Study Of In-situ Remediation Of Heavily Polluted Water By Combined Ecological Enhancement Technique

The study based on the summary of a large number of related research results,aiming at the characteristics of pollution degree of artificial ponds,the purification effect of in-situ restoration of polluted static water body by combined ecological enhancement technology was studied.The following conclusions are drawn from the laboratory pilot and pilot engineering tests:（1）The ecological floating islands formed by the combination of yellow-flower-fleur-de-lis and improved volcanic rocks have a good removal effect on pollutants in the water body.Even some indexes are reduced to the V class standard of surface water.The removal efficiencies of chemical oxygen demand(COD_Cr),ammonia nitrogen（NH₄⁺-N）,total nitrogen（TN）and total phosphorus（TP）were 62.95%,67.45%,51.99%and 77.78%respectively.In the experiment,it was found that the orris-de-lis had a good synergistic function with the improved volcanic stone and the microorganisms growing in it,so as to remove the pollutants in the water.Summarized from the trials for different water pollution situation,reasonable collocation for combination of the afi can realize the rapid degradation of pollutants and the purpose of purifying water quality.At the same time,it just needs low investment and has good environmental ecological benefit.It also can have certain landscape effect.It’s very suitable for urban water especially residential area in the static water beautification governance.（2）The ecological management structure was further strengthened by planting submerged plants in the water.The test results showed that the collocation of selected four types submerged plants and the ecological floating island combination system had a better effect on relatively heavy polluted water purification compared with a single floating island system purification effect.Waterweed showed the best adaptive optimal in the four types submerged plant.The group of COD_Cr,NH₄⁺-N,TN and TP removal rate were 79.01%,85.91%,84.82%and 78.72%respectively.Although the nitrogen removal rate of the local pondweed system was relatively high,it was not suitable for the pilot test because of its fiercer growth and frequent decline in the later period of the experiment.Due to the short test period,the late growth status of other submerged plants was not discovered.In order to prevent the growth of floating island plants from reducing the lighting of submerged plants,it is necessary to properly match the planting methods and proportions of floating island and submerged plants.Several suitable submerged plants with both economic and environmental benefits were selected for the pilot project.（3）An engineering restoration test was conducted on an artificial pond by combining dredging of sediment,microbial preparation and ecological enhancement technology.The total area of the experimental water area was 3200m²,and the average water depth was 1.3m.The results showed that both the floating island plants and the submerged plants grew well after 3 months of restoration.Water quality was tracked and tested every week,and the results showed that the average values of conventional indexes in water,such as chemical oxygen demand(COD_Cr),ammonia nitrogen（NH₄⁺-N）,total nitrogen（TN）and total phosphorus（TP）,decreased by 83.28%,92.26%,92.42%and85%,respectively,compared with the initial stage of the experiment.During the test,quotas of COD_Cr,NH₄⁺-N,TN,TP were significantly lower than the control area,water transparency（SD）was maintained at an average of 1.5m,and the overall water quality reached the national surface water quality standard III.The successful implementation of this restoration project provides technical support for the subsequent overall restoration and other ecological restoration projects.