| Together with oil, steel and coal, natural rubber is also a industrial raw material, is an important strategic material in our country. However, we can't ignore the booming development of rubber industry at the same time causes serious pollution on the ecological environment. In the producing of natural rubber, there will be a large number of waste water and waste water vapor. It's difficult to manage these contaminants, if don't work well, they will cause serious adverse impacts to the peripheral natural environment, hinder the development of natural rubber industry. What's more, natural rubber wastewater is a kind of non-toxic, harmful and resource utilization wastewater. It contains N, P, K, Ca, Mg and protein which are beneficial to plants, but don't have other toxic and harmful substances such as heavy metals (like Hg, Pb). Although studies of the rubber wastewater reusing at home and abroad have been a long time, none had provide specific data to illustrate the soil properties influence from rubber wastewater application.For the rational use of wastewater in the acid coagulant tank and to provide a reference for reasonable utilization and ecological reconstruction of wastewater, the simulation experiment has directly irrigated different concentrations of rubber wastewater in the soil by using soil column perfusion test, exploring the influence on soil.The main conclusion of this study could be briefed as follows:(1) To the soil bulk density. The soil bulk density, which had average increased by1.36%after irrigated stoste wastewater in the acid coagulant tank in the sticky loam. However, it had average reduced by3.19% by diluted for short-term irrigation. It could be showed like this: group of concentration30%<group of concentration10%<group of concentration50%<group of concentration75%<stoste wastewater,4-6times irrigation<1-3times irrigation<7-9times irrigation.Irrigated stoste wastewater in the acid coagulant tank in the sandy loam, the soil bulk density had reduced in short times then increased final by2.9%. After diluted, group of concentration10% and30% primarily had the same variation tendency, both soil bulk density reduced while it increased in middle and high concentration:group of concentration30%≤group of concentration10%<group of concentration50%<group of concentration75%<stoste wastewater,4-6times irrigation<1-3times irrigation<7～9times irrigation.The whole, the soil bulk density of diluted acid coagulant tank wastewater was superior to undiluted wastewater, and the sandy loam had better acid coagulant tank wastewater carrying capacity than the sticky loam.(2) To the soil capillary porosity. The soil capillary porosity was average reduced by12.5% by undiluted wastewater in the acid coagulant tank in the sticky loam. This said that irrigate undiluted wastewater would destroy soil structure and jam soil pore. The contents of sticky loam capillary porosity could be showed:group of concentration30%<group of concentration10%<group of concentration50%<group of concentration75%<stoste wastewater,4-6times irrigation≤1-3times irrigation<7-9times irrigation.In the sandy loam, the capillary porosity had not variate largely (vary within2%), but also would harden soil after longtime rubber wastewater irrigating. The experiment showed that: group of concentration30%<group of concentration75%≤stoste wastewater<group of concentration10%<group of concentration50%,4-6times irrigation≤7-9times irrigation <1～3times irrigation.The whole, the soil capillary porosity influenced by diluted acid coagulant tank wastewater was superior to undiluted wastewater, and the sandy loam had better acid coagulant tank wastewater carrying capacity than the sticky loam.(3) To the soil hydrophily. The capillary water holding capacity was average reduced by15% in the sticky loam irrigated by undiluted wastewater. In the experiment, not the concentrations but the times relatively affected more on soil hydrophily, led to appear obvious repellency:4-6times irrigation≥1～3times irrigation>7～9times irrigation.In the sandy loam, the capillary water holding capacity had not variate largely (vary within2%), and the maximum water holding capacity also had not reduced obviously. It indicated that irrigated rubber wastewater had not caused obvious repellency in the sandy loam:group of concentration30%> group of concentration75%≥stoste wastewater> group of concentration10%> group of concentration50%,4～6times irrigation≥7-9times irrigation>1～3times irrigation.Synthesize (2) and (3), we could analyze that wastewater concentration is too low to have enough organic and inorganic polymer to glue sandy loam particles, or lead to soil regulation performance reduced. So, by reducing wastewater concentration blindly not always lead to lower influence on sandy loam property. Sandy loam property could only be improved effectively by irrigating rubber wastewater of appropriate concentration. Thus, to reduce the pollution of rubber wastewater from the source, we can treat rubber wastewater of appropriate concentration as sandy loam conditioner, or make it into the liquid fertilizer for utilization.(4) To the soil waterstable aggregate. Different concentrations of wastewater in the acid coagulant tank in the sticky loam increased by32.21%-237.97% apiece, the ascensional range was130%. The reason should be that organic polymer in wastewater formed membrana reticulata surfaced the soil particle to avoid the soil fine particle disperse from the aggregates. The contents of soil waterstable aggregate could be showed like:group of concentration10%< group of concentration30%<group of concentration50%<group of concentration75%<stoste wastewater,1～3times irrigation<4-6times irrigation=7～9times irrigation.In the sandy loam, different concentrations of wastewater in the acid coagulant tank increased by47.4%～114.1% apiece. Among them, the group of concentration10% was the lowest while the group of stoste wastewater was the highest. The contents of soil waterstable aggregate could be showed that:group of concentration10%<group of concentration30%<group of concentration75%<group of concentration50%<stoste wastewater,1-3times irrigation≤7～9times irrigation<4～6times irrigation.The whole, with the growth of wastewater concentration, the contents of soil waterstable aggregate increased. It indicated that more organic polymer better soil particles cemented. However, the waterstable aggregates had no significant changes in the later test, which showed that the soil had reach the bearing cap from the wastewater in the acid coagulant tank.(5) From the test of water disintegration in soil, we can see that lots of organic polymer would cement the soil particles then sink together reaction occurred irrigated by undiluted for a longtime. Sandy loam column consolidate effectively and had not apart in72hours in water, this consists with the data irrigating with undiluted wastewater. Consideration on futher study of the acid test of wastewater tank sandy loam soil and water conservation ability, for acid trough of recycle of waste water directly looking for new ideas. To look for new ideas on direct utilization of wastewater in the acid coagulant tank, further study of irrigating wastewater in sandy soil on its soil and water conservation in later tests could be considered. |
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