[Evaluation of Effect of Urban Non-point Source Pollution Control on Porous Asphalt-Bio-retention Combined Roads].

Different combinations of low impact development (LID) technologies can be applied for control of urban non-point source pollution. There are currently few evaluations of urban non-point source pollution and pollution load reduction based on a combination of porous asphalt and bio-retention. Taking Shenzhen International Low Carbon City as an example, road-deposited sediments were collected prior to and after rainfall events. Runoff was monitored under six typical rainfall events, from porous asphalt and the inlet/outlet of bio-retention. Through analysis of changes in the process of "build-up-wash-off-transport" of pollutant loads, the average build-up of road-deposited sediments in the study area was found to be (15.80±3.79) g·m-2; the mass percentage of road-deposited sediments (size>250 µm) was approximately 65.14%. The average wash-off percentage of six different intensity rainfall events was 17.15%, and road-deposited sediments (size<105 µm) were carried by 62.71%-74.94%. The average pollution loads of surface runoff pollutants SS, TN, and TP were 2.02, 0.025, and 0.0013 g·m-2, respectively. The removal rates of SS, TN, and TP through porous asphalt under infiltration and filtration were 70.26%, 46.29%, and 19.27%, respectively. The secondary purification removal rates of runoff water in bio-retention were 85.25%, 20.22%, and 70.27%, respectively. Pollutant loads into Dingshan River totaled 0.08, 0.011, and 0.0003 g·m-2, representing 4.05%, 43.47%, and 24.39% of runoff. The combination thus had a significant effect on runoff purification. Through quantitative research on the formation of non-point source pollution, this paper provides a scientific basis for estimating pollution loads of urban non-point source pollution and evaluating the performance of LID projects. It makes suggestions for the popularization and application of LID and sponge city design in China.

Feasibility and simulation model of a pilot scale membrane bioreactor for wastewater treatment and reuse from Chinese traditional medicine.

The lack and pollution of water resource make wastewater reuse necessary. The pilot scale long-term tests for submerged membrane bioreactor were conducted to treat the effluents of anaerobic or aerobic treatment process for the high-strength Chinese traditional medicine wastewater. This article was focused on the feasibility of the wastewater treatment and reuse at shorter hydraulic retention time (HRT) of 5.0, 3.2 and 2.13 h. MLSS growth, membrane flux, vacuum values and chemical cleaning periods were also investigated. The experimental results of treating two-phase anaerobic treatment effluent demonstrated that the CODfilt was less than 100 mg/L when the influent COD was between 500-10000 mg/L at HRT of 5.0 h, which could satisfy the normal discharged standard in China. The experimental results to treat cross flow aerobic reactor effluent demonstrated that the average value of CODfilt was 17.28 mg/L when the average value of influent COD was 192.84 mg/L at HRT of 2.13 h during 106 d, which could completely meet the normal standard for water reuse. The maximum MLSS and MLVSS reached 24000 and 14500 mg/L at HRT of 3.2 h respectively. Membrane flux had maximal resume degrees of 94.7% at vacuum value of 0.02 MPa after cleaning. Chemical cleaning periods of membrane module were 150 d. A simulation model of operational parameters was also established based on the theory of back propagation neural network and linear regression of traditional mathematical model. The simulation model showed that the optimum operational parameters were suggested as follows: HRT was 5.0 h, SRT was 100 d, the range of COD loading rate was between 10.664-20.451 kg/(m3xd), the range of MLSS was between 7543-13694 mg/L.

[Characteristics and operation of enhanced continuous bio-hydrogen production reactor using support carrier].

A kind of granular activated carbon, whose granular size is no more than 2mm and specific gravity is 1.54g/cm3, was used as the support carrier to allow retention of activated sludge within a continuous stirred-tank reactor (CSTR) using molasses wastewater as substrate for bio-hydrogen production. Continuous operation characteristics and operational controlling strategy of the enhanced continuous bio-hydrogen production system were investigated. It was indicated that, support carriers could expand the activity scope of hydrogen production bacteria, make the system fairly stable in response to organic load impact and low pH value (pH <3.8), and maintain high biomass concentration in the reactor at low HRT. The reactor with ethanol-type fermentation achieved an optimal hydrogen production rate of 0.37L/(g x d), while the pH value ranged from 3.8 to 4.4, and the hydrogen content was approximately 40% approximately 57% of biogas. It is effective to inhibit the methanogens by reducing the pH value of the bio-hydrogen production system, consequently accelerate the start-up of the reactor.

