Mechanism of effective nocardioform foam control measures for non-selector activated sludge systems.

Solids retention time (SRT), biological scum trapping and recycle, and the dynamic equilibrium between Nocardioform populations in the foam and the mixed liquor are the controlling factors in activated sludge foaming events caused by Nocardioform bacteria. For the operating modes described in this paper, a cured mixed liquor foaming condition (filament counts of approximately 10(5) intersections/g volatile suspended solids) was only achieved when SRT control, selective wasting, and polymer addition were in effect. Solids retention time control, with the SRT remaining below 1.5 days, and selective wasting will cure a severely foaming mixed liquor, but effects will only be observed after 3 or 4 months after implementation. The combined wastage of Nocardioform bacteria from selective wasting and SRT control can ensure long-term foam control to the operation of a pure-oxygen activated sludge system with foam-trapping features. An SRT of 0.3 days will result in the complete washout of Nocardioform bacteria from the activated sludge system, which can then operate at an SRT of 3 days free of Nocardioform. Polymer addition to mixed liquor is only effective for foam control when a large portion of the system biomass exists as a heavy layer of foam above the mixed liquor.     

活性污泥法处理过程中泡沫问题的产生与控制

活性污泥法运行过程中经常受泡沫问题的影响,导致处理效果的降低以及运行费用的提高.大量研究表明,污泥中某些丝状菌或放线菌的过度增殖是造成活性污泥工艺中泡沫问题的主要原因.讨论了活性污泥过程中泡沫的产生原因、已知的发泡微生物的种类、影响发泡的环境因素和过程参数及常用的泡沫控制技术,并对污泥消化过程中的泡沫问题作了简单的介绍.     

高稳定性污泥蛋白发泡剂的发泡特性及应用研究

以污泥蛋白为实验材料，通过加入不同量的稳定剂GP-1，配制成高稳定性污泥蛋白发泡剂，并对高稳定性污泥蛋白发泡剂的发泡特性和影响因素进行研究。结果表明，以污泥蛋白10 mL、水90 mL、GP-1 0.4 g配方组合为研究对象，所制备的泡沫初始体积为770 mL，泡沫泌水时间大于15 h，泡沫半衰期大于64 h，泡沫综合发泡能力为2.2×10⁶ mL·min，泡沫的最佳搅拌时间为5 min，泡沫的泌水时间和泡沫的半衰期都是随着温度的上升而下降，在pH为3～13时泡沫稳定。经过对高稳定性污泥蛋白发泡剂发泡特性研究以及对水泥的胶凝时间、特性进行比较，研制出污泥蛋白泡沫混凝土发泡剂，并制备污泥蛋白泡沫混凝土块；结果表明，当污泥蛋白泡沫混凝土发泡剂的用量分别为0、6、6.8、7.6、8.4和9.2 mL，水泥为200 g时，制备泡沫混凝土块，其密度由2.07 g/cm³下降到0.34 g/cm³，体积由130 cm³ 上升到755 cm³；在泡沫混凝土块脱模后的第1 d、第7 d、第28 d分别称量他们的重量变化情况，结果表明，泡沫混凝土块第1 d和第7 d无重量变化，第28 d的重量明显减轻。该研究为污泥蛋白研制成为泡沫混凝土发泡剂，并应用于屋面隔热、保温建立前期基础。     

Chemical recycling of poly(ethylene terephthalate) (pet) by hydrolysis and glycolysis

In this paper we review an interesting method of PET recycling, i.e. chemical recycling; it is based on the concept of depolymerizing the condensation polymer through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high-quality chemical products. In this work our attention is confined to the hydrolysis (neutral, acid and alkaline) and glycolysis processes of PET chemical recycling; operating conditions and mechanism of each method are reported and described. The neutral hydrolysis has an auto accelerating character; two kinetic models have been proposed: an half-order and a second order kinetic model. The acid hydrolysis could be explained by a modified shrinking core model under chemical reaction control and the alkaline hydrolysis by a first-order model with respect to hydroxide ion concentration. To describe glycolysis, two different kinetic models have been proposed where EG can act or not as internal catalyst. Further experimental and theoretical investigations are required to shed light on the promising processes of PET chemical recycling reviewed in this work.     

