| A small-scale subsurface-flow constructed wetland(SFCW) for treating processed natural rubber wastewater(PNRW) has been studied in the investigation. Based on these methods of outdoor model experiment, routine sampling, and laboratory chemical analysis etc., the basic characters and treatment situation of PNRW were investigated systematically; the technical parameters of the system was optimized; the plantation and the nutrient components of the wetland reed was compared with those of control; and the influence of soil and environment by SFCW were also analyzed in the paper. The chief results are showed as follows:(1) Most of PNRW in Hainan can't meet Ths National Discharge Standard, and PNRW leads to secondary pollution to environment during the rubber process and when discharged into receiving water. The useful substance of PNRW is hardly utilized resulting in the waste of resource.(2)the purifying effect of the wetland system for treating PNRP The SFCW system treating PNRW had obvious purifying effect, and the removal ratios of the chief pollutions of CODcr BOD5 and NH3-N were high. Under the conditions of hydraulic loading(HL) being 0.017 m3-(m2d)-1, hydraulic retention time(HRT) being 3 days, the average removal ratios of CODcr, BOD5, NH3-N of washing wastewater were 92.24%, 95.49%, 68.67%, respectively; under the conditions of HL being 0.016 m3(m2d)-1, HRT 3 days, the average removal rations of CODcr, BOD5, NH3-N of synthetic wastewater were 91.07%,93.07%,75.55%, respectively. This treatment technology was effective with stable effluent quality and good resistance to shock-loading.(2)The purifying effect was influenced by HL, HRT and pollution loading(PL). Under the experiment conditions, the optimum combined parameters of the washing water were that HRT was 3d, HL was 0.017 m3 md), CODCr loading was 32.86 g (md) and NH3-N loading was 2.87 g(md); the optimum combined parameters of synthetic wastewater were that HRT was 3d, HL was 0.016 mmd), CODCr loading was 23.94 g(m d)-1 and NH3-N loading was 4.92 g(m d)-1. Except for NH3-N, the other indexes of above two types wastewater can meet the standard of the Wastewater Synthetic Discharge (GB8979-1996) stipulated by government.(3)NH3-N was one of the limiting factors in this experiment using SFCW system. The purifying effect of NH3-N was obvious and better than that in Hainan, but the attainment to discharge requirement of effluent was difficult because the influent concentrations was too high. So the purifying capacity of the previous treatment and the SFCW system should be strengthened.(3)The growth condition and the nutrient components of the wetland reed were compared with that of control. The study suggested that the wetland reed growed better than the control, and the wetland reed contained more coarse protein and coarse fibre than those of the control, but amount of coarse ash of wetland reed and the control was almost identified. These results indicate PNRW containing the nutrient substances is helpful to plant growth and can improve the reed quality and output.(4)In the view of the soil characters, that the concentrations of soil organic matter, total nitrogen(TN), total phosphorus(TP) reduced when the wetland system was carried out with a span It showed that the treatment for PNRW may reduce the nitrogen of wetland soil and fasten the soil organic matter degradation. So carbon resource such as treacle waste should be supplied to improve the purifying effect of wetland transaction system and reduce the influence of soil characters caused by the wetland system.As a whole, SFCW being a whole ecological system, with a internal good circulation achieved the goal of wastewater transaction and resource utilization, andhad a considerable ecological value. The wetland provided a low-cost, easily-managed system that had a obvious purifying effect for PNRW and a high level of NHj-N removal ratios. It also had a satisfactory environmental and ecological value. So SFCW is a PNRW treatment method deserving further investigation and application.
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