复合絮凝剂的去浊协同效应机理研究

用硅藻土自配水样,对几种有机和无机絮凝剂进行了单独和复配混凝实验,比较浊度去除效果,并用正交实验对有机和无机絮凝剂进行配伍,寻求不同投药顺序下的最佳组合.     

微生物絮凝剂对含藻微污染水的除浊性能研究

采用微生物絮凝剂JMBF-25和无机絮凝剂复合使用的方法,对含藻微污染水进行处理。结果表明,絮凝剂复合使用降低了无机絮凝剂的使用量,减轻了无机絮凝剂对环境的二次污染。处理含藻微污染水的最佳复配比为ρ(PAC) ρ(JMBF-25)=15mg／L 1．2mg／L或ρ(PFS) ρ(JMBF-25)=8mg／L 2．0mg／L。机理分析表明,絮凝剂JMBF-25絮凝机理以吸附架桥为主。     

聚二甲基二烯丙基氯化铵-聚合硫酸铁复合絮凝剂对污泥的脱水性能

研究了聚二甲基二烯丙基氯化铵-聚合硫酸铁复合絮凝剂(PDMDAAC-PFS)对活性污泥的脱水性能,考察了投加量、配比和PDMDAAC的特性粘数等对污泥比阻降低和滤液浊度与COD去除的影响,并与PFS、PDMDAAC、PFS与PD-MDAAC联用(分开加入)、聚丙烯酰胺(PAM)、阳离子型聚丙烯酰胺(CPF130)和KHYC型絮凝剂的脱水效果进行了比较.结果表明,PDMDAAC-PFS对污泥比阻的降低和滤液浊度与COD的去除效果最好,但产生絮团的大小和强度比CPF130差,而其中PDMDAAC和PFS的用量分别比单独使用PDMDAAC和PFS减少了一半以上;PDMDAAC与PFS复配,增加了絮凝剂分子聚集体体积,利于在污泥粒子群间吸附架桥.     

曝气＋化学絮凝法预处理环氧丙烷废水

根据环氧丙烷废水的特点，应用电化学法处理具有较高的可行性。运用电化学法处理PO废水前必须进行废水预处理，用以提高电流效率和延长极板寿命。采用曝气和化学絮凝结合的方法去除PO废水中的Ca2＋，同时去除部分COD。对曝气、无机絮凝剂（PACl、PFS）和有机絮凝剂（PAM）对PO废水处理过程中的曝气量、曝气时间、投药量、复配和沉降时间等主要影响因子进行了实验研究，通过比较Ca2＋、COD的去除效果、絮凝剂用量、沉降时间、处理成本等方面，在设定的实验参数下得到最佳预处理方案为：曝气量为2．5L／min，曝气45min，投加Na2CO3粉末24kg／t废水，充分混匀后加入PFS＋PAM复配絮凝剂。本方案具有废水处理效果好（Ca2＋的去除率为77．03％，COD的去除率为37．46％）、投药量少（（100＋7．5）g／t废水）、沉降时间短（5min）、处理成本低（0．675元／t废水）等优点。通过对比经预处理和不经预处理后电化学法对COD去除效果、电流和处理后阴极表面，验证了预处理方案的必要性与可行性。     

曝气+化学絮凝法预处理环氧丙烷废水简

根据环氧丙烷废水的特点，应用电化学法处理具有较高的可行性。运用电化学法处理PO废水前必须进行废水预处理，用以提高电流效率和延长极板寿命。采用曝气和化学絮凝结合的方法去除PO废水中的Ca²⁺，同时去除部分COD。对曝气、无机絮凝剂（PACl、PFS）和有机絮凝剂（PAM）对PO废水处理过程中的曝气量、曝气时间、投药量、复配和沉降时间等主要影响因子进行了实验研究，通过比较Ca²⁺、COD的去除效果、絮凝剂用量、沉降时间、处理成本等方面，在设定的实验参数下得到最佳预处理方案为：曝气量为2.5 L/min，曝气45 min，投加Na₂CO₃粉末24 kg/t 废水，充分混匀后加入PFS+PAM复配絮凝剂。本方案具有废水处理效果好（Ca²⁺的去除率为77.03%，COD的去除率为37.46%）、投药量少（（100+7.5）g/t废水）、沉降时间短（5 min）、处理成本低（0.675元/t废水）等优点。通过对比经预处理和不经预处理后电化学法对COD去除效果、电流和处理后阴极表面，验证了预处理方案的必要性与可行性。     

