Applied Mechanics and Materials Vols. 253-255

Abstract: An ultrafiltration (UF) unit was used for tertiary wastewater treatment at a wastewater plant. The pilot study showed that UF is effective to remove turbidity, total bacteria and coliform bacteria from the secondary effluent to obtain high quality filtrate for water reuse, but UF is not very effective in the removal of dissolved substances such as colour, UV₂₅₄ and TOC, and the removal efficiency and permeate flux can be improved by conducting PAC adsorption or coagulation prior to UF operation. The backwash is essential to obtain a higher permeate flux.

Abstract: Gas emission dynamic prediction is a non-contact and continuous outburst prediction method. It is based on the difference of gas emission characteristics whether the working face exists dangerous factors, selecting appropriate indicators to predict outburst danger. The indicators that reflect abnormal gas emission is divided into four types: gas content, desorption characteristics, gas emission fluctuation and gas emission trend change. This paper gives the calculation model of A index that reflect desorption gas content, B index that reflect coal structure and desorption gas characteristics, S index of gas emission standard deviation, Kv index of gas emission variation coefficient. The validity of the real-time prediction using gas emission index for the working face outburst danger is verified by typical cases.

Abstract: PAN microspheres were crosslinked with divinyl benzene (DVB) and styrene (St), and then pre-oxidized under atmospheric pressure, porous carbon microspheres were produced by carbonizing the pretreated microspheres under nitrogen protection. Morphology and structure characterizations of the materials were performed by employing scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption test, etc. The results show that the primitive PAN microspheres display flower-like structures, while the carbonized pretreated PAN microspheres exhibit a high porosity as well as specific surface area and have a good adsorption of methylene blue (MeB) dye.

Abstract: In order to explore methods of improving phosphorous and nitrogen removal in sludge reduction technologies, an advanced process combining sludge reduction and phosphorous and nitrogen removal was developed, for short, HA-A/A-MCO Process (Hydrolysis-Acidogenosis -Anaerobic/Anoxic-Multistep Continuous Oxic tank). Under the condition of this process achieving favorable effect of phosphorous and nitrogen removal and sludge reduction, test results of the process treating campus wastewater showed that when influent COD was 316-407mg/L, effluent COD was lower than 18mg/L, and COD removal rate exceeded 96%. When return ratio of anaerobic P-release sludge entering into hydrolysis-acidification tank was about 2% of influent flow, most anaerobic P-release sludge was translated into organic matter and it mainly contained VFA(about 275mg/L), which was 4.74 times as much as that(58mg/L) in original sewage. Supernatant which was rich in VFA from hydrolysis-acidification tank entered into subsequent A2/O cells, which could provide affluent carbon source for phosphorous and nitrogen removal.

Abstract: The removal of organic pollution humic acid from aqueous solution by inorganic flocculent poly aluminium chloride (PAC) was investigated. Flocculent was dosed under medium stirring speed of 250 r/min for 2 min, and then changed to the speed of 45 r/min for 12 minutes. And the single influential factor such as: the dosage of the flocculent, the settling time, the pH value, the initial concentration of the humic acid solution and the initial tempreture of the humic acid solution were investigated. When the initial concentration was 10.0mg/L, the pH value was 6.5 and the dosage of PAC was 28.0 mg/L, the removal rate could reach the maximum 74.2%.

Abstract: In this paper anaerobic digestion of dairy manure and straw was conducted to produce biogas. Under the conditions of C/N=25-30 and T=36°C, five kinds of dry matter concentration of 20%, 15%, 10%, 5% and 2.5% were tested to investigate the effect of dry matter concentration on anaerobic digestion. The result showed that first 30 days was the biogas production peak phase and VFA concentrations in the leachate were also high during the same period. When dry matter concentration increased, biogas production appeared larger fluctuation, and alkalinity and NH4+-N concentration in the leachate also increased with higher organic loading rate. Among five kinds of dry matter concentration, 10% was more suitable for anaerobic digestion to produce biogas with total biogas production amount of 4710 mL after 30 days and volumetric biogas yield of 0.313 m3•m-3•d-1. These results could provide instructive meaning to the engineering application of dry anaerobic digestion.

Abstract: In this report, a strains of nitrifying bacteria HFX08 with low temperature and low carbon nitrogen ratio is separated from the activated sludge which is domesticated of the northern city sewage plant in winter. The optimum carbon source for the growth of the strain is sodium acetate, the source of nitrogen is potassium nitrate and the optimum growth temperature range is 10-20°C correspondingly.

Abstract: Harmful microbes carried by ballast water have led to serious damage, the skill of ultraviolet collaborative ultrasonic is efficient and pollution-free. Using this kind of technology, it designed the sterilization, including tubes selection, UV doses calculation, cylinder body design, US power and frequency design, US transducer selection etc. After the experiment of inactivated algae the results show that this kind of technology is feasible in ballast water treatment.

Abstract: A halotolerant and highly effective phenol-degrading strain, named as JDD1H, was isolated from soil contaminated by petroleum and identified as Rhodococcus sp. Phenol degradation by strain JDD1H in the presence of high salinity, especially the effect of exotic stimulants such as carbon source, nitrogen source and surfactant on phenol degradation was investigated. The results show that strain JDD1H could utilize phenol as sole carbon and energy source to grow in the presence of 5% NaCl with 16 h adaptive phase. The degradation efficiency of 150 mg/L phenol was up to 99.5% within 40 h. Lactose, cane sugar, glucose and mannitol in wide range of 100~2000 mg/L enhanced phenol degradation significantly. Organic nitrogen sources, as peptone and yeast extract, and inorganic nitrogen sources, as NH4Cl and (NH4)2SO4, accelerated phenol degradation. Tween-80 with concentration of 50-1000 mg/L restrained phenol degradation and Tween-80 of 1500-2000 mg/L could promote degradation.

Abstract: It tends to produce high-turbidity raw water during the initial period of typhoons or storms and affect the operation of the purifying system. In this research, the particles size (D98) in raw water was 100–125 μm; that in effluent water was <25 μm. When was under 8 ml/s, effluent water D98 was <10 μm. Flow ratio mitigation and the increase of overflow level can improve the particle removing ratio In aspect of particle size analysis, optimal operating conditions can be achieved setting an 8 ml/sec and 40cm overflow level and D98 grain size can be reduced to 6.25μm as well, particle size removal ratio will gradually climb with the increase of accumulated percentage so that it can reach 70 % for the respective effluent water under D50 and even becomes over 80 % under D98. When under D90, the removing ratio can even go beyond 90 % at an 8 ml/s of flow ratio. Therefore, the proposed pre-treatment reduces high turbidity due to the sudden increase of raw water to the barrier in front of the board.