Advanced Materials Research Vols. 610-613

Abstract: The paper introduced the source and harmfulness of heavy metal pollution in water environment and summarized the applications of the chemical method, physiochemical method and biological method in heavy metal pollution of sudden emergency accident. Meanwhile, the heavy metal pollution emergency processing technology of rivers, lakes and other water bodies were elaborated and the emergency engineering technology of heavy metal pollution in rivers and lakes were analyzed. Finally, the application of bioremediation on heavy metal pollution caused by sudden emergency accident was prospected.

Abstract: Polymer heavy metal chelating agent containing hydroxamic acid groups (PHA) was made in order to observe its effects on the removal rate of Cd²⁺. The present study reaches the following results: (1) On conditions that pH value is 8.0, the chelating agent is 60mg•L^-1 and the reaction time is 60min, the highest chelating capacity of the polymer heavy metal chelating agent PHA can reach 341 mg/g. (2) The existence of common cations: K⁺, Na⁺and Mg²⁺ can improve PHA’s ability to remove Cd²⁺. (3) The existence of common anions Cl^-, SO₄^2- and NO₃^- can improve PHA’s ability to remove Cd²⁺. (4) Co-existing with the turbidity-causing materials, PHA’s removal abilities of Cd²⁺ and turbidity are mutually promotive. (5) The chelating product, Cd-PHA’s amount of leaching of Cd²⁺ is only 1/11 of that in neutralization titration ,having a relatively higher stability and better environmental safety.

Abstract: Treatment of actual domestic wastewater at ambient temperature, even low temperature is considered to be difficult by traditional systems. The present study is related to treatment of actual domestic wastewater in an EGSB reactor. The study showed the effectiveness of biological treatment of actual domestic wastewater involving appropriate microorganism and granules in an EGSB reactor. At 26°C, the reactor was operated at 18.7kg COD.m−3.d−1 of average organic loading and 83% high COD removal efficiency, and even at the highest loading rate of 57.12kgCOD.m−3.d−1, the COD removal efficiency still could attain to 68%. Varied influent flow need to supply varied optimal and thus to ensure the optimal removal effect. Low temperature would cause pollutant removal rate decrease. However, enhancing could optimize the contact of sludge and wastewater and thus strengthen the performance effect. Modified Stover–Kincannon model was applied to data obtained from experimental studies in EGSB reactor. Treatment efficiencies of the reactor were investigated at different hydraulic retention times (0.5-1.3h) and different operation temperature (15°C, 26°C). The modified Stover–Kincannon model was best fitted to the EGSB reactor, and the substrate utilization rate( ), saturation constant value( ), and actual pollutant removal rate( ) were found to be , , and for 26°C, , , and for 15°C( before increasing ), and , , and for 15°C(after increasing ). Low temperature could cause decrease and thus cause distinct decreasing of COD removal efficiency. However, increasing could increase and accordingly increase COD removal efficiency.

Abstract: The biological phosphorus (P) removal characteristics of a full-scale Unitank wastewater treatment plant (WWTP) were investigated by field survey, model analysis and sludge P content determination. In the Unitank WWTP, oxidation-reduction potential (ORP) reached the lowest value of -17 mV and the highest value of 130 mV at the end of anoxic/anaerobic stage and aerobic stage, respectively. The anaerobic P release process could be fitted by first-order kinetics with rate constant of 3.52 h^-1, while the maximum aerobic P uptake rate was 3.31 mgP/(L•h). The measured sludge P content in the Shidongkou WWTP was 15.4±2.1 mgP/gSS, significantly lower than that in full-scale AAO WWTPs.

Abstract: The adsorption behaviors of chlortetracycline on two kinds of granular activated carbons with different BET surface area and average pore width have been studied. The results show that larger BET surface area is beneficial for the adsorption capacity, and wider pore structure can enhance the adsorption rate. Initial solution pH has great effect on the adsorption behavior, and the suitable pH for the effective adsorption is from 4 to 8.

Abstract: Determination of parameters is an important work for establishing the water quality model to perform the mathematical simulation. In this paper, the improved genetic algorithm is applied in evaluation of the parameters of S-P water quality model. This method has overcome the shortages of parameters estimation as before. The computed results have indicated this method with a very high precision and easy realized by the computer.

Abstract: The activated carbon fiber(ACF) electrodes were prepared for electrosorption desalination. The electrodes were analyzed using scanning electron microscope (SEM), and the desalting efficiency was represented by the removal rate of Cl-. As a result, desalting efficiency decreases with increasing initial concentration of Cl-, whereas the total adsorption capacity increases. The most suitable voltage for electrosorption desalination is 1.2 ~ 1.4V. The electrosorption desalination achieves the best results while the distance between two electrodes is 1.0cm. Electrosorption plays a more important role in the adsorption process compared with physical adsorption. The removal rate of Cl- is obviously improved by using ACF electrode modified by HNO3 and KOH and desalination ratio of the electrode treated with KOH is increased by 16.5%. Therefore, the ACF electrode would be suitable for using in the application of electrosorption desalination.

Abstract: Selected six soil profiles in a relocation paint factory, respectively sampling at 20cm, 50cm, 100cm of each profile and detecting the Pb、Zn、Cd、Ni content to research the vertical distribution and pollution characteristics. The results showed that: part of the sample profiles were in different degrees of pollution by Pb and Zn. When the heavy metals were not accumulated in the soil upper layers, the content of the heavy metals fluctuated around the background value, when the heavy metals were accumulated in the soil upper layers, the heavy metals contents down a decreasing trend from upper layers to lower layers.

Abstract: The occurrence and removal of polycyclic aromatic hydrocarbons (PAHs) was examined at different stages at a anaerobic-anoxic-oxic biological wastewater treatment plant in Qingdao City, eastern China. Results shown that 13 PAHs were detected at different treatment stage in wastewater and sludge. The total concentration in the influents was 15194.3ng/L, higher than the existing reports. Most abundant PAHs in influent were Naphthalene, Benzo(g,h,i)perylene, and Pyrene, accounting for 86.4%. The removal efficiencies of individual PAH compounds ranged from -7.5% to 73.5% in the total treatment process. A significant relationship was observed between the removal efficiency and log Kow of the PAH compounds in the grit stage (when the values of log Kow were higher than approximately 5), suggesting that these compounds were principally removed through sorption to sludge particles and transfer to sludge processing systems. In secondary stage, the removal efficiency of PAHs was only 4.4% due to impact of low temperature on biological activity. The removal efficiency of 28.8% indicated A2O process was not ideal in removing PAHs.

Abstract: The lignin removal of pulping process is left in black liquor, and with relation to the paper pulp lignin. The higher the black liquor lignin content is, the bigger the lignin of paper pulp is removed. This paper analyzes the delignification mechanism of wheat straw atmospheric pressure pulping with microwave radiation. The relations of black liquor lignin content and alkali concentration to pulping time are described in detail. The results show that delignification process is divided into two stages: quick stage and residual stage. The lignin removal rate in the first stage is much higher than the second stage, that is, lignin has been removed more sufficiently after quick stage. In first stage, reaction order of delignification is 1.0, and 0.7 with respect to OH-, the activation energy is 38.62 kJ • mol^-1. The latter delignification also belongs to the first-order reaction and 4.4 with respect to OH-, the activation energy is 75.56 kJ • mol^-1. Apparently, residual stage needs to consume large amounts of energy to removal lignin.