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1.
This study has investigated how to simultaneously remove both heavy metals (Cu, Mn, and Zn) and natural organic matters (NOM; humic acid and fulvic acid) from river water using potassium ferrate (K2FeO4), a multipurpose chemical acting as oxidant, disinfectant, and coagulant. In water sample including each 0.1 mM heavy metal, its removal efficiency ranged 28–99% for Cu, 22–73% for Mn, and 18–100% for Zn at the ferrate(VI) doses of 0.03–0.7 mM (as Fe). The removal efficiency of each heavy metal increased with increasing pH, whereas an overall temperature did not make any special effect on the reaction between the heavy metal and ferrate(VI). A high efficiency was achieved on the simultaneous treatment of heavy metals (0.1 mM) and NOM (10 mg/l) at the ferrate(VI) doses of 0.03–0.7 mM (as Fe): 87–100% (Cu), 31–81% (Mn), 11–100% (Zn), and 33–86% (NOM). In the single heavy metal solution, the optimum ferrate dose for treating 0.1 mM Cu or Mn was 0.1 mM (as Fe), while that for treating 0.1 mM Zn was 0.3 mM (as Fe). In the mixture of three heavy metals and NOM, on the other hand, 0.5 mM (as Fe) ferrate(VI) was determined as an optimum dose for removing both 0.1 mM heavy metals (Cu, Mn, and Zn) and 10 mg/l NOM. Prior to the addition of ferrate(VI) into the solution of heavy metals and NOM (HA or FA), complexes were formed by the reaction between divalent cations of heavy metals and negatively charged functional groups of NOM, enhancing the removal of both heavy metals and NOM by ferrate(VI).  相似文献   

2.
In this research, we have investigated the removal efficiency of natural organic matter (NOM) from river and stream water using potassium ferrate(VI). For the study, ferrate was added in 100-ml water sample mixed either with humic acid or with fulvic acid. The removal efficiency at the ferrate dose of 2–46 mg/l (as Fe) was 21–74% for 10 mg/l humic acid and 48–78% for 10 mg/l fulvic acid. NOM was more effectively removed either at lower pH or at higher temperature. The removal performance by ferrate was comparable to that by traditional coagulants (i.e., alum, FeSO4·7H2O, and FeO(OH)). In addition, the removal rate of humic acid using traditional coagulants was improved by pretreatment with a very small dose of ferrate. The reaction between ferrate and humic acid was completed within 60 s, while showing first-order kinetic, and then reached a steady state.  相似文献   

3.
The performances of a new and a mature integrated constructed wetland (ICW) system treating domestic wastewater were evaluated for the first time. The new ICW in Glaslough (near Monaghan, Ireland) comprises five wetland cells, and the mature system in Dunhill (near Waterford, Ireland) comprises four cells. The performance assessment for these systems is based on physical and chemical parameters collected for 1 year in Glaslough and 5 years in Dunhill. The removal efficiencies for the former system were relatively good if compared to the international literature: biochemical oxygen demand (BOD, 99.4%), chemical oxygen demand (COD, 97.0%), suspended solids (SS, 99.5%), ammonia nitrogen (99.0%), nitrate nitrogen (93.5%), and molybdate-reactive phosphorus (MRP, 99.2%). However, the mature ICW had removal efficiencies that decreased over time as the Dunhill village expanded rapidly. The mean removal efficiencies were as follows: BOD (95.2%), COD (89.1%), SS (97.2%), ammonia nitrogen (58.2%), nitrate nitrogen (?11.8%), and MRP (34.0%). The findings indicate that ICW are efficient in removing BOD, COD, SS, and ammonia nitrogen from domestic wastewater. Moreover, both ICW systems did not pollute the receiving surface waters and the groundwater.  相似文献   

