Study Of Improved Multi-aggregate Ecological Slope Protection Technique And The Affection On Typical Pollutants In Water Environment

Road runon is consiaerea as one on the main pollution resources on the urban non-point pollutant in China, and contains higher concentrations of organic pollutants and heavy metals, among others. Whereas, part of road runoff only flow through artificial bank before into the urban riverways. For the artificial bank is designed aiming at preventing the loss of water and soil and reinforcing the bank, neglecting the water purification function. That is the reason that riverways and natural water body are polluted by road runoff. In order to improve the water purification function, this research develops an improved multi-aggregate eco-concrete, which strengthens the water purification function, improves the plant affinity, and beautifies the environment with the comparison to the traditional eco-concrete.Dissolved Organic Matter (DOM) is the main components of organic pollutants in road runoff. DOM has complex structure and consists of various reactive function groups, such as carboxyl, carbonyl, hydroxyl, esters, among others. These active function groups react with metal ions (Cu2+, Cd2+, and Pb2+, among others) easily, which affects the morphological structure, distribution, transportation, and bioavailability of metal ions.The improved multi-aggregate eco-concrete is regarded as the medium of the experiment. The water purification function (the removal ratio of COD, TN, TP, and metal ions) was investigated, based on the study of physicochemical characteristics. In addition, the DOM structure variation during the treatment process of improved multi-aggregate eco-concrete was analyzed. Furthermore, the reaction mechanism between DOM and metal ions in different kinds of eco-concretes was studied. The results provide more information of improved multi-aggregate eco-concrete and scientific references for the evaluation the affection of DOM to water environment.Primarily, the optimum ratio of improved multi-aggregate eco-concrete is: volcanic:ceramsite:active carbon:micron-iron is 8:2:2:1, which was obtained from orthogonal experiment. Meanwhile, a four-step pre-packing technology was developed by a serious of stirring-molding experiments based on the traditional eco-concrete forming process, and producing improved multi-aggregate eco-concrete successfully. The void ratio of improved multi-aggregate eco-concrete was 19.7%, compressive strength was 1.9MPa in the 28th day, the weight loss ratio after 20 cycles of freezing and thawing was 3.2%, all physicochemical indexes were close to the traditional eco-concrete that the aggregate diameter is 20-40mm. Furthermore, the plant affinity of different kinds of eco-concretes under the same condition was studied. The resurts showed that improved muiti-aggregate eco-conciete nad remarkadie better plant affinity than other kind of eco-concretes.Secondly, on the aspect of strengthening water purification, different kinds of eco-concretes were applied in this research to study the difference of water purification ability. The results showed that the improved multi-aggregate eco-concrete removal ratio of COD, TN, TP, Cu2+, Cd2+, Zn2+ and Pb2+ was promoted 24.60%,16.91%,26.68%,40.16%,28.75%,23.41%, and 15.60% compared with traditional eco-concrete. Furthermore, the improved multi-aggregate eco-concrete had higher protein- like substances removal ratio than traditional eco-concrete by investigating various spectral technologies.The complexation mechanism between DOM and heavy metal ions (Cu2+ Cd2+ and Pb2+) in the improved multi-aggregate eco-concrete was investigated by Fluorescence Quenching Titration (FQT) and Parallel Factor (PARAFAC). The results indicated that all samples could decompose into three components by PARAFAC successfully, and Cu2+ had stronger binding affinity with protein-like components than others. Cd2+ and Pb2+ had stronger binding affinity with humic-like components than protein-like components. The road runoff samples treated by eco-concrete process were more sensitive to the variation of metal ions than original samples by two-dimensional synchronous spectra. The higher peak region reacted with heavy metal ions primarily by two-dimensional asynchronous spectra. Meanwhile, the ability of DOM complexation sites reacted with heavy metal ions was positive correlation with the reaction sequence by calculating the Log K values.