Yong Sheng Zhao

Effect of illumination on the hydrogen-production capability of anaerobic activated sludge

To investigate the influence of illumination on the fermentative hydrogen production system, the hydrogen production efficiencies of two kinds of anaerobic activated sludge (floc and granule) from an anaerobic baffled reactor were detected under visible light, dark and light-dark, respectively. The 10 mL floc sludge or granular sludge was respectively inoculated to 100 mL diluted molasses (chemical oxygen demand of 8000 mg·L−1) in a 250 mL serum bottle, and cultured for 24 h at 37°C under different illumination conditions. The results showed that the floc was more sensitive to illumination than the granule. A hydrogen yield of 19.8 mL was obtained in the dark with a specific hydrogen production rate of 3.52 mol·kg−1MLVSS·d−1 (floc), which was the highest among the three illumination conditions. Under dark condition, the hydrogen yield of floc sludge reached the highest with the specific hydrogen production rate of 3.52 mol·kg−1MLVSS·d−1, and under light-dark, light, the specific hydrogen production rate was 3.11 and 2.21 mol·kg−1MLVSS·d−1, respectively. The results demonstrated that the illumination may affect the dehydrogenase activity of sludge as well as the activity of hydrogen-producing acetogens and then impact hydrogen production capacity.

Natural Attenuation of Diesel Pollution in Sand Layer of Vadose Zone

The natural attenuation process was studied by vadose zone simulating indoor to quantify the adsorption, biodegradation and volatilization of diesel oil. Through adsorption experiment, adsorption equilibrium time of diesel sewage by fine sand was 24 h, and maximum theoretical adsorbance to Total Petroleum Hydrocarbon (TPH) was calculated to 234 mg/kg. Through the contrasts of three columns, the first-order attenuation kinetics equations of biodegradation and volatilization in the diesel polluted sand layer of vadose zone and the half-life time were established. According to the experiments, absorption, biodegradation and volatilization all played important roles, they were very major roles in natural attenuation.

Survey of Combined Hydrogen-Methane Production in Anaerobic Baffled Reactor (ABR)

Anaerobic fermentative technology is an important route to solving environmental pollution and resources problems. Combined hydrogen and methane production in a two-stage process is a concept which has been developed in recent years Anaerobic biological treatment organic wastewater can produce large amounts of hydrogen and methane，which can be used as energy carrier. At present，the research focusing on the adjustment of fermentation hydrogen-methane production has been conducted. Furthermore, the simultaneous hydrogen-methane production was tested and optimized. However, it lacked combined hydrogen-methane production in an anaerobic reactor in literature so far. Based on preview experiment, the paper studied the simultaneous hydrogen-methane fermentation in an anaerobic baffled reactor (ABR) system. ABR has the advantage of biomass phase separation and integration of acidogenic and methanogenic processes to simultaneously conduct hydrogen-methane production during wastewater treatment. Through deep biohydrogen production, it can enhance the activity of hydrogen-producing acetogens (HPA) and the efficiencies of the combined hydrogen-methane fermentation system. It showed to enhance the activity of HPA was the key to the combined hydrogen-methane production.

Study on Influencing Factors on Removal of Diesel Oil from Unsaturated Zone by Soil Vapor Extraction

This paper deals with the influencing factors on removal of diesel oil from by soil vapor extraction (SVE) method. A series of one-dimensional column experiments were conducted to study the influencing factors for SVE method, the factors included extracted vapor flow rate,water content and the concentration of the contaminant. The results indicated that: (1) the increase of vapor flow rate led to higher contaminant removal efficiency,but the increment of removal was not significant at higher flow rate levels;(2) the moisture content is 12% coarse sand elimination rate is bigger than 1% coarse sand;(3) the soil index of oil is higher, the extraction time to be longer, it is not suitable processes with SVE that the diesel oil density is excessively low.

Study on Degradation of Nitrobenzene in Groundwater by Fenton-Like Oxidation Based on Iron in Aquifer Materials

Fenton and Fenton-like reactions are regarded as high efficient methods in advanced treatment of nitrobenzene wastewater but both restrained in degradation of nitrobenzene in groundwater because of the low pH condition( less than 4 ) requirement and other problems such as secondary pollution by the irons in contaminated sites. This paper reports a new Fenton-like technology combined irons extraction from aquifer materials which were found in a nitrobenzene contaminated site in China with hydrogen peroxide catalytic oxidation. The simulate experiments were conducted to investigate the oxidation of nitrobenzene in groundwater by this method under the condition of neutral pH and 8~10°C. The comparison of different extraction agent and production rule of hydroxyl radical were both studied in this research. The results indicated that extraction had hysteresis property because the highest extracting efficiency occurred after 36h. Extraction agent DCB has the highest efficiency, for Fe3+ was 62.92% and Fe2+ was 30.17%. The highest removal efficiency could reach 80.2% while the mole ratio of nitrobenzene to H2O2 was 1:200. Three stages could found in hydroxyl radical generation process, in the first stage hydroxyl radical generated rapidly in 0~30min, then decreased slowly between 30min and 120min, at last the generation tended to be steady after 120h. The results could possess a good potential for application in the treatment of nitrobenzene contaminated groundwater and provide theoretical basis on in-situ chemical remediation technology of nitrobenzene contaminated sites.