Much Ado: How Big Is the Problem of Hydrolysis of Methyl Tertiary Butyl Ether (MtBE) to Form Tertiary Butyl Alcohol (tBA)?

Groundwater contaminated by the gasoline additive methyl tertiary butyl ether (MtBE) is also frequently impacted by tertiary butyl alcohol (tBA). The USEPA recently sponsored a study that discusses the possibility of hydrolysis of MtBE to form tBA during analytical procedures. This finding is important because it suggests that existing tBA data may not accurately depict tBA or MtBE concentrations in groundwater. This article discusses the mechanism and kinetics of MtBE hydrolysis, then presents three case studies of analytical results from sites in California, USA. Although these case studies are limited in scope, the data do not support the occurrence of the hydrolysis of MtBE to form tBA due to acid preservation of groundwater samples. At a minimum, this suggests that MtBE hydrolysis may not be as pervasive a problem as suggested in USEPA's study; therefore, concerns about the validity of historical tBA data may not be warranted. The reason for this result may be simple: there are two necessary factors that promote hydrolysis: low pH and high temperature (above 40°C). Although the static headspace analysis method used to obtain the data in the White et al. study may require heating to achieve adequate sensitivity, many laboratories perform purge-and-trap analyses without heating. Under those conditions, hydrolysis may not occur. However, it may be prudent to preserve samples with alkaline preservatives, to eschew high temperatures during the analysis of groundwater samples, or to neutralize the sample pH before heating.     

焦化废水泡沫分离液的Fenton催化氧化预处理

以焦化废水处理过程产生的泡沫分离液为研究对象，对其进行Fenton催化氧化处理实验，考察H₂O₂用量、Fe²⁺浓度、pH和反应时间4个因素对处理效果的影响，并结合GC/MS方法比较处理前后泡沫分离液中有机物的种类及其生物降解性的变化。结果表明，采用［H₂O₂］=100 mmol/L、［Fe²⁺］=100 mg/L、pH=3、反应时间为30 min的Fenton催化氧化反应条件，可以使分离液的COD去除率达到68%以上；经Fenton处理后，分离液的B/C值由0.12提高至0.38，生物降解性明显改善；通过GC/MS的分析，基本明确分离液中含有的有机物主要为酚、胺、腈、酯类有机物及喹啉、吡啶等杂环化合物，大多数属于难降解且生物毒性较强的有机物。针对这些复杂组分共存的泡沫分离液，利用Fenton试剂较强的氧化能力能够将其含有的有毒/难降解有机物转化为低毒或无毒的小分子有机物，为其后续的生物处理创造良好的条件。     

Determination of chemical warfare agents in soil and material samples

A gas Chromatographic method for the determination of phenylarsenic compounds (sternutators) and their metabolites in soil and material samples is described. The chemical warfare agents (CWA), but not their hydrolysis and oxidation products, can be detected with GC/ECD. After derivatization with thiols or dithiols, the sum of diphenylarsenic and phenylarsenic compounds can be determined with GC/ECD. The comparison of the analytical results with and without derivatization shows that the sternutators in the investigated samples are metabolized in part.     

