Research On Mixed Aggregate Planting Concrete Of Nitrogen And Phosphorus Removal

In this study, the single aggregate vegetation concrete was modified. We used the large particle size?size 25 30 mm? zeolite, steel slag and pumice to make porous concrete skeleton, and developed the composited aggregate type of Bahia grass-planting concrete with functions of denitrification and phosphorus removal at the same time. Its denitrification and phosphorus removal efficiency was studied, and the isotope tracer technique was used to explore the denitrification mechanism of vegetation concrete. The main conclusions of this research were:?1? porous concrete material with nitrogen and phosphorus adsorption characteristics was selected through static adsorption test. The results showed that zeolite had a significant adsorption effect on ammonia nitrogen removal while steel slag, pumice on total phosphorus adsorption effect was better than that of zeolite. Through comprehensive evaluation method evaluation, zeolite combine with steel slag according to the quality ratio of 3:1 had obtained a better effect of nitrogen and phosphorus removal.?2? When making vegetation concrete skeleton, a percentage of steel slag, pumice were added to the zeolite, which the vegetative concrete aggregate adsorption of nitrogen and phosphorus was reformed. An experiment was conducted on six groups of composited aggregate planting concrete, in which Paspalum Notatum Flugge? Bahia Grass? was vegetated in pots for 90 days.The impact of composited aggregate zeolite-steel slag and zeolite-pumice on the efficacy of removal of contaminants was investigated. The results showed that the removal rate of NH3-N was from 13.0% to 16.9% after 1 d, approximately 30% of that after 7 d?from 45.7% to 56.7%?. The removal rate of TN was from 9.0% to 14.1% after 1 d, approximately 30% of that after 7 d?from 25.6% to 39.2%?. The removal rate of TP was from 22.0% to 33.3% after 1 d, approximately 40% of that after 7 d?from 57.3% to 89.3%?.The concentrations of NO3--N and NO2--N were low. The concentration of NO3--N was below 0.50 mg/L, and that of NO2--N was below 0.10 mg/L.?3? Aiming at analyzing the contribution of every parts of vegetation concrete system degrading ammonia nitrogen and exploring the nitrogen migration characteristics during denitrification process, ¹⁵NH4 Cl tracer was used and added to six airtight glass containers in this paper. Samples of concrete aggregate, Bahia grass, water and air were acquired on the 1std and 8thd, which were used to determine the 15 N level and analyze 15 N sink. The results showed that the 15 N content increased in plant and concrete aggregate samples, while decreased in water samples, and the 15 N Atom % of air samples had no obvious change. 15 N tracer in each kinds of samples taking up the percent of the initial dosing quantity were respectively, on the 1std: Bahia grass 3.8%⁶.6%, aggregate 11.9%¹7.2%, water 2.9%⁸0.5%, loss 3.3%³.8%; on the 8thd: Bahia grass 65.3%⁶8.7%, aggregate 25.6%²6.2%, water 4.6%⁴.8%, loss 0.8%³.9%. Variance of the 15 N abundance of each kinds of samples indicate that ¹⁵NH4 Cl trace added in the culture solution was mainly absorbed by aggregate at early phase?1d?, while by plant assimilation at later phase?8d?.