4.
The present study aims to investigate the performance of potassium ferrate(VI) in treating decentralized domestic sewage from a rural scattered residential area. Major results were that around 90% of total phosphorus (TP) and 40% of chemical oxygen demand (COD) could be reduced when 25 mg L?1 of ferrate(VI) was applied. The removal of ammonia and total nitrogen (NH3–N and TN) was also monitored. However, the nitrogen removal during the chemical dosing was rather low. Big fluctuations of removal rates were observed against shock pollutants concentrations. Considering its strong ability in removing emerging organic pollutants and P, ferrate(VI) is competitive in the treatment of decentralized domestic sewage as an advanced treatment unit following some traditional treatment units.  相似文献   

5.
Jiang  J.-Q.  Zeng  Z.  Pearce  P. 《Water, air, and soil pollution》2004,158(1):53-65
The modification and use of clays as coagulants for wastewater treatment were investigated in this study. The raw clays were montmorillonites K10 and KSF, and were modified by polymeric aluminium (Al) or ferric (Fe) and/or Al/Fe mixed polymeric species. The comparative performance of modified clays and aluminium sulphate and ferric sulphate were evaluated in terms of the removal of turbidity, suspended solids, UV254-abs., colour, and total and soluble CODs. The results demonstrated that after being modified with mixed polymeric Al/Fe species, two montmorillonite clays possess greater properties to remove the particles (as suspended solids) and organic pollutants (as COD and UV254-abs.) from the wastewater and to enhance the particle settling rate significantly.  相似文献   

6.
Simultaneous power generation and fecal wastewater treatment were investigated using a combined ABR-MFC-MEC system (anaerobic baffled reactor-microbial fuel cell-microbial electrolysis cell). The installation of multi-stage baffles can benefit retaining the suspended solids in the system and help separate the hydrolysis-acidification and the methanogen processes. The efficiencies of the nitrification-denitrification process were improved because of the weak current generation by coupling the microbial electrochemical device (MFC-MEC) with the ABR unit. Maximum removal rates for chemical oxygen demand (COD) and ammonia nitrogen (NH4 +-N) were 1.35 ± 0.05 kg COD/m3/day and 85.0 ± 0.4 g NH4 +-N/m3/day, respectively, while 45% of methane (CH4), 9% of carbon dioxide (CO2), and 45% of nitrogen gas (N2) contents in volume ratio were found in the collected gas phase. An average surplus output voltage of 452.5 ± 10.5 mV could be achieved from the combined system, when the initial COD concentration was 1500.0 ± 20.0 mg/L and the initial NH4 +-N concentration was 110.0 ± 5.0 mg/L, while the effluent COD could reach 50.0 mg/L with an HRT of 48 h. The combined process has the potential to treat fecal wastewater efficiently with nearly zero energy input and a fair bio-fuel production.  相似文献   

7.
Constructed wetlands have recently received considerable attention as low cost and efficient means of cleaning up many different types of wastewaters at secondary and tertiary levels. This is an environmentally sound method of wastewater treatment that does not use hazardous chemicals, and is based on the high productivity and nutrient removal capability of the wetland that strongly relies on its intricate ecosystem structure and function. Research work was conducted on a tropical constructed wetland to establish its capability to treat wastewater during the dry season. A comparison of its efficacy with that of conventional wastewater treatment plants was made on the basis of the measured water quality parameters. Temperature, pH, dissolved oxygen, and conductivity were measured in situ. Total suspended solids (TSS), total dissolved solids (TDS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), phosphorus, ammonia, and nitrites were analyzed in the laboratory. Fecal coliforms were enumerated and Escherichia coli counts were determined. The TSS values reduced from a mean of 102 mg/l at the influent point to 16 mg/l at the effluent point, depicting a reduction of 84.3%. Influent TDS averaged 847 mg/l, while the effluent averaged 783 mg/l. Dry season BOD5 levels were reduced from an average of 286 at the inlet point to 11 mg/l at the outlet representing a reduction efficiency of 96.2%. COD levels were reduced from a mean of 2,002.5 to 47.5 mg/l depicting a removal efficiency of 97.6%. Phosphorus was reduced from a mean of 14 to 11 mg/l representing a percentage removal of 21.4%. Levels of ammonia reduced from a mean of 61 at the influent point to 36 mg/l at the effluent point representing a percent reduction of 41.0%. There was a 99.99% reduction for both the fecal coliforms and E. coli counts. Conductivity of wastewater increased from 1.08 to 1.98 mS, while the pH increased from 6.23 at the inlet point to 7.99 at the outlet of the system. Temperature and dissolved oxygen measurements showed a diurnal variation. The dry season wastewater heavy metal concentrations were in the following ranges: Pb (0.7?C6.9 ppm), Cr (0.2?C0.5 ppm), Zn (0.1?C2.3 ppm), Ni (0.1?C1.3 ppm) with Cd and Cu not being detected in the wastewater streams. Overall, tropical constructed wetlands are effective in treating wastewater streams and they perform a lot better than the popularly used waste stabilization ponds. This paper recommends that they can be widely used within the tropics.  相似文献   