Influence of Fly Ash on Clay Liner

Compacted clay is commonly used as an essential material for reducing the permeability in landfill sites. However, compacted clay has defect with shrinkage and desiccation cracking during cyclic drying and wetting, which may increase hydraulic conductivity of compacted clay. It’s necessary to modify clay, and make it have anti-cracking performance. The main objective of the study is to determine the content of fly ash on clay. Laboratory tests were done to determine optimum moisture content, hydraulic conductivity, volume shrinkage on different content fly ash modified clay. It was determined that a certain proportion of fly ash can improve the permeability of clay, and reduce the cracking clay.

Influence on velocity of groundwater flow in nitrobenzene degradation by fenton-like oxidation based on natural iron extraction

The catalytic efficiency of iron (II, III) extracted from aquifer materials by DCB(dithionite-citrate-bicarbonate) to promote Fenton-like reaction and the influences of groundwater velocity upon the oxidation efficiency of catalytic reaction were both examined by employing Nitrobenzene (NB) as a model compound at neutral pH (8~10°C). Fine sand, as the solid catalyst, was selected and simpled as the most-represented aquifer materials in a famous nitrobenzene contaminated site of China based on hydrological analysis. The results indicated that the adsorption to the catalyst changed significantly with the pH value and the sorption isotherm was fitted using the Langmuir model, agent DCB performed the best but also has hysteresis property. The highest removal efficiency could reach 80.2% while the mole ratio of nitrobenzene to H2O2 was 1:200. On the basis of the findings, one-dimensiona soil column experiments further indicated that groundwater flow velocity could strongly impact the occurrence of extraction agents and aquifer materials so that the effective degradation of NB were repressed due to the lack of extraction reaction time or scavenging effect of hydroxyl radical by H2O2.

Study on Transformation Rules of Diesel Fuels Contaminated Aquifer

Study on migration and transformation rules of diesel fuels pollution by using two-dimensional plexiglass tank to simulate underground aquifers. Through regular monitoring of the sampling ports in total petroleum hydrocarbon content of the water to determine the diesel fuels in the medium sand aquifer in the migration process, and compute out parameters of diesel fuels pollution in the medium sand aquifer in the mathematical model of migration. This prediction of diesel fuels pollution in the migration of sand media. The results showed: the highest values of different sampling ports used by the time its location is closely related to distance to sources, the concentration rose to the highest value used in a short time. The sampling ports far away from the pollution spilling place rose to the highest value of concentration used in a long time. After diesel fuels leaked 40 d later, the simulation of pollutants reached the bottom slot, and diesel fuels can be calculated transfered with a speed of 1cm•d-1, and then after 20 d more, TPH can be moved to simulate the water tank side pollution of the aquifer region.

Research on Natural Attenuation of BTEX and Changes of Redox Environment in the Process

Natural attenuation of BTEX and characteristics of the water in the study are researched in this paper. The study not only obtain the attenuation rules of BTEX over time, but also the rules of the redox materials of the contaminated groundwater over time. From the study, we reach conclusion that the redox conditions is changed with the increasing pollution of BTEX and the oxidation condition changes into reducing condition. With the changing of the redox condition, there take place a variety of redox reactions. The materials of oxidation, such as O2, NO3-, Fe3+and SO42-, are transformed into reduction materials, such as NO2-, Fe2+, S2- and so on. In this process, the components of BTEX are degradated by micro-organisms which using the oxidation materials as electron acceptors.

Natural Attenuation of Diesel Fuels Contaminated Medium Sand with Different Water Content in Vadose Zone

Comparative experiment of 3 medium sand columns was executed to research the influence of water content on natural attenuation of diesel fuels contaminated vadose zone. The results showed that: The lower the water content, the stronger capacity of retarding diesel fuels was. After a diesel fuels spill, the average concentration of TPH were 57.7 g•kg-1, 47.55 g•kg-1 and 31.95 g•kg-1 in medium sand with different water content (0.66 %, 8.00 % and 15.22 %). Besides, the TPH found 90 days after the natural attenuation degradated by 38 % and 44.62 % 4 of the initial contaminant load of the medium sand with water content 0.66 % and 8.00 %. Additionally, the higher the water content, the larger the microbial activity of sand was. Biodegradation was the important mechanism for natural attenuation of diesel fuels.