Feasibility Study on the Treatment of Wastewater Containing High-concentration Hg by Coagulation Sedimentation-Adsorption

For the wastewater containing high-concentration Hg,the feasibility of high-concentration Hg in wastewater treated by coagulation sedimentation,adsorption and the combined process was studied. Research results showed that if using the single coagulation sedimentation process,when FeSO_4·7H_2O dosage was 1. 39 g / L,and NaOH dosage was 0. 40 g / L,it could meet discharge requirement,but the reagent cost was 13. 1yuan / t,which was high. Because that there was subsequent adsorption process,it was selected 0. 28 g / L of FeSO_4·7H_2O and 0. 36 g / L of NaOH,and the estimated reagent cost was 2. 62 yuan / t. In selection process of adsorption materials,powdered activated carbon,granular activated carbon and diatomite all could effectively adsorb Hg,and the technology was feasible. When using the combined process of coagulation sedimentation + adsorption to treat the wastewater containing high-concentration Hg( 800 μg / L),removal rate could reach 99%,and operation cost was 2. 71 yuan. It could meet the requirement of sewage discharged into sewer( 20 μg / L) at the technology,and was acceptable at the economy.Therefore,treatment of wastewater containing high-concentration Hg by the combined process was feasible at the aspects of technology and economy.

Dynamic experiments on flocculation and sedimentation of argillized ultrafine tailings using fly-ash-based magnetic coagulant

In order to accelerate the sedimentation of super-large-scale argillized ultrafine tailings with bad features such as low settling velocity, muddy overflow water, and large flocculant dosage, a fly-ash-based magnetic coagulant （FAMC） was used in a dynamic experimental device. To obtain the best possible combination of the impact factors （magnetic intensity, FAMC dosage, flocculant dosage, and feed speed） for minimum overflow turbidity, a response surface methodology test coupled with a four-factor five-level central composite design was conducted. The synergy mechanism of FAMC and flocculant was analyzed based on the potential measurement and scanning electron microscopy. The results show that the flocculant dosage, overflow turbidity, and solid content can be reduced by 50%, 90%, and 80%, while the handling capacity per unit and efficiency of backfill and dry stacking can be promoted by 20%, 17%, and 13%, respectively, with a magnetic intensity of 0.3 T, FAMC dosage of 200 mL/t, flocculant dosage of 30 g/t, and feed speed of 0.6 t/（m^2·h）. Therefore, synergy of FAMC and flocculant has obvious efficiency in saving energy and protecting the environment by allowing 70×10^6 t/a of argillized ultrafine tailings slurry to be disposed safely and efficiently with a cost saving of more than 53×106 Yuan/a, which gives it great promise for use in domestic and foreign mines.

Treatment of Wastewater from Dairy Farm by Coagulation Sedimentation

In order to evaluate the processing efficiency of coagulation sedimentation on wastewater from dairy farm and to provide reference for wastewater treat- ment, an experimental study was carried out to investigate effects of coagulant dosage, types, pH, dosage of coagulant aids PAM on removal rate of COD, turbidity and SS in wastewater from dairy farm. The results showed that PAC displayed higher effectiveness in treatment; the removal rates of COD, turbidity and SS were 61.4%, 86.6% and 94.5% respectively when pH was 11.0, PAC dosage was 150 mg/L, and PAM dosage was 4 mg/L. The results indicated that coagulation sedimentation could reduce organic content of wastewater effectively and alleviate the load of subsequent biochemical treatment.

Effects on coagulation factor production following primary hepatomitogen-induced direct hyperplasia