8.
Two experimental ponds, with an effective volume of 2 m3 each, were constructed in a workshop at the textile plants to investigate the potential for a stabilization pond for purification of textile wastewater. Parametric analysis of pH, temperature, turbidity suspended solids, total suspended solids, DO, BOD, COD, N, and algae was carried out on the influent and the effluent according to the procedures recommended by the standard methods (APHA, 1971). Considering the results obtained from tests after daily observations, the application of an oxidation pond for treatment of textile wastewaters in the winter time was not promising. The ponds had a little activity in aerobic condition. In other seasons the ponds were efficient and the removal of BOD, COD, and N was 81, 78, 72% respectively, with a loading rate of 7.950 g BOD m?2 day?1 and detention time of 20 days. The ponds were usually saturated and sometimes super-saturated with dissolved O2. The experimental ponds were put to work in series for BOD, COD, and N removal observation. The removal did not improve compared with a single pond and algae concentration was noticeably reduced in the effluent.  相似文献   

9.
猪场废水厌氧消化液后处理技术研究及工程应用   总被引：34，自引：9，他引：34  
猪场废水经过厌氧消化后，可生化性变差，BOD5/COD仅为0.19，并且碳、氮倒置，比例严重失调，给后续好氧处理带来很大困难。采用序批式活性污泥法(SBR)工艺直接处理厌氧消化液，污染物的去除效果很差，COD仅去除8.31%，NH3-N去除78.7％。通过改善厌氧消化液的可生化性和培养高效脱氮菌种等措施，COD、NH3-N去除率改善显著，COD、BOD5与SS的去除分别达到89.6%～93.4%、97.9%，95.6%，特别是对NH3-N，达到了99%以上去除效率。将实验室结果应用于实际工程，也取得了好的效果，工程上SBR系统对猪场废水厌氧消化液的COD去除90%左右，出水COD基本上在300 mg/L以下。NH3-N去除率大于99%，出水NH3-N小于10 mg/L。BOD5去除率大于98%，出水BOD5小于20 mg/L。TN去除率大于90%。  相似文献   

10.
Arsenic, lead, and phosphorous contamination in soils represents a health risk. Chitosan (poly-N-acetyl glucosamine) inexpensive by-product derived from chitin has been used as a metals adsorbent. Objectives of this research were to evaluate the effectiveness of chitosan solution for arsenic, lead, and phosphorous extraction from lead-arsenate contaminated soils, and evaluate the effectiveness of protonated chitosan flakes (PCF) and ferric hydroxide chitosan beads (Fe(III)-CB) for water-soluble As removal from these soils. Percentage of arsenic, lead, and phosphorous removed from the soils by chitosan solution ranged from 0.96% to 17%, 1.80% to 31%, and 0.66% to 11%, respectively. Percentage of water-soluble arsenic removed by PCF and by Fe (III)-CB ranged from 12% to 47% and 36% to 77%, respectively. Averaged over soils, Fe (III)-CB removed slightly more arsenic (As) (42 mg kg?1) compared to Mehlich III (40 mg kg?1) extractant. Results indicate potential for the use of chitosan as an extraction for lead-arsenate contaminated soils.  相似文献   

