The chemical modification of natural palm fibers with an alkali treatment and the silane coupling agent KH570 were studied to determine the superior mechanical performance and solid engineering application properties of natural fiber/polymer/cement composites. These kinds of natural plant fibers can be easily obtained in China. The characterization of the fibers and composites were performed by Fourier transform infrared spectroscopy, thermogravimetric analysis, mechanical property testing, water absorption testing, and scanning electron microscopy. The results showed that chemical modifications can remove part of the cellulose, hemicellulose, and impurities in the fibers. In addition, the functional groups were confirmed to be grafted onto the fibers, which may cause the fibers to be more compatible with the matrix. Among the fibers studied, the 2 + 5/3% sample (treated first with 2% alkali, then with the 5% silane coupling agent, and subsequently mixed into the system of 3% cement and polymer emulsion) showed a tensile strength of 2.12 MPa, a tensile elongation of 155.114%, and water absorption of 19.65%.

Sulfated denitrification process has attracted more and more attention because it does not depend. on the addition of organic matter. Nowadays, the tailwater from urban wastewater treatment plant has high nitrogen concentration. In this case, we propose a sodium thiosulphate siderite autotrophic denitrifying (STSAD) biofilter for the removal of nitrogen from the tailwater of the urban wastewater treatment plant. Under the optimal conditions, the NO3--N removal rate was 100%, TN removal rate was above 95%. Many microorganisms were enriched on the surface of the ceramsite and siderite filler in the reactor, and the main denitrification microorganisms in the filter were Thiobacillus and Ferritrophicum. The process has certain technical and economic feasibility for denitrification in the tailwater of urban wastewater treatment plant, the cost is only 0.042 CNY/t(water), and the effluent TN and COD meet the requirements of water quality standards, so it is a suitable method.