聚二甲基二烯丙基氯化铵-聚合硫酸铁复合絮凝剂对污泥的脱水性能

研究了聚二甲基二烯丙基氯化铵．聚合硫酸铁复合絮凝剂（PDMDAAC-PFS）对活性污泥的脱水性能，考察了投加量、配比和PDMDAAC的特性粘数等对污泥比阻降低和滤液浊度与COD去除的影响，并与PFS、PDMDAAC、PFS与PD-MDAAC联用（分开加入）、聚丙烯酰胺（PAM）、阳离子型聚丙烯酰胺（CPF130）和KHYC型絮凝剂的脱水效果进行了比较。结果表明，PDMDAAC-PFS对污泥比阻的降低和滤液浊度与COD的去除效果最好，但产生絮团的大小和强度比CPF130差，而其中PDMDAAC和PFS的用量分别比单独使用PDMDAAC和PFS减少了一半以上；PDMDAAC与PFS复配，增加了絮凝剂分子聚集体体积，利于在污泥粒子群间吸附架桥。     

Box-Behnken响应曲面法优化高聚复配絮凝剂制备条件

利用活性硅酸和聚合硫酸铁制备聚合硅酸硫酸铁,再采用二甲基二烯丙基氯化铵对其进行复配改性制备高聚复配絮凝剂。在单因素实验的基础上,以絮凝剂脱As性能为评价指标,采用Box-Behnken响应曲面法考察了Fe∶Si、改性剂量、改性温度对高聚复配絮凝剂制备的单独作用及交互影响作用,并建立了剩余c(As)的数学模型。结果显示,自变量对响应值的影响次序为:Fe∶Si改性温度改性剂量,改性剂量与改性温度及改性剂量与Fe∶Si交互影响显著;数学模型拟合度程度良好,模型显著,模型预测处理后最佳剩余c(As)=18.82μg/L,最佳工艺条件为Fe∶Si=2.1∶1,改性温度=79℃,改性剂量=0.56%(PFSS溶液质量),验证实验结果为剩余c(As)=19.21μg/L,预测值与测定值偏差率为2.07%。     

复合型絮凝剂处理景观水体

利用以生物絮凝剂(1 g/L MBF-28)与化学絮凝剂(5 g/L PAC)复配后的复合絮凝剂CBF28C处理景观水体,考虑了复配比、投加量、pH和投加顺序对处理景观水的影响。实验结果表明:对于反应体系为100 mL景观水体,当MBF-28与PAC溶液复配体积比为3∶1,反应体系pH为7.0,1 mL 1%CaCl2作助凝剂,1.5 mL CBF28C时,其絮凝效果最好,其COD,色度,TN,TP的去除率分别为90.7%,54.1%、46.6%和51.5%。最佳水力条件为:快速320 r/min,快搅时间45 s,慢速80 r/min,慢搅时间100 s。并且得出了前10 min内絮凝率的反应关系方程式。     

絮凝剂的开发进展

分别对无机高分子絮凝剂、有机高分子絮凝剂、微生物絮凝剂和废物回收制备絮凝剂的物性、应用状况进行了简要介绍，并列出了近年来大量研究人员对这儿类絮凝剂的研究成果和开发进展。     

微生物絮凝剂与聚合氯化铝复配处理涂料废水的响应面优化

采用响应面分析法对聚合氯化铝(PAC)与污泥生产的微生物絮凝剂复配处理涂料废水的过程进行了优化,设定的响应值为COD和色度去除率。实验分别拟合了关于COD去除率和色度去除率的二次模型,根据响应值的分布情况,确定涂料废水的最佳絮凝条件为微生物絮凝剂浓度47 mg/L,PAC浓度39 mg/L,pH为8.2,CaCl2浓度0.38 g/L,搅拌速度210 r/min。最佳絮凝条件下,微生物絮凝剂对涂料废水中COD和色度的去除率分别达到77.6%和68.9%。     

Chlorpyrifos acute exposure induces hyperglycemia and hyperlipidemia in rats

In this study we evaluated the hyperglycemic and hyperlipidemic effects of chlorpyrifos (CPF) after an acute exposure in rats. The mechanisms involved in hyperglycemia induced by CPF were studied. A single dose of CPF (50 mg kg⁻¹, subcutaneous, s.c.) was administered to overnight-fasted rats. Glucose and corticosterone levels, lipid status and paraoxonase (PON1) activity were determined in plasma of rats. Cardiovascular risk factors and the atherogenic index were calculated. Glycogen levels, tyrosine aminotransferase (TAT) and glucose-6-phosphatase (G6Pase) activities were determined in livers of rats. Cerebral acetylcholinesterase (AChE) activity was also determined. CPF caused an increase in glucose and glycogen levels as well as in TAT and G6Pase activities. The CPF exposure caused an increase in corticosterone levels, an inhibition of AChE activity and a reduction of PON1 activity. Regarding the lipid status, CPF induced an increase in triglycerides (TG) and low-density lipoprotein-cholesterol (LDL) levels and a decrease in high-density lipoprotein (HDL) levels associated with an increase of cardiovascular risk factors and the atherogenic index. The present study demonstrated that a single CPF administration caused hyperglycemia and hyperlipidemia in rats. The activation of the gluconeogenesis pathway, probably elicited by hypercorticosteronemia, is involved in the hyperglycemic effect of CPF in rats.     