11.
Cattle manure vermicompost has been used for the adsorption of Al(III) and Fe(II) from both synthetic solution and kaolin industry wastewater. The optimum conditions for Al(III) and Fe(II) adsorption at pH?2 (natural pH of the wastewater) were particle size of ≤250?µm, 1 g/10 mL adsorbent dose, contact time of 4 h, and temperature of 25°C. Langmuir and Freundlich adsorption isotherms fitted reasonably well in the experimental data, and their constants were evaluated, with R 2 values from 0.90 to 0.98. In synthetic solution, the maximum adsorption capacity of the vermicompost for Al(III) was 8.35 mg g?1 and for Fe(II) was 16.98 mg g?1 at 25°C when the vermicompost dose was 1 g 10 mL?1, and the initial adjusted pH was 2. The batch adsorption studies of Al(III) and Fe(II) on vermicompost using kaolin wastewater have shown that the maximum adsorption capacities were 1.10 and 4.30 mg g?1, respectively, at pH?2. The thermodynamic parameter, the Gibbs free energy, was calculated for each system, and the negative values obtained confirm that the adsorption processes were spontaneous.  相似文献   

12.
This study evaluated the effectiveness of a novel adsorbent (Fe(III)-AM-PGMACell), Iron(III)-coordinated amino-functionalized poly(glycidyl methacrylate)-grafted cellulose for the adsorption of arsenic(V) from aqueous solutions. The Fe(III)-AM-PGMACell was prepared through graft copolymerization of glycidyl methacrylate (GMA) onto cellulose (Cell) in the presence of N,N??-methylenebisacrylamide (MBA) as a cross linker using benzoyl peroxide initiator, followed by treatment with ethylenediamine and ferric chloride in the presence of HCl. Batch experiments were performed to evaluate the adsorption efficiency of Fe(III)-AM-PGMACell towards As(V) ions. The contact time to attain equilibrium and the optimum pH were 90?min and 6.0, respectively. More than 99.0% adsorption was achieved from an initial concentration of 25.0?mg/L. A two-step pseudo-first-order kinetic model agreed well with the dynamic behavior for the adsorption process. Equilibrium data fitted well with Sips isotherm model with maximum adsorption capacity of 78.8?mg/g at 30??C. The desorption of As(V) was achieved over 98.0% with 0.1?M NaCl solution.  相似文献   

13.
Attempt has been made to study the treatability of printing ink wastewatergenerated from an Indian currency printing press using coagulation-flocculation process. Coagulant agents, viz. ferrous sulphate, ferric chloride, aluminium sulphate and polyaluminium chloride were studied to select the most suitablecoagulant for effective treatment, and attain the optimum coagulant concentration. Cationic polyeletrolyte in conjunction with the most effective coagulant was also studied to assess its effect on floc settleability. Polyaluminium chloride (PAC) was found to be the most efficient coagulant, achieving removals of colour, suspended solids (SS), biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of 95.9–96.5%, 96.5–97.0%, 61.3–65.8%and 54.8–61.8%, respectively at an optimum concentration of 1500 mg L-1. Other coagulants, viz. ferrous sulphate, ferric chloride and aluminium sulphate did not show substantial removals of colour, BOD and COD, except suspended solids in comparison to the performance of PAC. Cationic ploylectrolyte in combination with PAC at an optimum concentration of 1500 mg L-1 of PAC and 1.0 mg L-1 of polyelectrolyte further improved the removal efficiency of various parameters studied, in addition to improving the floc settling rate, and reduction in quantity of sludge generation.Effect of rapid mixing intensity expressed as mean temporal velocity gradient (G), and mixing time (t) on flocculation was also investigated. Rapid mixing at an impeller rotational speed (n) of 300 rpm and mixing time (t) of 60 sec indicated good floc formation, which resulted in achieving velocity gradient of 821 s-1, and was found to be an optimum combination. This was also indicated by relatively high settling velocity of sludge formed and low residual colour in the supernatant. However, slow mixing beyond 5 min, adopted after initial optimum rapid mixing, indicated negligible effect on flocculation.  相似文献   