[Application of PCR-DGGE to resolve microbial diversity in bio-hydrogen producing reactor].

To reveal microbial diversity of anaerobic activated sludge in bio-hydrogen producing reactor, sludge in different period were sampled and their genomic DNA of microbial community was extracted directly. After purification of the genomic DNA using DNA gel recovery kit, the 16S rRNA genes (V3 region) were amplified by using the universal primers (F338GC and R534). The result of agarose gel (2%) electrophoresis show that the PCR products were about 200bp. These amplified DNA fragments were separated by denaturing gradient gel electrophoresis (DGGE) with the denaturant (urea and formamide) from 30% to 60%. The profile of DGGE show that different sludge had the different bands' patterns. In the profiles of DGGE, there exist some common bands in all sludge samples, which indicate that some kinds of microorganisms exist in each period. On the other hand, the specific bands in some sludge show that different period had their own specific microorganisms. Dynamics of community structure and amount of dominant populations were responsible to different period. Shift of microbial diversity correspond to period of running reactor, microbial diversity increased before it decreased. Similarity between communities gradually increased, speed of shift gradually decreased in succession. Finally, microbial climax community made up of specific populations was formed.

[Start-up and continuous operation of bio-hydrogen production reactor at pH 5].

A continuous stirred-tank reactor(CSTR)for bio-hydrogen production using molasses wastewater as substrate was investigated. Emphasis was placed on assessing the start-up and continuous operation characteristics when keeping pH value constant. It was found that at pH of 5, biomass of 6g/L, organic loading rate (OLR) of 7.0kg/(m3 x d) and a hydraulic retention time (HRT) of 6h, an equilibrial hydrogen-producing microbial community could be established within 30 days. Following that, oxidation redox potential (ORP) were kept within the ranges - 460mV - -480mV. Typical mixed acid type fermentation was exhibited in the reactor. Little difference was observed in the distribution of liquid end products. The liquid end products proportion of the total amount was 36% of acetic acid, 33% of ethanol, 18% of butyric acid, 13% of propionic acid and valeric acid, respectively. Hydrogen content in the biogas was about 30% - 35% . Maximal hydrogen production rate was 1.3m3/(m3 x d). The acid-producing fermentative bacteria were in the same preponderant status when the reactor showed mixed acid type fermentation. They are mostly cocci and bacilli.

[Continuous operation of hydrogen bio-production reactor with ethanol-type fermentation].

The natural response of a continuous stirred tank reactor (CSTR) for hydrogen bio-production using molasses wastewater as substrate was investigated. Emphasis was placed on assessing the operational controlling strategy on the stable operation of CSTR with high efficiency. It was found that at an initial biomass of 15g/L, an equilibrial microbial community in the ethanol-type fermentation and efficient stable operation of CSTR could be established with following conditions: temperature of 35 degrees C +/- 1 degrees C, COD organic loading rate (OLR) of 40kg/(m3 x d), hydraulic retention time (HRT) of 4h, pH value of 4.6 - 4.9 and oxidation reduction potential (ORP) of -450 - -470mV. Following that, hydrogen production in the reactor was relatively stable. The observed maximal hydrogen bio-production rate was 7.63m3/(m3 x d). The content of hydrogen in the biogas was about 40% - 58%. COD removal rate was between 22% - 26%. The total content of ethanol and acetic acid in the fermentative end products was above 80%.

[Application of denaturing gradient gel electrophoresis and temperature gradient gel electrophoresis in microbial molecular ecology].

In recent years, denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) are well-established molecular tools in microbial molecular ecology that allows the study of diversity and dynamics of microbial communities. The technique is reliable, reproducible rapid and inexpensive. Here, the principle, the limitations and potentials application of DGGE/TGGE techniques are introduced in this paper.