两种消解法测定沉积物总磷的对比

通过过硫酸钾消解法与HClO₄-H₂SO₄消解法对土壤和水系沉积物的标准物质,以及三峡水库沉积物未知样品中的总磷含量进行测定,并对检测结果进行对比,分析过硫酸钾消解法测定沉积物总磷的可行性。结果表明,在标准样品中,HClO₄-H₂SO₄消解法的检测结果是标准值的83%~100%,并且所有结果均在其不确定度范围之内;过硫酸钾消解法的检测结果仅达到标准值的19%~42%,超出其不确定度范围,不能作为有效数据。在未知样品中,过硫酸钾消解法检测结果也远低于HClO₄-H₂SO₄消解法检测结果,只达到后者的32%~52%。由此可见,过硫酸钾消解法测定沉积物或土壤中总磷,仍需要进一步的研究,以达到符合实际的检测结果。     

水质总氮测定影响因素分析

总氮是水质监测特别是湖库水质的重要指标之一,应用碱性过硫酸钾消解紫外分光光度法测定总氮时,空白校正吸光度不易控制,主要考虑药剂与消解时间,要选择合乎标准要求的过硫酸钾,必要时加以重结晶提纯,且碱性过硫酸钾溶液宜现用现配。消解时间不足,难以完全消解所有的过硫酸钾,应保证在达到规定的温度与压力后,消解时间保持在40min以上。     

碱性过硫酸钾消解测定城市污泥中总氮

城市污水处理厂污泥经风干粉碎后，用碱性过硫酸钾溶液在高压器皿中于124℃消解，取上清液以紫外分光光度法测定总氮。对11个污泥样品测定，相对标准差≤1．5％精密度较好。并用L-谷氨酸标准物加入11个溶液样品中作回收试验，回收率在94％～107％之间，准确度亦较好。     

硫酸——高锰酸钾冷消解法处理水中汞的探讨

目前测汞常用的消解方法是硫酸—高锰酸钾热消解法及高锰酸钾—过硫酸钾消解法。硫酸—高锰酸钾热消解法需在电热板上加热近沸30min(或在电炉上煮沸10min,严防瀑沸),高锰酸钾—过硫酸钾法也较麻烦。本文提出一种简单又省电的消解方法,即硫酸—高锰酸钾冷消解法,此法不需加热,在大批水样的分析中,更具有实际意义。     

水中总氮测定方法存在问题的研究及改进

碱性过硫酸钾消解紫外分光光度法测定水中总氮采用的消解器皿是玻璃比色管,易造成空白偏高、结果偏低等问题。采用双圆柱状的消解杯对水样进行消解。结果表明,消解杯消解水中总氮,线性相关系数均大于0.999,检出限为0.05 mg/L,相对标准偏差小于5%,相对误差为0.88%~1.00%;改进后的消解器皿具有较好的精密度和准确度,能够更加准确测定水中总氮的含量。     

总磷测试消解方法的选择与对比分析

选择简单可靠的消解方法是测定总磷质量保证的关键，总磷测试的消解方法较多，应根据具体情况选择。当几种方法都能适应样品分析要求时，建议首先选用过硫酸钾压力锅消解法。     

地表水中总氮测定方法的改进

测定地表水中总氮通常选用的是碱性过硫酸钾消解紫外分光光度法(HJ636-2012),但是在监测分析过程中发现,由于过硫酸钾溶解度较低,每配制200mL该试剂在不停地手工搅拌下需要1~4h左右对过硫酸钾进行溶解,非常难配制,而过硫酸钠易溶于水,用过硫酸钠配制碱性消解液比较容易,所以,通过实验用两种消解剂对总氮样品进行消解测定,比较两种试剂对校准曲线、实测样品、精密度与准确度的影响,提出了用过硫酸钠配制消解剂对地表水中总氮样品进行消解测定的实验方法。     

水中藻类对连续流动法测定总氮结果的影响

以天津市河道、水库为研究对象,在藻类增殖期采用连续流动法与碱性过硫酸钾消解法对水体中总氮进行比对监测,同时分析水中藻类分类和藻细胞密度。试验表明:虽然两种方法测定总氮的结果精密度基本相同,但二者之间的系统误差存在显著差异,连续流动法较碱性过硫酸钾消解法的测定结果低5.4%。两种方法测定总氮结果的相对偏差与水体中藻细胞密度呈正相关性,当水体中藻细胞密度﹥2.41×108L-1时,对连续流动法测定总氮的结果产生显著影响,相对偏差超过标准规范要求。     