不同稳定剂对污泥蛋白发泡特性的影响研究

污泥含有蛋白质,经过高温水解可产生水解蛋白液(简称污泥蛋白),该蛋白具有发泡特性,经通风搅拌可产生泡沫;由于污泥蛋白所产生的泡沫具有不稳定、易破裂的特点,因此,设计了不同稳定剂对污泥蛋白发泡特性的影响研究实验,解决污泥蛋白所产生泡沫的稳定性问题。结果表明,在测定污泥蛋白的基本发泡特性实验中,10 mL污泥蛋白稀释10倍时,初始泡沫量较大,达到2 153 mL,但泡沫半衰期相对较短,时间为27 min;在10 mL污泥蛋白中分别加入0.2 g十六烷基三甲基溴化氨(CTAB)、羧甲基纤维素钠(CMC)、GP-1,并用水稀释10倍,制成泡沫后的初始泡沫量分别为1 380、1 400和1 248 mL,相对降低了773、753和905 mL;泡沫半衰期分别为31、76和509 min,相对提高了4、49和482 min,尤其是GP-1作为稳定剂时,泡沫的半衰期与不加稳定剂时相比提高了15倍;在10 mL污泥蛋白中加入0.2 g十六烷基三甲基溴化氨与0.2 g GP-1的复配稳定剂,用水稀释10倍,制成泡沫后的初始泡沫量为1 525 mL,相对降低了628 mL;泡沫半衰期为95 min,相对提高了68 min。因此,GP-1是污泥蛋白最好的泡沫稳定剂。     

Influence of ultrasonication on anaerobic bioconversion of sludge.

The influence of ultrasonication on hydrolysis, acidogenesis, and methanogenesis in anaerobic decomposition of sludge was investigated. The sonicated sludge exhibited prehydrolysis and preacidogenesis effects in the anaerobic decomposition process. First-order hydrolysis rates increased from 0.0384 day(-1) in the control digester to 0.0672 day(-1) in the digester fed, with sludge sonicated at 0.52 W/mL. The sonication appeared to be ineffective in relation to acidogenesis reaction rates, but it provided a better buffering capacity to diminish the adverse effect of acidification. Digesters fed with sonicated sludge demonstrated enhanced methanogenesis over the control unit. Determination by coenzyme F420 verified that sonication is able to promote the growth of methanogenic biomass and facilitate a positive methanogenic microbial development in suppressing the initial methanogenesis limitation. The results suggest that ultrasonication could enhance anaerobic decomposition of sludge, resulting in an accelerated bioconversion, improved organics degradation, improved biogas production, and increased methane content.     

粉煤灰资源化的一种有效途径

本文对影响粉煤灰泡沫玻璃质量的主要因素:玻璃软化温度与发泡剂的选择、发泡温度与发泡时间、发泡剂生成气体的温度、坯体成型压力等关键问题进行了探索,这些问题的探索对提高粉煤灰泡沫玻璃质量,获得性能优良的粉煤灰泡沫玻璃具有十分重要的意义。     

内循环泡沫浮选塔间歇分离含镉废水

为强化气液传质,提出了泡沫塔对泡沫分离性能影响的研究,并为此设计了在泡沫塔内加内循环套筒的泡沫分离塔。结果表明,与没有加内循环套管的常规塔相比,通过FT-IR检测分析,内循环塔性能明显优于常规塔。在间歇分离条件下,研究在内循环塔内处理含镉废水,探讨pH、LAS、停留时间、气泡大小等因素对镉去除率的影响。确定最佳处理条件为:pH=4.0,LAS=65 mg/L,塔内停留时间大于20 min,气体流量为250 mL/min,在此最佳实验条件下,镉的去除率可达99.9%以上,此时的镉质量浓度为10 mg/L。表面活性剂协同效应实验结果表明,在加入阳离子表面活性剂十二烷基二甲基苄基溴化铵时,会形成一个二元表面活性剂协同效应区。     

Catalytic hydrolysis of urea from wastewater using different aluminas by a fixed bed reactor