AIM： To investigate the molecular mechanisms involved in coagulation factor expression and/or function during direct hyperplasia （DH）-mediated liver regeneration. METHODS： Direct hyperplasia-mediated liver regeneration was induced in female C57BL/6 mice by administering 1,4-bisr2-（3,5-dichloropyridyloxy）] benzene （TCPOBOP）, a representative hepatomitogen. Mice were weighed and sacrificed at various time points [Day 0 （D0： prior to injection）, 3 h, D1, D2, D3, and D10] after TCPOBOP administration to obtain liver and blood samples. Using the RNA samples extracted from the liver, a comprehensive analysis was performed on the hepatic gene expression profiling of coagulation-related factors by real-time RT-PCR （fibrinogen, prothrombin, factors Ⅴ, Ⅶ, Ⅷ, Ⅸ, Ⅹ, Ⅺ, Ⅻ, ⅩⅢβ , plasminogen, antithrombin, protein C, protein S, ADAMTS13, and VWF）. The corresponding plasma levels of coagulation factors （fibrinogen, prothrombin, factors Ⅴ, Ⅶ, Ⅷ, Ⅸ, Ⅹ, Ⅺ, Ⅻ, ⅩⅢ, and VWF） were also analyzed and compared with their mRNA levels. RESULTS： Gavage administration of TCPOBOP （3 mg/kg body weight） resulted in a marked and gradual increase in the weight of the mouse livers relative to the total body weight to 220% by D10 relative to the DO （control） ratios. At the peak of liver regeneration （D1 and D2）, the gene expression levels for most of the coagulationrelated factors （fibrinogen, prothrombin, factors Ⅴ, Ⅶ, Ⅷ, Ⅸ,Ⅺ, Ⅻ, ⅩⅢβ, plasminogen, antithrombin, protein C, ADAMTS13, VWF） were found to be downregulated in a time-dependent manner, and gradually recovered by D10 to the basal levels. Only mRNA levels of factor X and protein S failed to show any decrease during the regenerative phase. As for the plasma levels, 5 clotting factors （prothrombin, factors Ⅷ, Ⅸ, Ⅺ, and Ⅻ） demonstrated a significant decrease （P 〈 0.05） during the regeneration phase compared with DO. Among these 5 factors, factor Ⅸ and factor Ⅺ showed the most dramatic decline in their activities by about 50% at D2 compared to the basal levels, and these reductions in plasma activity for both factors were consistent with our RT-PCR findings. In contrast, the plasma activities of the other coagulation factors （fibrinogen, factors Ⅴ, Ⅶ, ⅩⅢ, and VWF） were not significantly reduced, despite the reduction in the liver mRNA levels. Unlike the other factors, FX showed a temporal increase in its plasma activity, with significant increases （P 〈 0.05） detected at DI. CONCLUSION： Investigating the coagulation cascade protein profiles during liver regeneration by DH may help to better understand the basic biology of the liver under normal and pathological conditions.

Effects of Coagulation and Ozonation Pretreatments on Biochemical Treatment of Fluid Catalytic Cracking Wastewater

Fluid catalytic cracking (FCC) salty wastewaters, containing quaternary ammonium compounds (QACs), are very difficult to treat by biochemical process. Anoxic/oxic (A/O) biochemical system, based on nitrification and denitrification reactions, was used to assess their possible biodegradation. Because of the negative effects of high salt concentration (3%), heavy metals and toxic organic matter on microorganisms’ activities, some techniques consisting of dilution, coagulation and flocculation, and ozonation pretreatments, were gradually tested to evaluate chemical oxygen demand (COD), ammonia-nitrogen (ammonia-N) and total nitrogen (TN) removal rates. In this process of FCC wastewater, starting with university-domesticated sludge, the ammonia-N and TN removal rates were worst. However, when using domesticated SBR’s sludge and operating with five-fold daily diluted influent (thus reducing salt concentration), the ammonia-N removal reached about 57% while the TN removal rate was less than 37% meaning an amelioration of the nitrification process. However, by reducing the dilution factors, these results were inflected after some days of operation, with ammonia-N removal decreasing and TN barely removed meaning a poor nitrification. Even by reducing heavy metals concentration with coagulation/flocculation process, the results never changed. Thereafter, by using ozonation pre-treatment to degrade the detected organic matter of di-tert-butylphenol and certain isoparaffins, COD, ammonia-N and TN removal rates reached 92%, 62% and 61%, respectively. These results showed that the activities of the microorganisms were increased, thus indicating a net denitrification and nitrification reactions improvement.

CHARACTERS OF SEDIMENTATION OF SUSPENSION FLOCCULATED OR COAGULATED

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Removal Effect of Coagulating Sedimentation Method on Polyethylene Microplastics in Water

Microplastic is a new kind of pollutant.It exists widely in the aquatic environment and seriously endangers the aquatic ecosystem.In this study,the coagulating sedimentation method was used to remove microplastics in water.Polyethylene(PE)was selected as the representative of microplastics,polyferric sulfate(PFS),polyaluminum chloride(PAC)and aluminum sulfate(AS)were used as coagulant,and polyacrylamide(PAM)was used as coagulant aid to study the effects of pH,coagulant concentration and sedimentation time on the removal of PE by single and composite coagulant.The results showed that when the dosage of PFS was 0.5 g/L and pH was 5.0,the removal rate could reach 82.14%,which was better than PAC and AS,indicating that PFS had better coagulation and sedimentation performance for PE;the composite coagulant of PFS+PAC+AS(1 g/L+0.2 g/L+0.2 g/L,pH was 5.0)had the highest removal rate of PE,reaching 96.06%;the removal rate of PE increased with the increase in sedimentation time,but considering that the longer sedimentation time has less contribution to the improvement of removal rate,it is recommended that 4 h is appropriate.

