Advanced Materials Research Vols. 726-731

Abstract: The heavy metals (Pb, Zn, Cu, Cd, Cr) and metalloid (As) in surface sediments and water samples from un-dredged and dredged areas in Dianchi Lake had been analyzed to investigate the removal efficiency of sediment dredging. Potential ecological risk index (RI) and simplified geoaccumulation risk index (Igeo) were used to assess the heavy metals accumulation and ecological risks. The results indicated that Pb²⁺, Zn²⁺, Cu²⁺, Cd²⁺, Cr²⁺ and As³⁺ were not detected in water of Dianchi Lake, and the heavy metal content of surface sediments in Caohai Lake was in the order of Zn²⁺>Pb²⁺>Cu²⁺>As³⁺>Cr²⁺>Cd²⁺, and that in Waihai Lake was in the order of Zn²⁺>Pb²⁺>Cu²⁺>Cr²⁺>As³⁺>Cd²⁺. Through comparing the heavy metal content in sediments from un-dredged and dredged areas, pollutants reduced after sediment dredging, which can be reflected by the Igeo values too. Potential ecological risk index showed that the potential ecological risks were at low level in Dianchi Lake after sediment dredging.

Abstract: Using manganese ore coated with small stones to adsorb arsenic from the contaminated water samples of Yangzonghai Lake, and several factors that may have impacts on the arsenic removal efficiency are analyzed. The result shows that the new adsorbent material has a great effect on arsenic removal. Temperature's effect on arsenic removal efficiency is not obvious. The arsenic removal efficiency increased dramatically in accordance with residence time within 0-660s, and then stabilized. The adsorption process is better when conducted in acidic conditions, the maximum adsorption rate reached 83.0% with the pH of 3.0 and it reached the minimum value of 14.7% when pH is 10. Fe³⁺ and Ca²⁺ can slightly promote manganese ore's adsorption of arsenic, and with anions CO₃^2-, SiO₃^2- , efficiency was slightly reduced. When fitting the kinetics data of arsenic removal by coated manganese ore, the adsorption process is correspondent with first-order reaction kinetics model. The adsorption isotherm is more close to the Freundlich isotherm model.

Abstract: This passage takes the four local common aquatic plants as research objects to do research on the removal rate of TNNH₃-NTPPO₄^3-BOD₅COD_Cr from static landscape water. It gets the following results: vetiveria zizanioids does best in removal of nutrient; pistia stratiotes does best in removal of BOD and COD_Cr, which can provide theoretical basis for landscape water aquatic repair.

Abstract: The adsorption kinetics and influencing factors deduction showed that adsorption process accorded with a second-order kinetic equation according to academic hypothesis. The result was validated by the phosphate adsorption onto Veria-Based adsorbent. The factor (m/V) ^b had the close relation with the adsorption speed and the adsorbent dosage, intensity exponent b=0.44 (0b1) in this test condition. All the results show that phosphate adsorption on the adsorbent surface was mono-layer chemisorptions and that the hypothesis of kinetic inference was reasonable.

Abstract: This work focused on the advanced treatment of the secondary treated ethylene chemical plant effluent, which contained high conductivity and high organic concentration. To reduce the cost and improve operation stability, a biological aerated filter-ultrafiltration-reverse osmosis (BAF-UF-RO) process was proposed. The feasibility and effectiveness of the BAF loaded with a novel non-sintered fly-ash ceramsite (NSFC) as pretreatment method were investigated in detail. The results showed that the COD, turbidity, NH₃-N and SDI₁₅ in the effluent from the BAF were reduced largely. The BAF-UF-RO process was stable with the recovery rate of 75%, and the desalination rate was up to about 97.5%. Moreover, the operating pressure and backwash frequency of RO maintained 0.94-0.98 MPa and 2 times/d, respectively. After continuous operation for four months, there appeared to be no need for chemical cleaning of the RO membrane.

Abstract: Ammonium nitrogen pollution is a key factor related to water eutrophication. In our works, biochar adsorption for ammonium nitrogen removal from wastewater has been investigated. Transmission Electron Microscope with energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier Transform Infrared spectroscopy was performed to characterize the prepared biochar. The optimal solution pH, and coexisting ions effect for ammonium nitrogen removal from wastewater was examined. Surface characterization demonstrated the obtained biochar was coarse, unshaped, irregular, and contained a great deal of carbon. With an increase in solution pH, biochar adsorption amount of ammonium nitrogen was decrease. With an increase in coexisting ions concentration, biochar adsorption amount of ammonium nitrogen was decrease.

Abstract: To study the hyporhic zone of Shifosi reservoir in the conversion process between the three main pollutants nitrogen, this paper applied HYDRUS-1D software to simulate 200cm of soil profile depth in 200 hours mutual transformation behaviors. Results show that interact in complex environment and microbial flora, under the action of the 105cm of ammonium nitrogen and nitrite-nitrogen fully translated into nitrate-nitrogen, 200cm nitrate-nitrogen denitrification process almost completely converted into nitrogen gas.

Abstract: The structure and surface chemical properties of activated carbon after nitric acid modification and their influences on adsorption and catalytic ozonation of acid red 3R were investigated. The results showed that both specific surface area and micropore volume of activated carbon decreased, but mesopore volume increased after nitric acid modification. The adsorption capacity and catalytic ozonation performance of modified activated carbon were influenced due to the increased surface acidic functional groups. The adsorption capacity of modified activated carbon was enhanced under acidic condition due to dispersion interaction between increased surface acidic functional groups and acid red 3R. The increase in surface acidic functional groups of activated carbon was also considered to be responsible for improvement of the catalytic ozonation of acid red 3R under alkaline condition, because of their participation in the ozone decomposition and OH generation.

Abstract: The black soil was taken as the research object, and the phosphorus sorption-desorption kinetics characteristics of different components of colloidal dispersion complex in black soil were studied. Results showed that the maximum phosphorus adsorption amount by different components of the colloidal dispersion complex decreased in the order of G₀ < G₁2, and the adsorption amount would be stable as the time increase, while the desorption amount was in the order of G₁>G₀>G₂. The Elovich equation was the optimal model to describe phosphorus adsorption by different components of colloidal dispersion complex, which fitted better than the Two-constant equation.

Abstract: The influence of aeration intensity on membrane fouling in an integrated non-woven membrane bioreactors (MBR) was investigated. MBR with aeration intensity of 0.1 and 0.2m³/h was operated for artificial wastewater for 30 days. The effect of aeration intensity on quantity of extra-cellular polymeric substances (EPS), soluble EPS (EPS_S), bound EPS (EPS_B) and SUV₂₅₄ in suspension of MBR were also investigated. The results show that high aeration intensity can improve membrane fouling in certain scope. With increasing of aeration intensity, the quantity of EPS, EPS_S EPS_B and SUV₂₅₄ in suspension increase and irreversible fouling resistance also increases.