Mother gestational exposure to organophosphorus pesticide induces neuron and glia loss in daughter adult brain

Chlorpyrifos (CPF) is a widely used organophosphorus pesticide with developmental neurotoxicity such as morphogenesis toxicity. In the present study, we assessed the effects of prenatal CPF exposure on systemic parameters and cytoarchitecture of medial prefrontal cortex (mPFC) in adulthood. Gestational dams were exposed to 5mg/kg/d of CPF during gestational days 13–17, while body weight, organ coefficient, and neuron and glia counts of offspring were determined on postnatal day 60. Our results showed that CPF treatment induced little or no effects on body weight and organ coefficients. There were also no significant pathological changes in mPFC. However, neuron and glia count analysis showed that CPF treatment reduced neuron and glia counts in anterior cingulate, prelimbic, and infralimbic areas of mPFC. The CPF react pattern was similar in both sexes, and there was no statistical difference in most of the sub-regions. Thus, our results revealed an embryonic origin brain deficit induced by gestational mother pesticide exposure.     

Effect of pulse frequency and interval on the toxicity of chlorpyrifos to Daphnia magna.

Due to the episodic nature in which organisms are exposed to non-point source pollutants, it is necessary to understand how they are affected by pulsed concentrations of contaminants. This is essential, as standard toxicity tests may not adequately simulate exposure scenarios for short-lived hydrophobic compounds, such as chlorpyrifos (CPF), a broad-spectrum organophosphate insecticide. Studies were conducted with 7-day old Daphnia magna for 7 days to evaluate the effect of pulse frequency and interval among multiple CPF exposures. Daphnids were exposed to a total exposure of either 12 h at 0.5 microg/l or 6 h at 1.0 microg/l nominal CPF, respectively, in all studies. For interval studies, D. magna were exposed to two pulses of CPF at each concentration, with 0-96-h intervals between pulses. For frequency studies, D. magna were exposed to each CPF concentration altering the pulse scheme by decreasing the exposure duration but increasing the number of pulses, keeping the total exposure time the same. The pulse interval between multiple pulses in these experiments was 24 h. Our results suggest that D. magna can withstand an acutely lethal CPF exposure provided that there is adequate time for recovery between exposures.     

Histopathological changes and antioxidant response in brain and kidney of common carp exposed to atrazine and chlorpyrifos

We investigated oxidative stress response and histopathological changes in the brain and kidney of the common carp after a 40-d exposure to CPF and ATR, alone or in combination, and a 20-d recovery. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) content were measured using standard assays. Our results indicated that exposure to ATR, CPF or a combination of the two for 40 d induced significant changes in antioxidant enzyme (SOD, CAT and GSH-Px) activities and MDA content in the brain and kidney of the common carp. Pathological changes included tissue damage that was more severe with increased of exposure dose. To our knowledge, this is the first report to study oxidative stress and histopathological effects caused by subchronic exposure to ATR, CPF and ATR/CPF combination on common carp. The information presented in this study may be helpful to understanding the mechanisms of ATR-, CPF- and ATR/CPF combination-induced oxidative stress in fish.     

Impact of chronic exposure to low doses of chlorpyrifos on the intestinal microbiota in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) and in the rat

The impact of the insecticide chlorpyrifos (CPF) on the mammalian digestive system has been poorly described. The present study aimed at evaluating the effect of chronic, low-dose exposure to CPF on the composition of the gut microbiota in a Simulator of the Human Intestinal Microbial Ecosystem: the SHIME® and in rats. The SHIME® comprises six reactor vessels (stomach to colon). The colonic segments were inoculated with feces from healthy humans. Then, the simulator was exposed to a daily dose of 1 mg of CPF for 30 days. The changes over time in the populations of bacteria were examined at different time points: prior to pesticide exposure (as a control) and after exposure. In parallel, pregnant rats were gavaged daily with 1 mg/kg of CPF (or vehicle) until the pups were weaned. Next, the rats were gavaged with same dose of CPF until 60 days of age (adulthood). Then, samples of different parts of the digestive tract were collected under sterile conditions for microbiological assessment. Chronic, low-dose exposure to CPF in the SHIME® and in the rat was found to induce dysbiosis in the microbial community with, in particular, proliferation of subpopulations of some strains and a decrease in the numbers of others bacteria. In compliance with European guidelines, the use of the SHIME® in vitro tool would help to (1) elucidate the final health effect of toxic agents and (2) minimize (though not fully replace) animal testing. Indeed, certain parameters would still have to be studied further in vivo.     