水中汞监测存在的问题与解决办法

利用中日合作 (JICA)项目资金 ,对测定地表水中汞存在的主要问题 ,如水样的保存和处理 ,水样的消解 ,测汞的冷原子吸收法和原子荧光法等进行了研究。通过对 33个环境监测站的样品考核 ,发现测定结果与标准值相比 ,偏高的数据达 75 %以上。提出了用 1%H2 SO4 和 0 1%K2 Cr2 O7保存水样最好 ;高锰酸钾 -过硫酸钾消解法适用于消解含有机物、悬浮物和组成复杂的废水样 ,高锰酸钾 -硫酸消解法适用于消解被有机物轻度污染的废水 ,溴酸钾 -溴化钾消解法适用于消解地表水和含较少有机物的生活污水及工业废水。研究表明 :尤以硫酸 -高锰酸钾 -过硫酸钾消解体系消解地表水和废水效果良好。对冷原子吸收法和原子荧光法中影响汞测定的因素 ,如空白值高、干扰物的消除、载气种类和流量、反应瓶体积和气液比以及反应时间等提出了详尽的解决方法     

烘箱加热—碱性过硫酸钾消解—离子色谱法分析水中总氮

总氮是地表水监测的指标,目前采用的方法是碱性过硫酸钾消解—紫外分光光度法。该法操作繁琐,空白值较高及选择性较差。笔者在参考有关文献的基础上,研究了烘箱加热—碱性过硫酸钾消解—离子色谱法测定水中总氮,结果表明,该法操作简便,选择性好,测定精密度和准确度满足要求,表明该方法测定结果可靠,具有一定的应用价值。     

原子荧光度法测定城市污泥总砷的不确定度评定

根据《测量不确定度评定与表示》（JJF1059—1999），建立了原子荧光度法测定污泥泥质中砷不确定度的数学模型，分析了测试过程中不确定度的来源，并对各不确定度分量进行评定及合成，并计算得出合成不确定度和扩展不确定度。本次测量的合成相对不确定度值为0．023，其中由消化样浓度引起的相对合成不确定度为0．021；最大的不确定度分量是样品消化重复测定的不确定度，分量值为O．0152。本次测定结果为19．97±0．92mg／kg，k=2（置信水平约为95％）。     

Investigation of organic nitrogen and carbon removal in the aerobic digestion of various sludges

Nitrification and carbon removal are investigated in aerobicbatch digestion of various sludges. The experiments arecarried out with activated sludge (Test 1) and with amixture of activated and primary settling sludge (Test2). The nitrification rate was monitored, measuring theNO₂ ^- concentration. At the 3rd day of thedigestion 40.7 mg_NO2-N/l and 3.89 mg_NO2-N/l werefound in Tests 1 and 2 respectively. In a digestion process,the degradation of biomass indicates the beginning of theendogenous phase. Our measure for biomass content of thesludge was protein analysis. In Test 1, the first day valuesof 50.93 mg_TOC/ g_{dry matter}/day and 138.53mg_protein-C/g_{dry matter}/day for specific TOC andprotein-C removal rates showed, that the digestion processbegan in the endogenous phase. For Test 2, since theendogenous phase began after removal of raw organic matter inprimary settling sludge, specific TOC and protein-C removalrates were observed to be 60.12 mg_TOC/g_{dry matter}/dayand 26.72 mg_protein-C/g_{dry matter}/day,respectively.     

凯氏氮和底泥总氮的简易测定法

探讨了以简易的消化方法，蒸馏设备和最小蒸馏体积来准确测定水体中凯氏氮，亦可用于测定底泥中总氮。     

Monitoring bacterial community structure and variability in time scale in full-scale anaerobic digesters

Using a high-throughput pyrosequencing technology, this study assessed bacterial community structure and time-scale variability in great detail in seven full-scale anaerobic digesters operated variously in terms of influent substrate, digestion temperature, and reactor configuration. Pyrosequencing generated a total of 83,774 sequence reads from 40 digester sludge samples collected monthly for six months. The highest number of sequence reads were detected within Proteobacteria (20.5%), followed by those within Bacteroidetes (19.7%), Firmicutes (17.8%), and Chloroflexi (4.8%). The relative composition of bacterial populations was varied within the digesters as well as between the digesters, and the bacterial community structures were mainly influenced by digestion temperature. Detailed bacterial community structures were assessed by analyzing the operational taxonomic units (OTUs) based on 97% sequence similarity, which resulted in a total of 9051 OTUs. Among these, a total of 31 core OTUs were analyzed and inferred phylogenetically, which enabled us to classify the sequences within an unclassified phylum. Unclassified sequences were mostly affiliated with the sequences within Spirochaetes and Firmicutes. Interestingly, numerically dominant novel phylotypes (18% of the total sequence reads) presumably involved in anaerobic digestion within Spirochaetes were identified. Temporal variability was further explored using a non-metric multidimensional scaling ordination which demonstrated that the variability of the bacterial community within the digesters was smaller than between digesters. Correlation analysis demonstrated that digester performance and operational conditions affected the pattern of bacterial community in the ordination. Additionally, a multi-response permutation procedure revealed that the bacterial communities within the digesters were more similar than those belonging to other digesters statistically, demonstrating a patchiness of the digesters in the distribution of bacterial populations. Overall, this study revealed the correlation of bacterial community structure and time-scale variability with digester performance and operating conditions.     

