Advanced Materials Research Vols. 610-613

Abstract: As a sewage disposal system, a biological combination system of constructed wetlands and sand filters was set up to develop the technology, to improve the disposal performance, to offer the theoretical foundation and technical parameters for realizing the standardized engineering construc- tion. The results show that: 1) The system shows certain removal efficiency to CODCr, TN, NH4-N and TP, however because of the limited space on the bank, the results are not so satisfying.2) Among the aquatic plants selected on the principle of native species, Water Celery, Canna Generalis, Iris and Ranunculus Sceleratus can grow very well.3) The revetments make the DO rise by about 5~7mg/L, of which ecological board revetment has the best re-oxygenation performance.

Abstract: Based on the investigation of odor concentration of retention tank in combined system, it aim at the removal of mixed odor and pressure drop with blast furnace slag, pebble, sand as improved medium and soil as contrast through mixed odor of ammonia gas and hydrogen sulfide made in lab-scale. The results showed that the removal rate of H2S by different medium packed column becomes stable after 12 days, and 35 days for NH3. Pressure drop of each column meets with Equation Ergum and under the same condition the order is as follows: soil>sand>pebble>blast furnace slag. And the removal rate of each medium is: soil>sand>blast furnace slag. The soil is good for removal but its pressure drop is so high that it limits flow charge, thus its removal rate is the lowest. As a result, sand and pebble as the medium for soil deodorization considering pressure drop and the effect of deodorization were chosen. It turns out that the removal rate of NH3 is higher than 65% while H2S higher than 98%.

Abstract: The statistics about investment and operation situation of 36 urban sewage treatment plants and 72 country ones show that: ①Urban and country sewage treatment plants are mainly small-scale ones, using oxidation ditch, A2/O, SBR and its variants process. ②Operation loading rates of urban and county sewage treatment plants are generally low, and the better treatment process varies with different scales. ③The unit investment and unit investment of pipe network decreases with the scale increasing. So does the trend of operating cost. Overall, the operating costs of the A2/O and the oxidation ditch are cheaper in urban wastewater treatment plants, while each process are more economical in country ones. Therefore, choosing reasonable process, and coordinating the relationship between centralization and decentralization play an irreplaceable role in the coordinated development of the Guangxi autonomous region in the future, saving money under the premise of ensuring the safety of water environment.

Abstract: Geometry optimization is an effective method to improve the hydraulic efficiency of an ozone contactor. The enhancement of hydraulic efficiency can lead to a smaller dose of ozone and thus minimizing the potential risk caused by disinfection by-products. Unlike adding some extra structures in geometries in previous studies, optimization for water outlet was applied to improve the hydraulic efficiency in this paper. The water outlet was modified to several parallel flumes arranged uniformly on the top of the contactor from overflow weir. In a typical contactor with diffusers, the effect of water outlet optimization on system performance was studied based on computational fluid dynamics employing a two dimensional Euler model coupled with species transport model and discrete particle model. The T10/HRT, the most common indicator of hydraulic efficiency, was improved by 10%-24% with less short-circuiting after optimization. Compared to the original geometry, optimization for water outlet brought about a 19.6% increase in log inactivation, which represents the disinfection efficiency. To maintain the same Cryptosporidium inactivation efficiency after the water outlet optimization, ozone dosage could be reduced by 18% from 2.0 mg/L to 1.64mg/L, which resulted in a minimization of bromate formation by 8.90%.

Abstract: Used A/O-SBR(anaerobic/aerobic alternating enhanced biological phosphorus removal system) to study carbon source and phosphate accumulating organisms (PAO) intracellular energy storage substance transformation, also studied PAO’s phosphorus removal capacity. PAO could uptake quick degradation organic matters and synthesis polyhydroxyalkanoates(PHA). PHA was a kind of intracellular energy storage substance, its content could affect PAO’s phosphorus removal capacity. When carbon source was plentiful, PAO could synthesis a lot of PHA, phosphorus removal capacity could reach 38.16 mgp/gvss. Sludge retention time could affect PAO synthesis PHA of quantity and structure. Along with the sludge retention time growth, intracellular PHA content was increased, and phosphorus uptake of desired aerobic time continues to decrease, so increasing the phosphorus removal efficiency. When the municipal sewage as carbon source, PHA was mainly composed of PHB(poly-ß-hydroxyvalerate) and PHV(poly-ß-hydroxyvalerate). Along with the sludge retention time prolongation, PAO could synthesis more PHV, PHB content was remain unchanged, PHA composition structure was changed.

Abstract: this review summarizes an important factor of clogging in subsurface flow constructed wetlands ¬(SSF)—field distribution. The efficiency of filter media and the spatial distribution of biological growth are determined by the flow field distribution directly. If the flow field distribution is un-uniform, it would accelerate the clogging of substrate. The influencing factors for flow field distribution, including hydraulic loads, properties of filter media, filling structures and root distribution were investigated, and the clogging reasons were discussed additionally. At last, this study showed some corresponding research methods, and helping in the process of research and development of subsurface flow constructed wetlands in solving clogging problem.

Abstract: Radial oxygen loss (ROL) from roots of reed, typha and wild rice stem was investigated. Root excretion oxygen showed that the rates of the ROL increased with the illumination time under hard light intensity. For each plant, the ability that roots excreting oxygen under different light intensities decreased successively in the order of hard light, non-light and weak light. The ROL was different with the increased sequence of typha, wild rice stem and reed. The local available reed and typha could remove the pollutants effectively in the pilot test with the average removal rates of 41.99%, 28.47%, 48.38% and 48.76%, respectively.

Abstract: To improve phytoremediation efficiency of aged polycyclic aromatic hydrocarbons (PAHs), in-situ experiment was conducted in the Shenfu wastewater irrigation district in northeast China. Several strengthen measures, including microbe agent, farmyard manure, N-fertilizer, fungi, were taken. The results showed strengthen measures increased of PAHs to alfalfa and ryegrass were 46.36% and 51.12%. The removal rate of 35.98% and 37.54% were achieved for the removal to 5-6 rings PAHs. In-situ experiment proved that strengthened phytoremediation didn’t cause the accumulation of PAHs in inside plant bodies, and it could be used in the farm soil contaminated with PAHs.

Abstract: Degradation of phenol was studied in the presence of Fenton Reagent. The initial concentrations of C2O42, H2O2 , Fe2 + and pH value on the reaction were investigated. The optimum conditions to degrade phenol from water were determined when initial phenol concentration was 500mg/L, the concentration of Na2C2O4, H2O2 and Fe2 + were 0mmol/L, 300mg/L and 60mg/ L respectively, and pH value was 3. Under the optimum conditions, phenol degradation and mineralization rates could reach 80% and 50%, respectively when the degrade time lasted 10 min.Reference to other literature of sodium oxalate to join can effectively improve the utilization of the ultraviolet and visible light,thus enhancing the effect of high concentrations of phenol wastewater removal, but this experiment reflects the high C2O42- will play an inhibitory effect .

Abstract: The Fe/Cu catalyzed inner electrolysis system was used to treat actual mixed wastewater to evaluate the ecological safety and feasibility of the technology. The pretreatment by the Fe/Cu process removed 30% of COD, which reduced the loading rate of the subsequent biological treatment. Meanwhile, BOD5/COD ratio was increased by about 160%, which created favorable conditions for the subsequent biological treatment. The results indicated that the optimal mass ratio of Fe and Cu was 4:1, the technology covered wider pH range: the wastewater responded well to the reduction when the influent pH changed from 4 to 8, the reaction times was 120 min. Furthermore, the consumption of iron was low. All these led to an easy maintenance and low operating cost.