Chronic exposure to chlorpyrifos reveals two modes of action in the springtail Folsomia candida

Organophosphates are popular insecticides, but relatively little is known about their chronic effects on ecologically relevant endpoints. In this paper, we examine a life-cycle experiment with the springtail Folsomia candida, exposed via food to chlorpyrifos (CPF). The results for all endpoints (survival, growth and reproduction) were analyzed using the DEBtox model. Growth was unaffected by CPF, even at concentrations causing severe effects on survival and reproduction. Model analysis suggests that CPF directly affects the process of egg production. For the short-term response (45 days), this single mode of action accurately agreed with the data. However, the full data set (120 days) revealed a dose-related decrease in reproduction at low concentrations after prolonged exposure, not covered by the same mechanism. It appears that CPF interacts with senescence by increasing oxidative damage. This assumption fits the data well, but has little consequences for the predicted response at the population level.     

Conductive-diamond electrochemical oxidation of chlorpyrifos in wastewater and identification of its main degradation products by LC-TOFMS

The electrochemical transformation of the organophosphorous insecticide chlorpyrifos (CPF) was investigated in wastewater. The oxidation of CPF was carried out in a single-compartment electrochemical flow cell working under batch operation mode, using diamond-based material as anode and stainless steel as cathode. In order to evaluate its persistence and degradation pathway, two different concentration levels (1.0 mg L⁻¹ and 0.1 mg L⁻¹) were studied. Liquid chromatography/mass spectrometry was used for evaluation of the initial and electrolyzed solutions. The identification of CPF transformation products was performed by liquid chromatography-time of flight-mass spectrometry (LC-TOFMS). Results showed that CPF is completely removed at the end of treatment time. Analysis by LC-TOFMS allowed the identification of six degradation products (with Mw 154, 170, 197, 305 321 and 333). Three of the identified intermediates (Mw 170, 305 and 321) were completely removed at the end of electrolysis time. Interestingly, the formation of diethyl 3,5,6-trichloropyridin-2yl phosphate (chlorpyrifos oxon) and 3,5,6-trichloropyridin-2-ol was also found in previous reported degradation pathways using different degradation technologies.     

Diphenyl diselenide attenuates hepatic and hematologic toxicity induced by chlorpyrifos acute exposure in rats

Purpose

In this study, we investigated the effect of diphenyl diselenide [(PhSe)₂] on chlorpyrifos (CPF)-induced hepatic and hematologic toxicity in rats.

Methods

Rats were pre-treated with (PhSe)₂ (5?mg/kg) via the oral route (oral gavage) once a day for 7?days. On the eighth and ninth days, rats were treated with (PhSe)₂ (5?mg/kg) 30?min prior to CPF (50?mg/kg, by subcutaneous route). The aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase activities were determined in plasma of rats. Lipid peroxidation, protein carbonyl, and non-protein thiol levels as well as catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and gluthatione S-transferase activities were determined in livers of rats. Hematological parameters were also determined.

Results

The results showed that CPF caused hepatic oxidative damage, as demonstrated by an increase in lipid peroxidation and protein carbonyl levels which was associated with a decrease in antioxidant defenses. CPF exposure caused a reduction in the leukocyte, indicating hematologic toxicity. (PhSe)₂ was effective in attenuating these toxic effects caused by CPF exposure in rats.

Conclusions

The results indicated that (PhSe)₂ was effective in protecting the hepatic and hematologic toxicity induced by acute CPF exposure in rats.     

The use of conditional probability functions and potential source contribution functions to identify source regions and advection pathways of hydrocarbon emissions in Houston,Texas

In this study, we demonstrate the utility of conditional probability functions (CPFs), potential source contribution functions (PSCFs), and hierarchical clustering analysis (HAC) to identify the source region and transport pathways of hydrocarbons measured at five photochemical assessment monitoring stations (PAMS) near the Houston Ship Channel from June to October 2003. In contrast to scatter plots, which only show the pair-wise correlation of species, commonality in CPF figures shows both correlation and information on the source region of the species in question. In this study, we use over 50 hourly volatile organic compound (VOC) concentrations and surface wind observations to show that VOCs with similar CPF patterns likely have common transport pathways. This was established with the multivariate technique, which uses the hierarchical clustering analysis to define clusters of VOCs having similar CPF patterns. This method revealed that alkenes, and in particular those with geometric isomers such as cis-/trans-2-butene and cis-/trans-2-pentene, have similar CPF patterns and hence, a common area of origin. The alkane isomers often show CPF patterns among themselves, and similarly, aromatic compounds often show similar patterns. We also show how calculated trajectory information can be used in the PSCF analysis to produce a graphic picture that identifies specific geographic areas associated with a given VOC (or other pollutant). The use of these techniques in the chemically and meteorologically complex environment of Houston, Texas, suggests its further utility in other areas with relatively simpler conditions.