Monitoring of growth and physiological activities of biofilm during succession on polystyrene from activated sludge under aerobic and anaerobic conditions

The present research work monitored the successive biofilm development and its catabolic role in the degradation of polystyrene (PS). PS material was artificially colonized with biofilm by incubating it with activated sludge under aerobic and anaerobic conditions. Biofilm formation was monitored by gravimetric weight analysis, spectrophotometric absorbance technique, heterotrophic plate count, and scanning electron microscopy under aerobic and anaerobic conditions. The wet weight (1.59 and 1.17 g) and dry weight (0.41 and 0.08 g) of a biofilm showed a significant constant increase under aerobic and anaerobic conditions, respectively, from first till 9 weeks of incubation. Plate count of the selected bacteria (Escherichia coli, Salmonella typhimurium, Shigella dysenteriae, Pseudomonas aeruginosa) considerably declined (90–99 %) in the biofilm after seventh and fifth weeks of incubation under aerobic and anaerobic conditions, respectively, indicating a positive shift from pathogenic to beneficial microbial community. While most probable number index of fecal coliforms and E. coli in the sludge showed more reduction (98 and 99 %) under aerobic as compare to anaerobic conditions (86 and 91 %) after 9 weeks of biofilm formation on PS cubes. Correspondingly, the decreasing levels of chemical oxygen demand and biochemical oxygen demand (up to 73 %) showed signs of sludge digestion. Scanning electron microscope coupled with energy dispersive X-ray spectroscope revealed nature of PS media containing high carbon content. However, biofilm development proved to be involved in the biochemical transformation of the PS medium as indicated by Fourier transform infrared spectroscopy.     

Environmental risk assessment of heavy metal extractability in a biosludge from the biological wastewater treatment plant of a pulp and paper mill

A five-stage sequential extraction procedure was used to fractionate heavy metals (Cd, Cu, Pb, Cr, Zn, Fe, Mn, Ni, Co, As, V and Ba) in a biosludge from the biological wastewater treatment plant of Stora Enso Oyj Veitsiluoto Mills at Kemi, Northern Finland, into the following fractions: (1) water-soluble fraction, (2) exchangeable fraction, (3) easily reduced fraction, (4) oxidizable fraction, and (5) residual fraction. The biosludge investigated in this study is a combination of sludge from the primary and secondary clarifiers at the biological wastewater treatment plant. Extraction stages (2)–(4) follow the protocol proposed by the Measurements and Testing Program (formerly BCR Programme) of the European Commission, which is based on acetic acid extraction (stage 2), hydroxylamine hydrochloride extraction (stage 3), and hydrogen peroxide digestion following the ammonium acetate extraction (stage 4). The residual fraction (stage 5) was based on digestion of the residue from stage 4 in a mixture of HF + HNO₃ + HCl. Although metals were extractable in all fractions, the highest concentrations of most of the metals occurred in the residual fraction. From the environmental point of view, it was notable that the total heavy metal concentrations in the biosludge did not exceed the maximal allowable heavy metal concentrations for sewage sludge used in agriculture, set on the basis of environmental protection of soil by European Union Directive 86/278/EEC, and by the Finnish legislation. The Ca (98.6 g kg⁻¹; dry weight) and Mg (2.2 g kg⁻¹; dry weight) concentrations in the biosludge were 62 and 11 times higher than the typical values of 1.6 and of 0.2 g kg⁻¹ (dry weight), respectively, in arable land in Central Finland. The biosludge had a slightly alkaline pH (∼8.30), a high loss-on-ignition value (∼78%) and a liming effect of 10.3% expressed as Ca equivalents (dry weight). This indicates its potential as a soil conditioner and improvement agent, as well as a pH buffer.     

