The chemical conditioners polymerized ferrous sulfate (PFS), poly(N-isopropyl-acrylamide) (PAM) and a self-made compound flocculant (S003) were used to investigate the dewatering effect on the actual polluted river sediments by simulating actual engineering conditions in the laboratory. The water content of dewatered cakes was 60.22% and 64.77% in the sediment conditioned with PFS and PAM, while the water content was 52.67% with S003. Compared with PFS and PAM, S003 achieved a faster settling rate and removed more turbidity. S003 achieved the best dewaterability of sediments because it had inorganic composition as sediments skeleton and organic compounds with bridging effect, contributing to form large dense flocs with porous structure, which speeded up the sediment settling rate and improved the filtration performance of sediments. In addition, the leaching rates of Cr, Cu, Zn, Ni, Pb and Cd in the solidified products were reduced by 55.8%, 92.1%, 89.2%, 61.4%, 34.2% and 56.3% respectively after conditioning with S003. It demonstrated that S003 greatly improved the sediment dewateribility and had excellent stabilizing effect on heavy metals.

A novel adsorbent of covalently bounded quaternary ammonium activated carbon (CQA) was prepared by silylation reaction with both organosilicon quaternary ammonium salt (QA) and activated carbon (AC) as raw materials. The CQA was characterized by FTIR, SEM and BET. The results showed that QA was successfully loaded on the surface of AC by covalent binding, and had an important influence on the morphology and structure of AC. The nitrate and phosphate adsorption capacities for CQA were greatly improved. The adsorption behaviors of nitrate and phosphate from aqueous solutions on CQA were investigated using batch experiments. The kinetics study revealed that adsorption of nitrate and phosphate onto CQA followed the pseudo-second-order kinetic model, indicating that the adsorption process was mainly controlled by the chemisorptions. The adsorption data fitted Langmuir and Freundlich isotherm models well, and the maximum nitrate and phosphate adsorption capacities for CQA were 14.829 and 8.442 mg/g, respectively. The effects of pH on the adsorption of nitrate and phosphate were also investigated. The results showed that when pH was from 4 to 9, it was suitable for simultaneous removal of nitrate and phosphate from aqueous solution by CQA.