0
selected
-
1.
Coagulation behavior and floc characteristics of a novel composite poly-ferric aluminum chloride-polydimethyl diallylammonium chloride coagulant with different OH/(Fe3+ + Al3+) molar ratios.
Sun, C, Qiu, J, Zhang, Z, Marhaba, TF, Zhang, Y
Water science and technology : a journal of the International Association on Water Pollution Research. 2016;(7):1636-1643
Abstract
In this paper, flocculating performance and mechanisms of a new composite coagulant, poly-ferric aluminum chloride-polydimethyl diallylammonium chloride (PFAC-PD) with different OH-/(Fe3+ + Al3+) molar ratios, were investigated for humic acid (HA)-kaolin synthetic wastewater treatment. The impact of OH-/(Fe3+ + Al3+) molar ratios on the removal efficiencies of turbidity and dissolved organic carbon, specific UV absorbance, coagulation mechanisms and dynamics was explored during the coagulation process using composite coagulants. The coagulation experimental results revealed that the composite coagulants with lower OH-/(Fe3+ + Al3+) molar ratio exhibited better coagulation efficiency. When OH-/(Fe3+ + Al3+) molar ratio of the composite coagulant was 1.5, adsorption-bridging played a dominant role in coagulating HA-kaolin synthetic wastewater. The floc growth rate and floc size, increased with increasing OH-/(Fe3+ + Al3+) molar ratio and the highest peak height of the size distribution was obtained by PFAC-PD with OH-/(Fe3+ + Al3+) = 1.5. Also, the composite coagulants with higher OH-/(Fe3+ + Al3+) molar ratio formed more compact flocs, as reflected by the higher fractal dimension value. The flocs coagulated by PFAC-PD with basicity value of 1.0 gave strong strength and good recoverability.
-
2.
Stimulation of methanogenesis in anaerobic digesters treating leachate from a municipal solid waste incineration plant with carbon cloth.
Lei, Y, Sun, D, Dang, Y, Chen, H, Zhao, Z, Zhang, Y, Holmes, DE
Bioresource technology. 2016;:270-276
Abstract
Bio-methanogenic digestion of incineration leachate is hindered by high OLRs, which can lead to build-up of VFAs, drops in pH and ultimately in reactor souring. It was hypothesized that incorporation of carbon cloth into reactors treating leachate would promote DIET and enhance reactor performance. To examine this possibility, carbon cloth was added to laboratory-scale UASB reactors that were fed incineration leachate. As expected, the carbon-cloth amended reactor could operate stably with a 34.2% higher OLR than the control (49.4 vs 36.8kgCOD/(m3d)). Microbial community analysis showed that bacteria capable of extracellular electron transfer and methanogens known to participate in DIET were enriched on the carbon cloth surface, and conductivity of sludge from the carbon cloth amended reactor was almost twofold higher than sludge from the control (9.77 vs 5.47μS/cm), suggesting that microorganisms in the experimental reactor may have been expressing electrically conductive filaments.
-
3.
Assessing the energy and environmental performance of algae-mediated tertiary treatment of estrogenic compounds.
Colosi, LM, Resurreccion, EP, Zhang, Y
Environmental science. Processes & impacts. 2015;(2):421-8
Abstract
This study uses a systems-level modeling approach to illustrate a novel synergy between municipal wastewater treatment and large-scale algaculture for production of bio-energy, whereby algae-mediated tertiary treatment provides efficient removal of unregulated, strongly estrogenic steroid hormones from the secondary effluent. Laboratory results from previously published studies suggested that algae-mediated treatment could deliver roughly 75-85% removal of a model estrogen (17β-estradiol) within typical algae pond residence times. As such, experimental results are integrated into a comprehensive life cycle assessment (LCA) framework, to assess the environmental performance of an algae-based tertiary treatment system relative to three conventional tertiary treatments: ozonation, UV irradiation, and adsorption onto granular activated carbon. Results indicate that the algae-mediated tertiary treatment is superior to the selected benchmarks on the basis of raw energy return on investment (EROI) and normalized energy use per mass of estrogenic toxicity removed. It is the only tertiary treatment system that creates more energy than it consumes, and it delivers acceptable effluent quality for nutrient and coliform concentrations while rendering a significant reduction in estrogenic toxicity. These results highlight the dual water and energy sustainability benefits that accrue from the integration of municipal wastewater treatment and large-scale algae farming.