A perspective on the prevalence of DNA enteric virus genomes in anaerobic-digested biological wastes

The major goal of this study is to gain a perspective on the prevalence of DNA enteric virus genomes in mesophilic anaerobic-digested (MAD) sewage sludge and manure by comparing their quantitative PCR (qPCR) concentrations and removals with traditional fecal indicators (Escherichia coli, enterococci, and Bacteroidetes). In addition, relationships between qPCR and culture measurements of fecal indicators (FIs) were determined. There was no significant difference between the qPCR concentrations of human adenovirus and E. coli/enterococci in MAD sewage sludge; however, the qPCR concentrations of bovine adenovirus were significantly lower than FIs and bovine polyomavirus (BPyV) in MAD manure. The qPCR concentrations of human polyomavirus were slightly lower than E. coli and enterococci (p ≤ 0.05), but no significant difference was observed between the qPCR concentrations of BPyV and FIs. The digestion treatment achieved higher genome removal of bovine DNA enteric viruses than FIs (p ≤ 0.05). Significant correlations were observed between qPCR and culture measurements of FIs, but the concentrations and removals of FIs determined by qPCR assays were still significantly different than those determined by culture assays. Overall, we determined that the prevalence of DNA enteric virus genomes in MAD biological wastes was high due to their comparable in qPCR concentrations to FIs, indicating that mesophilic anaerobic digestion treatment alone may not be effective enough to remove DNA viral pathogens in biological wastes.     

微波消解—原子吸收/原子荧光光度法测定活性污泥中的Cd、Pb、Ni、Cu、Zn、Cr、K、As、Hg

通过实验,建立了活性污泥中金属和重金属的测定方法。活性污泥样品经硝酸—氢氟酸或硝酸—高氯酸微波消解处理后,Pb、Ni、Cu、Zn、Cr、K选用火焰原子吸收分光光度法测定,Cd用石墨炉原子吸收分光光度法测定,As、Hg用原子荧光光度法测定。该方法操作简单,结果准确,重现性好。样品加标回收率为93%-108%,相对标准偏差〈5%。     

Recycling of petroleum-contaminated sand

The environmental impact of using petroleum-contaminated sand (PCS) as a substitute in asphalt paving mixtures was examined. An appreciable component of PCS is oily sludge, which is found as the dregs in oil storage tanks and is also produced as a result of oil spills on clean sand. The current method for the disposal of oily sludge is land farming. However, this method has not been successful as an oil content of < 1% w/w is required, and difficulty was encountered in reaching this target. The reuse of the sludge in asphalt paving mixtures was therefore considered as an alternative. Standard tests and environmental studies were conducted to establish the integrity of the materials containing the recycled sludge. These included physical and chemical characterization of the sludge itself, and an assessment of the mechanical properties of materials containing 0%, 5%, 22% and 50% oily sludge. The blended mixtures were subjected to special tests, such as Marshall testing and the determination of stability and flow properties. The experimental results indicated that mixtures containing up to 22% oily sludge could meet the necessary criteria for a specific asphalt concrete wearing course or bituminous base course. To maximize the assay from the recycled material, the environmental assessment was restricted to the 50% oily sludge mixture. Leachates associated with this particular mixture were assayed for total organic residue and certain hazardous metal contaminants. The results revealed that the organics were negligible, and the concentrations of the metals were not significant. Thus, no adverse environmental impact should be anticipated from the use of the recycled product. Our research showed that the disposal of oily sludge in asphalt paving mixtures could possibly yield considerable savings per tonne of asphalt concrete, and concurrently minimize any direct impact on the environment.     

Conditioning of Oily Sludge with Alum

Sludge dewatering is a process whereby water is removed from sludge so as to reduce its volume and alter its physical state from semisolid to damp solid. This physical change reduces the volume of sludge considerably and therefore the cost of disposal. The degree of reduction of sludge volume or dewatering is a function of the characteristics of sludge and the type of dewatering device. Sludge characteristics such as specific resistance, capillary suction time(CST), filter yield and solid content can be determined in the laboratories. Knowledge of these characteristics with different dosages of sludge conditioners helps in effective dewatering and sludge handling operations.Oil and grease have an affinity for suspended solids. Experiences show that the presence of oil in wastewater results in poor substrate utilization causing less aerobic treatment and subsequently hinder settling and dewatering processes. Sludge samples with different oil contents varying from 1.8% to 8.0% by weight have been examined in the laboratory to find out their specific resistance, capillary suction time and filter yield. Alum was used as a conditioner. Different dosages of alum varying from 2% to 12% by weight were used to determine the optimum chemical dosage for varying oil contents. Buchner funnel apparatus, filter leaf apparatus and capillary suction time test apparatus were used to determine the dewatering characteristics specific resistance, filter yield and capillary suction time respectively.Addition of alum decreases the specific resistances and capillary suction times of oily sludges rapidly upto 4% dosages. Alum dosages beyond 4% only increase the solids content in the sludge cake and increase the sludge volume to be handled. The total suspended solids of filtrate decrease with alum dosage. The correlations between dewatering characteristics were studied. A correlation between CST and specific resistance to filtration was established. CST can be measured easily and quickly in the laboratories. Using the CST and the correlation a quick prediction on dewaterability can be established.