In order to find an effective method for treating urea wastewater, the experiments on the hydrolysis of urea in wastewater were conducted in a fixed bed reactor with different aluminas (α-Al₂O₃, γ-Al₂O₃, and η-Al₂O₃) as catalysts respectively in contrast with inert ceramic particle. The results indicate that the three alumina catalysts show obvious catalytic activity for urea hydrolysis at 125 °C. The order of activity is η-Al₂O₃?>?γ-Al₂O₃?>?α-Al₂O₃, and the activity difference increases with increasing temperature. According to the characterization results, surface acidity has little impact on the activity of catalyst. However, it was found that surface basicity of alumina catalyst plays an important role in catalytic hydrolysis of urea, and the activity of catalyst may be also influenced by the basic strength. With η-Al₂O₃ as catalyst, the urea concentration in wastewater is reduced to 4.96 mg/L at a temperature of 165 °C. Moreover, the η-Al₂O₃ shows a good stability for urea hydrolysis. The hydrolysis of urea over η-Al₂O₃ catalyst can evidently reduce the reaction temperature and is promising to replace industrial thermal hydrolysis process.     

印染废水水解酸化处理中填料式反应器与UASB反应器的比较

根据印染废水的特点和印染废水处理工程实例，从适用性、与其他工艺的衔接、工程造价、运行费用及水解效果等方面对UASB水解酸化反应器和填料式水解酸化反应器进行比较研究。研究表明，UASB水解酸化反应器在适用性和工程造价两个方面具有一定的缺陷；但是UASB水解酸化反应器对印染废水中COD、SS和色度去除率能够分别达到50％、73％和75％，明显高于填料式水解酸化反应器；且UASB水解酸化反应器每降解1kgCOD所需电量为（0．23±0．05）kW·h，优于填料式水解酸化反应器。     

Improvement of thermal hydrolysis rate of dichloroacetic acid using alcohol

Dichloroacetic acid (DCAA) is produced during the oxidation of trichloroethylene. It is also produced in drinking water treatment as a disinfection by-product. DCAA is a problem material, because of its toxicity. The objective of this research is to find the final products and the reaction pathway of the DCAA decomposition by hydrolysis, and to increase the hydrolysis rate. The removal of both chlorine atoms in DCAA structure was achieved with hydrolysis at around 75 degrees C, and the final products were oxalic acid and glycolic acid. The reaction pathway was the production of oxalic acid and glycolic acid from two glyoxylic acid molecules by Cannizzaro reaction after the glyoxylic acid production from dechlorination of DCAA with hydrolysis. The hydrolysis rate of DCAA was increased with the use of 90% ethanol solution as solvent. The activation energy of DCAA was about 80 kJ/mol in it, while it was around 105 kJ/mol in water.     

利用废CRT屏玻璃为原料制备泡沫玻璃

以废阴极射线管(CRT)屏玻璃为主要原料,碳黑为起泡剂,采用粉末烧结法制备了低密度保温泡沫玻璃。通过扫描电镜(SEM)、导热系数测定仪等分析手段,研究了起泡剂的用量、发泡温度和发泡时间对泡沫玻璃泡径、密度、热学性能以及机械力学性能的影响。结果表明,在相同烧制工艺条件下,随起泡剂掺加量增加,烧制所得的泡沫玻璃密度成"V"型变化;当其掺加量为0.20%时,泡沫玻璃在密度、孔径分布以及力学性能上均达到最佳。随着发泡温度的提高和发泡时间的延长,密度会逐渐减小,泡沫玻璃的气泡会逐渐增大,以致产生连通现象。当发泡温度为820℃、发泡时间为30min时烧制的泡沫玻璃密度为0.180 g/cm3,导热系数为0.0695 W/(m.K)。     

印染废水水解酸化处理中填料式反应器与UASB反应器的比较

根据印染废水的特点和印染废水处理工程实例,从适用性、与其他工艺的衔接、工程造价、运行费用及水解效果等方面对UASB水解酸化反应器和填料式水解酸化反应器进行比较研究。研究表明,UASB水解酸化反应器在适用性和工程造价两个方面具有一定的缺陷;但是UASB水解酸化反应器对印染废水中COD、SS和色度去除率能够分别达到50%、73%和75%,明显高于填料式水解酸化反应器;且UASB水解酸化反应器每降解1 kg COD所需电量为(0.23±0.05)kW·h,优于填料式水解酸化反应器。     

