops with treating effect and attracting populace to spontaneously manage this system in the future operation of this system, in order to solve the current problem of lacking manpower for managing natural treatment projects. The result of water quality test indicated that the crops selected by this system had extreme good effect on treating domestic sewage, which was better than the effect of plants (cattail) chosen by common swamp and the original grass species growing on flood land. Among the economic crops, pachyrhizus leaf had the most remarkable treating effect, the COD treating capacity per day per unit area was 4.01g, that is, a 50% treating rate; the BOD treating capacity was 1.15 g, that is, a 35% treating rate; the TP treating capacity was 0.23 g, that is, a 16% treating rate; the TN treating capacity was 1.87 g, that is, a 74% treating rate; however, the treating effect decreased as the total amount of pollution entering this system increased by raising the water volume, which was mainly owing to the relatively short hydraulic retention time. We can set the increasing of treating area, hydraulic retention time, and influent density as the future researching direction, in order to enhance the treating effect of this system. As for the yielding benefits of crops in this system, the monthly market wholesale price of the economic crops grown on one hectare area of land could reach to around NTD 530 thousand. Moreover, the economic crops were able to meet the relevant requirements from Food Health Management Laws and Agricultural Production and Examination Laws in our country. Furthermore, as for the cropping pattern of this system, besides its easy culturing methods (no need for pumping irrigation), it did not need the use of pesticides, and the land condition used for this system was similar to common cultivated land (no need for tarpaulin), however, its crop yield was a little higher than common farmland. Comprehensive analysis: it is not necessary to equip this system with tarpaulin in the future. Besides, after this system has been brought into operation for 1 year, there was abundant ecology in the surroundings, and any ecological imbalance such as ecological singularization or species advantages has not happened due to the set-up of this system. There was a plant structure with 34 families and 87 species, an amphibian structure with 3 families and 4 species, a reptilian structure with 10 species, and a fish structure with 4 families and 8 species, and there were many birds flying close to or enter this system. Moreover, the dissolved oxygen capacity of the water treated by this system was higher than that of the in-flow water, which could improve the situation that lots of fishes were dying due to the decreasing of dissolved oxygen capacity and water volume in rivers. This sewage ecological distribution and treatment system has following advantages: 1. low construction costs, 2. energy-free, pesticide-free, 3. combining various ecological engineering methods, high treating efficiency, short hydraulic retention time, 4. producing edible crops, which generated considerable economic benefits and thus attracted populace to spontaneously manage this system, 5. easy to manage and maintain, 6. able to entrust farmers to manage and operate this system, 7. helpful to landscape ecology, 8. able to counteract flood.