14.
The selectivity and uptake capacity of horticultural peat available in Romania was evaluated with respect to the removal of Cd(II), Cr(VI) and Pb(II) ions from aqueous solution. The kinetics, sorption capacities, selectivity and pH dependence of sorption were determined. The influence of metal concentration in solution is discussed in the terms of Langmuir and Freundlich isotherm and constants. Sorption capacities increased with increasing metal concentration in solution. For solutions containing 300 mg/l of metal, the observed uptake capacities were 20 mg Cd(II)/g peat, 15 mg Cr(VI)/g peat and 30 mg Pb(II)/g peat. The study proved that horticultural peat is a suitable material for the removal of the studied heavy metal ions from aqueous solutions, achieving removal efficiencies higher than 90%, and could be considered as a potential material for treating effluent polluted with Cd(II), Cr(VI) and Pb(II) ions.  相似文献   

15.
To probe the effect of common coexist substances on the nitrate removal by polymeric resin supported nanoscale zero-valent iron composite (D201-nZVI), humic acid (HA) was added into the nitrate removal system to elaborate the different interactions between each two and among all in the system including HA, nitrate, and D201-nZVI. The results showed that the effect of HA on the reduction of nitrate by D201-nZVI was concentration-dependent. At low HA concentration (<?5 mg/L), HA coating formed by the HA adsorption on the surface of the nZVI particles enhanced the dispersion of the particles, which led to a more evenly distribution of nZVI particles in the solution, and thus a higher nitrate reduction activity. When HA concentration was increased to 5 mg/L or more, the competitive adsorption of HA and NO3? on the surfaces of the D201-nZVI dominated, and the nitrate removal rate and ammonia nitrogen production were decreased. When the HA concentration reached to a further high level (>?20 mg/L), HA acted as an electron shuttle to accelerate the reduction of Fe(III) to Fe(II) in the D201-nZVI, and thus the nitrate reduction rate was accordingly enhanced. The ammonia production increased by 24.8% at HA concentration of 40 mg/L as compared with that of the control (without addition of HA). This research elucidated the interaction of HA within different HA concentration in the complicate system of anions removal by organic support-nanoscale metal particle composite, which may shade some new light on the potential application of nanoscale zero-valent materials in the practical remediation of natural water.  相似文献   

16.
In this study, dissolved air flotation (DAF) was examined as a possible treatment method for the removal of chromium from aqueous solution and plating wastewater. Two coagulants, ferric chloride and poly aluminum chloride (PAC), were used for pretreatment of wastewater. Maximum removal of chromium was achieved for poly aluminum chloride (98 %). Artificial neural network was used for the prediction of the DAF system. The best neuron used for the prediction of chromium removal percentage of interpolated wastewater was 6 %. The mean score error and the coefficient correlation were 0.0007542 and 0.997, respectively.  相似文献   

17.
Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.  相似文献   

18.
Fe2O3-TiO2/UV/O3+PSAF协同处理猪场废水效果及其除碳脱氮机制   总被引：2，自引：2，他引：0  
为实现低碳高氨氮猪场废水深度除碳脱氮,该研究提出了 Fe_2O_3-TiO_2/UV/O_3+PSAF组合处理工艺技术。应用响应面法确立了组合工艺的最优工况条件,采用三维荧光和紫外-可见吸收光谱分析了有机物的荧光和分子结构变化特征,并结合碳、氮形态变化探明了其协同处理特性及除碳脱氮机制。结果表明,Fe_2O_3-TiO_2投加量为1.06 g/L、O_3流量为3.02 g/h、曝气时间为90.75 min、聚硅酸铝铁(PSAF)用量为833.29 mg/L,COD及NH_(3-)N去除效果最好,试验值与预测值偏差0.75%和0.56%,拟合性良好;组合工艺对猪场废水中的溶解性微生物代谢产物和类腐殖质处理效果显著,溶解性有机碳和总溶解性氮去除率分别达77.7%和82.6%,协同因子分别为1.11和1.50。其中,Fe_2O_(3-)TiO_2/UV/O_3对类腐殖质削减效果显著,O_3和·OH协同氧化类腐殖质、NH_3-N为小分子物质、NO_3~--N和N_2 (N_2转化率达39.71%),提高了富氧官能团的数量,促进了氮素的转化和矿化,利于PSAF对小分子物质和NO_3~--N等污染物的去除,组合工艺协同互补作用明显。研究结果为深度处理低碳高氨氮有机废水提供一种新思路。  相似文献   