Degradation of polydimethylsiloxane fluids in the environment--a review

Due to their insolubility in water and high adsorption coefficient, liquid polydimethylsiloxanes (PDMS) discharged as effluent will adsorb to particulate matter and, therefore, will become a component of sewage sludge during waste water treatment. The subsequent environmental fate of PDMS will depend on the fate of the sludge. Due to increasing practices of soil amendment with sewage sludge the principal environmental compartment receiving PDMS fluids is the soil. Degradation of PDMS is a common process taking place in many different types of soils. It occurs through a unique combination of environmental degradation processes. Initial hydrolysis of PDMS is catalysed by clay minerals, the principal component of soil. The primary hydrolysis product, dimethylsilanediol (DMSD), is then either biodegraded, or evaporated into the atmosphere, where it is subsequently oxidised in the presence of sunlight. The end products in both cases are expected to be CO2, SiO2 and H2O.     

Alkaline hydrolysis of humic substances--spectroscopic and chromatographic investigations.

To find out more on the structure of humic substances (HS), isolated dissolved organic carbon (DOC) samples from a brown water lake and a wastewater effluent were fractionated and subjected to alkaline hydrolysis. UV/Vis and fluorescence spectroscopy, as well as size-exclusion chromatography with on-line detection of UV absorption, fluorescence and DOC concentration were used to investigate the structural changes caused by the hydrolysis reaction. Following hydrolysis, the fluorescence intensity increased considerably despite a decrease in the UV absorption. The UV absorption and the DOC data from the SEC experiments revealed a strong shift to smaller molecular sizes after hydrolysis. The spectra of the hydrolysed samples, as well as the size-exclusion chromatograms, were compared to spectra of hydroxybenzoic acids and hydroxycinnamic acids. From this comparison, it can be concluded that the hydrolysis products have a structure similar to these organic acids.     

Degradation of tetraphenylphosphonium bromide at high pH and its effect on radionuclide solubility

Recently, tetraphenylphosphonium bromide (TPPB) has been used to remove technetium from some radioactive waste streams. However, before TPPB could be approved for use it was necessary to show that TPPB and its degradation products would not have a significant detrimental effect on post-closure performance of a radioactive waste repository. TPPB is known to be stable at neutral pH, however, under alkaline conditions it degrades by an alkaline hydrolysis mechanism to triphenylphosphonium oxide (TPPO). Degradation can also occur by radiolysis to produce triphenylphosphine (TPP). The kinetics of the alkaline hydrolysis degradation of TPPB is described and the solubility of europium, iodine, nickel, technetium(VII) and uranium(VI) in aqueous solutions of TPPB and its degradation products is reported. These results were used to support the use of TPPB in removing technetium from some waste streams.     

Solvent and surfactant enhanced solubilization, stabilization, and degradation of amitraz

In an effort to help with the development of effective dip vat management and waste disposal strategies this study determined how solution properties such as pH, buffer composition, ionic strength, temperature, solubility in organic solvents and the addition of commonly used solubilizing agents influenced the hydrolysis of amitraz. Amitraz degrade by means of hydrolysis described by a pseudo-first order rate process and a type ABCD pH rate profile. Hydrolysis increased with temperature and was fastest at low pH, slowest at neutral to slightly alkaline pH, and slightly increased above pH 10. However, buffer concentration and ionic strength influenced the hydrolysis rate and had to be accounted for before constructing a pH rate profile. Hydrolysis seems to depend on the dielectric constant of solvent mixtures and was fastest in water, slower in propylene glycol and ethanol solutions, and slowest in DMSO mixtures. In surfactant solutions, anionic micelles enhanced and cationic micelles retarded the hydrolysis rate. The magnitude of micellar effects decreased with increasing concentrations of the surfactants. The increased solubility and faster hydrolysis of amitraz in the sodium lauryl sulfate solutions showed that anionic surfactants potentially could be used for cleaning up amitraz spills, because it both solubilized the drug and catalyzed hydrolysis.