钙离子浓度对混凝沉淀-纳滤膜污染机制的影响研究

膜技术以高效、占地少和工艺洁净等优点在城市污水厂二级出水回用中广泛运用,膜污染问题是膜分离技术现阶段应用的研究重点与难点。该研究采用模拟城市污水厂二级出水作为原水,投加CaCl_(2)改变离子浓度,探究Ca^(2+)浓度对混凝沉淀-NF工艺膜污染的作用机制,通过膜污染模型、膜污染指数等方法对不同浓度条件下的膜污染过程进行分析,结合xDLVO理论在微观层面对膜污染过程中的界面作用机制进行定量分析。研究结果表明:当Ca^(2+)浓度为120 mg/L时,膜比通量降至最低点,膜污染可逆阻力和不可逆阻力均呈现最高值,相应地,此时的膜污染指数达到顶峰,膜表面滤饼层密实程度最高,这显著指示了膜污染程度的严重性。同时,在此浓度条件下,膜进水中污染物与NF膜之间的能量势垒,以及膜进水中污染物与膜表面已存在污染物之间的能量势垒均呈现最低值,这种能量势垒的降低进一步促进了膜污染的形成,使得污染过程在该浓度条件下更易发生。

Features and mechanism for coagulation－flocculation processes of polyaluminum chloride

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The diffusive fluxes of inorganic nitrogen across the intertidal sediment-water interface of the Changjiang Estuary in China

Ammonium and nitrate concentrations were analyzed in near-bottom water and pore water collected from ten stations of the intertidal flat of the Changjiang Estuary during April, July, November and February. The magnitudes of the benthic exchange fluxes were determined on the basis of concentration gradients of ammonium and nitrate at the near-bottom water and interstitial water interface in combination with calculations of a modified Fick＇ s first law. Ammonium fluxes varied from - 5.05 to 1.43 μg/（ cm^2·d） and were greatly regulated by the production of ammonium in surface sediments, while nitrate fluxes ranged from - 0. 38 to 1.36 μg/ （ cm^2·d） and were dominated by nitrate concentrations in the tidal water. It was found that ammonium was mainly released from sediments into water columns at most of stations whereas nitrate was mostly diffused from overlying waters to intertidal sediments. In total, 823.75 t/a ammonium-N was passed from intertidal sediments to water while about 521.90 t/a nitrate-N was removed from overlying waters to intertidal sediments. This suggests that intertidal sediments had the significant influence on modulating inorganic nitrogen in the tidal water.

Nanoparticle nucleation and coagulation in a mixing layer

Numerical simulation of nanoparticle nucleation and coagulation in a mixing layer with sulfuric acid vapor binary system is performed using the large eddy simulation and the direct quadrature method of moment. The distributions of number concentration, volume concentration, and average diameter of nanoparticles are obtained. The results show that the coherent structures have an important effect on the distributions of number concentration, volume concentration and average diameter of nanoparticles via continuously transporting and diffusing the nanoparticles to the area of low particle concentration. In the streamwise direction, the number concentration of nanoparticles decreases, while the volume concentration and the average diameter increase. The distributions of number concentration, volume concentration and average diameter of nanoparticles are spatially inhomogeneous. The characteristic time of nucleation is shorter than that of coagulation. The nucleation takes place more easily in the area of low temperature because where the number concentration of nanoparticles is high, while the intensity of coagulation is mainly affected by the number concentration. Both nucleation and coagulation result in the variation of average diameter of nanoparticles.

Simulation of the Brownian coagulation of nanoparticles with initial bimodal size distribution via moment method

The Brownian coagulation of nanoparticles with initial bimodal size distribution, i.e., mode i and j, is numerically studied using the moment method. Evolutions of particle number concentration, geometric average diameter and geometric standard deviation are given in the free molecular regime, the continuum regime, the free molecular regime and transition regime, the free molecular regime and continuum regime, respectively. The results show that, both in the free molecular regime and the continuum regime, the num- ber concentration of mode i and j decreases with increasing time. The evolutions of particle geometric average diameter with different initial size distribution are quite different. Both intra-modal and inter-modal coagulation finally make the polydispersed size distribution become monodispersed. As time goes by, the size distribution with initial bimodal turns to be unimoda/and shifts to a larger particle size range. In the free molecular regime and transition regime, the inter- modal coagulation becomes dominant when the number concentrations of mode i and j are of the same order. The effects of the number concentration of mode i and mode j on the evolution of geometric average diameter of mode j are negligible, while the effects of the number concentration of mode j on the evolution of geometric average diameter of mode j is distinct. In the free molecular regime and continuum regime, the higher the initial number concentration of mode j, the more obvious the variation of the number concentration of mode i.

