Study On The Water Resource Optimal Disposal & Water Quality Protection Technique Measures In Longhu

To accelerate the urbanization, to spread the city frame, to advance the city classification, improve the living condition, to enhance the living quality, and to promote the economy development rapidly, Henan province and Zhengzhou city start to design building a new modernized area of¨beautiful water city¨- Zhengdongxinqu (ZDXQ) to the east of the old Zhengzhou city zone, with an area of 150 km2, which had the function of the ecology and the metabolism, and the Longhu lake would right be the eye of the new region.Longhu was a manmade lake with water area of 6.08km2, average water deep of 2.5m, and water volume of 1.5×107m3, with a scale of a middle sized reservoir. Longhu was a manmade lake system with multi-functions of city ecology, landscape travel, regional flooding control, and water resource integrated use and so on, which showed the theme of harmonious of nature and human beings, and the corresponding development of eco-environment and economic life. It was one of the biggest projects in the city developing layout of Zhengzhou city.It was indicated from the experience and the study that a big manmade lake would influence the local climate condition, hydraulic states and eco-environment in a certain degree. As Longhu was a important landscape and entertainment area, it was urgent to study on the eco-environment service value, the lake water quality and protection measures, water resource utilization of entering and exiting, and the study results would offer scientific study foundation and theoretical base to the optimal circle achievement of the Longhu water system in future.Based on the amount of literatures and references, and the analysis on related basic data, taking the building of ZDXQ and Longhu as the background, system study was mainly done on three points must take place during the building of Longhu, and they were ecology service (ES) value evaluation, technique protection measure and optimal disposal of water resources in Longhu. The research results were as following.1. Study on the ecology service valueThe outstanding character of the Longhu building design was the spirit of ES, so it was firstly screened out that 7 indexes that reflecting the ES value of Longhu the using the frequency analysis method, which included 4 indexes of direct using value as plant resource, entertainment culture, water supply and keep, and water purification, and 3 indexes of indirect using value as life-form variety, flood adjusting, and climate measurement. Then it was evaluated that the ES value of single index and the total in Longhu.The result showed that the ES value of Longhu was 1.1862×10~7yuan/a, the service value in unit area was 1.95×10~4yuan/ hm~2·a, which was obviously lower than the national lake ES value of 4.1×10~4yuan/ hm~2·a, while higher than the national ES value of 0.54×10~4yuan/ hm~2·a. As a manmade lake, Longhu was not perfect in its ecosystem. Since the water purifying function was relatively weak, and it was scare that the creatures and plants, it lost some service function of natural water out of the question, which should be perfected during the building and operating of it.In the total service value, the direct using value was 5.591×10~6yuan/a, and the indirect using value was 6.271×10~6yuan/a. Among the direct using value, entertainment culture occupied the biggest ratio, which showed the important of the function of Longhu landscape travel. In the Indirect UV, the highest value was on flooding control, accounting for 39.83%. Longhu was design to deal with the flood of century, at the same time, it was located in a special geographic position that colleting three rivers and one trench, even the yellow river recharged it indirectly, so it was very important that the ES function of flood control.The compare of Longhu to Baiyangdian and Zhalong marsh indicated that the ES value of Longhu was the lowest, which was only 1×10~7yuan/a, much smaller that the other two marsh. From the yearly service value in unit area, Longhu(1.95×10~4yuan/hm~2) was a bit lower than Baiyangdian (1.96×10~4yuan/hm~2), and Zhalong was the biggest of 5.1×10~4yuan/hm~2. Comparatively, as a manmade ecology project, Longhu was relatively perfect in ecology function so far, and showed the general ES function of marsh. The study result proved that the building theory of Longhu was right and scientific, which offered scientific base to the project building of Longhu, and provided precious reference value to the operation management of it as well.2. Study on the water quality protection technique measures in LonghuIt was the precondition that saving water resource by water recycling to achieve the sustainable development of economic benefit, environment benefit and society benefit. It was used that the three stages tandem aeration biology tank in the study, thereinto, the first two stages was in oxygenic condition, and the third stage was in anaerobic condition. The denitrification and dephosphorization experiments was done to the sanitary water to make the water out reach the demand quality for entering lake. The results demonstrated that the two stages oxygenic reactors had stable efficiency on decarburization and nitrification in suitable operating condition, and the water out could reach the demand of COD and ammonia when the condition was the best of the sieving speed of 0.5m/h, ratio of gas to water of 5:1. Taking the water out from the first two stages in best condition as the treating object, adding methanol, sodium acetate and dextrose as the carbon resource in addition into the third stage anaerobic reactor, the biological denitrification was obvious. When and the C/N was 3:1-4:1, the TN satisfied the water quality standard for entering lake. There was a certain degree of function of dephosphorization in the reactor, but the efficiency was relatively low.For example, when the carbon resource was sodium acetate, the sieving speed was 0.5m/h, the best dephosphorization rate was only 56.13% , and not so stable as biological denitrification. The simple biological dephosphorization could not meet the demand of TP for entering lake, so there must be chemical ways in addition for it.The results of series of chemical dephosphorization experiments showed that the best reagent for dephosphorization chemically was ferric chloride, and the best adding point was at the exit end of the third stage reactor. When the adding amount was 210mg/L, the water out satisfied the demand for entering lake.From the point of view of waste water reusing, dealing with the city sewage by the treating technique of three stages denitrification and dephosphorization, the water out could meet the demand on COD, TN and TP to enter lakes, which established a good base and presupposition to the later water resource optimal disposal in Longhu.3. Study on the water resource optimal disposalTo build such a big manmade lake, the distribution of the water in reason would directly influence the normal operation of the Longhu system in future, so scientific demonstrating and analyzing was necessary at the beginning of the Longhu building. At first, according to the current state of Zhengzhou city, ZDXQ and Longhu region, the usable water resource of Longhu could be Yellow River, Qialu River, groundwater, recycled water and rain. By the colligated analysis on the quantity and quality confirming of water in, the storage water resource was ascertained to be Yellow River, deeply treated waste water, ground water being pumped to decrease the groundwater level around the lake, which was mainly used for the recharge to the branches of Longhu to prevent the partial water deterioration.The integrated using of the water out of Longhu included the utilization in living, in eco-environment and in agriculture. Based on the water quality evaluation, water quantity estimation and the water using character of the three ways upon, it was built that four combined schemes of the water resource using, and the best way was that Longhu only supply Longzi lake, and the rest water was used in the lower reaches of the river and agriculture irrigation.The calculation results also indicated that it did good to the eco-environment of the riverway and increased the irrigation supply to the down stream farmland through the optimal disposal of the water resource in Longhu, thus decreased the water needed for irrigation from Yellow River of 1.861×10~5m~3/d (6.793×10~7m~3/a), which could prevent the Yellow River of 16 days from water break, according to the smallest flux of 50m~3/s for keeping the runoff.Since there was no such large-scale project of manmade lake system so far, the innovation and the character of the thesis was that the ES value and water resource optimal disposal was done on it. To protect the entering water quality, systemic denitrification and dephosphorization experiments was done to deal with the sanitary water under the technique of aeration biology tank, and received a series of results with important reference value, which offered scientific base to the economical and reasonable optimal circle of the Longhu water system, provided new mind and new methods to this kind of problems later, and had precious reference value for similar project building in future. So there was important meanings for both theoretical study and practical guidance.