19.
Atrazine-contaminated soil may require remediation to mitigate ground and surface water contamination. We determined the effectiveness of nano zerovalent iron (nano ZVI) to dechlorinate atrazine (2-chloro-4ethylamino-6-iso-propylamino-1,3,5-triazine) in contaminated water and soil. This study determined the effects of iron sources, solution pH, Pd catalyst and presence of Fe or Al sulfate salts on the destruction of atrazine in water and soil. Our results indicate nano ZVI can be successfully used to remediate atrazine in water and soil. Aqueous solution of atrazine (30 mg l?1) was treated with 2% (w/v) of nano ZVI and 5% (w/v) of commercial ZVI. Although, iron dose in nano ZVI treatment was less than that in commercial ZVI treatment, atrazine destruction kinetic rate (k obs) of nano ZVI treatment (1.39 days?1) was around seven times higher than that of commercial ZVI treatment (0.18 days?1). Reductive dechlorination was the major process in destruction of atrazine by nano ZVI. The dechlorination product was 2-ethyl-amino-4-isopropylamino-1,3,5-triazine. Lowering the pH from 9 to 4 increased the destruction kinetic rates of atrazine by nano ZVI. Moreover, nano ZVI/Pd enhanced destruction kinetic rates of atrazine (3.36 day?1). Pd played the important role as a catalyst during treatment of atrazine by nano ZVI. Atrazine destruction kinetic rates were greatly enhanced in both contaminated water and soil treatments by nano ZVI when sulfate salts of Fe(II), Fe(III) or Al(III) was add with the following order of removal rates: Al (III) (2.23 day?1) > Fe (III) (2.04 day?1) > Fe(II) (1.79 day?1). The same results were found in atrazine-nano ZVI-soil incubation experiments.  相似文献   

20.
This study investigates the microalgal community dynamics associated with changes in municipal wastewater quality and discharges from the dairy industry in central Veracruz, Mexico, using an experimental stabilization-reactors system. Thirty one species of microalgae were recorded and 15 physicochemical variables were measured daily over 25 days in pretreated water. The biomass of microalgal groups displayed significant negative correlations with biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspend solids (TSS). Conversely, a significant positive correlation was found with dissolved oxygen, pH and nitrates. Using the Canonical Correspondence Analysis we identified an initial anaerobic phase (Phase I), characterized by high BOD, TSS and COD, ammonium and faecal coliforms. This was followed by a transition phase (Phase II), an initial aerobic phase (Phase III), when water quality improved considerably, and finally an aerobic phase (IV) with a high percent reduction in these parameters and almost complete organic load removal. The most abundant species associated with these phases were Arthrospira jenneri (Cyanophyceae) and Coccomonas sp. (Chlorophyceae) in Phase I; Polytomella sp. (Chlorophyceae) in Phase II; Polytoma tetraolare, Chlamydomonas caeca (Chlorophyceae) and some Cyanophyceae including Geitlerinema, Synechocystis, Cyanobium and Glaucospira in Phase III; Carteria sp. (Chlorophyceae), Lepocynclis ovum and Euglena clavata (Euglenophcyeae) in Phase IV. Maximum richness, diversity, and biomass levels occurred during the aerobic phase. Similar to other wastewater treatment systems the high succession rates decreased with reactor stabilization. These findings provide statistical evidence on the suitability of certain microalgae species as indicators of wastewater stabilization reactor status and effluent quality.  相似文献   

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