物化预处理-生化组合工艺处理草甘膦生产废水工程实例

对不同工艺废水采用物化方法分质预处理后,利用厌氧-缺氧-CAST组合工艺处理综合废水,设计处理量为470 m^(3)/d。运行实践表明:中和反应-混凝沉淀对总磷的去除率可以达到46%,整个工艺处理出水COD稳定低于500 mg/L,总磷稳定低于8 mg/L,出水水质达到接管要求。

两级化学-混凝沉淀工艺处理高浓度含氟废水工程实例

针对某从事硅砂开采、加工、提纯企业排放的高浓度含氟废水,文中采用两级化学-混凝沉淀组合工艺,在投加钙盐的基础上联合投加适量PAC和PAM。工程实践结果表明,在系统稳定运行的情况下,出水可稳定满足回用及排放要求,回用水氟离子浓度小于20 mg/L,排水氟离子浓度小于10 mg/L,且联合药剂投加可提高氟化物的去除率。

UASB-两级A/O-混凝工艺处理生猪养殖污水工程实例

针对某规模生猪养殖场污水成分复杂、污染物浓度高、可生化性较好等水质特征,设计采用预处理-UASB-两级A/O-混凝沉淀-多介质过滤-消毒组合工艺进行处理,介绍了工艺流程及主要设计参数,考察并分析了组合工艺对生猪养殖污水的处理效果。工程运行结果表明,该工艺处理效率高,出水稳定,主要污染物指标均达到GB 8978—1996《污水综合排放标准》中的一级标准,出水可用于农田灌溉。

聚合氯化铝-聚丙烯酰胺处理含氟废水研究

使用聚合氯化铝(PAC)-聚丙烯酰胺(PAM)联合处理含氟废水,考察了PAC投加量、PAM浓度、pH值、反应时间以及搅拌速度对除氟效果的影响。结果表明,在PAC投加量4400 mg/L、PAM浓度1 mg/L、溶液pH值7.0、反应时间20 min、搅拌速度300 r/min时,氟去除率达97.98%,除氟后溶液中氟离子残余浓度为0.81 mg/L。溶液中杂质离子的存在会降低PAC的除氟性能。

混凝沉淀-Fenton氧化工艺处理有机化工生产废水研究

为减轻高浓度、难降解有机化工生产废水对环境保护造成的压力,研究依据某金属缓蚀剂在工业生产中的废水情况,采用混凝改进工艺来进行复合处理,并通过对混凝沉淀工艺和氧化工艺的设计配比和实验检验,旨在提高其降解能力。结果表明,联合工艺对废水处理下的污染物浓度降低效果明显,重铬酸盐指数的去除率达到了89.41%,且混合工艺处理下的生化需氧量比值达到0.47,分子降解效果远大于单一工艺处理效果。研究提出的复合处理工艺能高效处理甲基苯并三氮唑废水,为化工行业的健康发展和环境保护提供建设性技术手段。

IC厌氧-两级AO工艺处理白酒废水工程实例

针对白酒废水中有机物含量高、可生化性较好、色度高、悬浮物浓度高等特点,某企业设计采用IC厌氧-两级AO-深度处理组合工艺进行处理,工程运行结果表明,在综合废水进水ρ(COD_(Cr))≤11750 mg/L、ρ(BOD_(5))≤5875 mg/L、ρ(NH_(3)-N)≤60 mg/L,处理后出水ρ(COD_(Cr))≤30 mg/L、ρ(BOD_(5))≤6 mg/L、ρ(NH_(3)-N)≤1.5 mg/L,满足GB 3838—2002《地表水环境质量标准》中Ⅳ类标准要求,其他指标满足GB/T 18920—2020《城市污水再生利用城市杂用水水质》中城市绿化及道路清扫水质要求。

石灰沉淀-混凝沉淀处理含氟废水的试验

单纯的石灰沉淀法不能把高浓度含氟废水降到较低水平,Ca(OH)2+Al2(SO4)3(或PAC)是处理100mg/L左右的含氟废水的有效方法。其中,PAC的处理效果优于Al2(SO4)3,在pH值范围6.0～7.0时,PAC投加400mg/L的条件下,出水可达10mg/L以下,满足了回用及排放的要求。

混合染料化工废水的物化-生化联合处理工艺研究

用物化(混凝沉淀)-生化(SBR)工艺联合处理混合染料化工废水。结果表明,混合废水经过预处理、一级物化处理、SBR生化处理以及二级物化处理后,COD、NH3-N和色度去除率均达90%以上,最终出水各项指标均达到国家二级排放标准,证明物化-生化联合工艺是一种处理混合染料化工废水的有效途径。