-
4.
Characterization and adsorption mechanism of Zn2+ removal by PVA/EDTA resin in polluted water.
Zhang, Y, Li, Y, Yang, LQ, Ma, XJ, Wang, LY, Ye, ZF
Journal of hazardous materials. 2010;(1-3):1046-54
Abstract
Batch adsorption experiments were conducted using a PVA/EDTA resin as an adsorbent to adsorb Zn(II) ions from single component system in which experimental parameters were studied including solution pH, contact time, adsorbent dose and initial metal ions concentration. The equilibrium isotherms were determined at pH 6 under constant ionic strength and at different temperatures. The results showed that the maximum removal of Zn(II) (99.8%) with 1 g L(-1) of sorbent was observed at 40 mg L(-1) at an initial pH value of 6. Removals of about 60-70% occurred in 15 min, and equilibrium was attained at around 30 min. The equilibrium data for the adsorption of Zn(II) on PVA/EDTA resin was tested with various adsorption isotherm models among which three models were found to be suitable for the Zn(II) adsorption. In addition, the kinetic adsorption fitted well to the pseudo-second-order model and the corresponding rate constants were obtained. Thermodynamic aspects of the adsorption process were also investigated. Furthermore a higher desorption efficiency of Zn(II) from the PVA/EDTA resin using acid treatment was available by more than 95%.
-
5.
Development of a biomimetic enzyme-linked immunosorbent assay method for the determination of estrone in environmental water using novel molecularly imprinted films of controlled thickness as artificial antibodies.
Wang, S, Xu, Z, Fang, G, Zhang, Y, Liu, B, Zhu, H
Journal of agricultural and food chemistry. 2009;(11):4528-34
Abstract
We developed a fast and new direct competitive biomimetic enzyme-linked immunosorbent assay (BELISA) method for the determination of estrone in environmental water based on a novel molecularly imprinted film of controlled thickness as an artificial antibody. The imprinted film was directly synthesized on the well surface of MaxiSorp polystyrene 96-well plate by a room temperature ionic liquid-mediated chemical oxidative polymerization in conjunction with molecular imprinting technology. This novel film was characterized, and results showed that it exhibited an antibody-like binding ability, rapid adsorption speed, high stability, and hydrophilicity, which was particularly advantageous and suitable for BELISA development. This BELISA method had a higher selectivity for estrone than for the structurally related compounds, and competitive binding studies demonstrated various degrees of cross-reactivity with five estrogenic compounds ranging from 30 to 47%. Eighty minutes of analysis time was reduced when compared to that of traditional ELISA, while the imprinted film was able to be reused for more than 50 times without loss of sensitivity. The IC(50) (calculated as the concentration giving 50% inhibition of color development) and the detection limit values under optimized experimental conditions were 200 +/- 40 microg L(-1) and 8.0 +/- 0.2 microg L(-1), respectively. This developed method was applied to the determination of estrone in spiked environmental water samples with excellent recoveries ranging from 80 to 95%, and the results correlated well with that obtained using the high performance liquid chromatography method.
-
6.
Bioremediation of contaminated surface water by immobilized Micrococcus roseus.
Li, H, Li, P, Hua, T, Zhang, Y, Xiong, X, Gong, Z
Environmental technology. 2005;(8):931-9
Abstract
The problems caused by contaminated surface water have gradually become more serious in recent years. Although various remediation technologies were investigated, unfortunately, no efficient method was developed. In this paper, a new bioremediation technology was studied using Micrococcus roseus, which was immobilized in porous spherical beads by an improved polyvinyl alcohol (PVA) - sodium alginate (SA) embedding method. The experimental results indicated that COD removal rate could reach 64.7 % within 72 hours when immobilized M. roseus beads were used, which was ten times as high as that of free cells. The optimum inoculation rate of immobilized M. roseus beads was 10 % (mass percent of the beads in water sample, g g(-1)). Suitable aeration was proved necessary to enhance the bioremediation process. The immobilized cells had an excellent tolerance to pH and temperature changes, and were also more resistant to heavy metal stress compared with free cells. The immobilized M. roseus beads had an excellent regeneration capacity and could be reused after 180-day continuous usage. The Scanning Electronic Microscope (SEM) analysis showed that the bead microstructure was suitable for M. roseus growth, however, some defect structures should still be improved.