Antimony leaching release from brake pads: Effect of pH,temperature and organic acids

Metals from automotive brake pads pollute water, soils and the ambient air. The environmental effect on water of antimony (Sb) contained in brake pads has been largely untested. The content of Sb in one abandoned brake pad reached up to 1.62 × 10⁴ mg/kg. Effects of initial pH, temperature and four organic acids (acetic acid, oxalic acid, citric acid and humic acid) on Sb release from brake pads were studied using batch reactors. Approximately 30% (97 mg/L) of the total Sb contained in the brake pads was released in alkaline aqueous solution and at higher temperature after 30 days of leaching. The organic acids tested restrained Sb release, especially acetic acid and oxalic acid. The pH-dependent concentration change of Sb in aqueous solution was best fitted by a logarithmic function. In addition, Sb contained in topsoil from land where brake pads were discarded (average 9 × 10³ mg/kg) was 3000 times that in uncontaminated soils (2.7 ± 1 mg/kg) in the same areas. Because potentially high amounts of Sb may be released from brake pads, it is important that producers and environmental authorities take precautions.     

Antimony in brake pads-a carcinogenic component?

Antimony trisulfide (Sb₂S₃) is used as a lubricant in friction material. X-ray diffraction analysis revealed Sb in 3/3 disc brake pads (range 41,000–46,000 mg/kg) and in 2/2 disc brake dust samples (21,000 and 17,000 mg/kg) from trucks. Considerably lower concentrations were found in drum brake pads (3/5, 59–6400 mg/kg) and in drum brake dust (4/18, 78–2800 mg/kg). Other toxic metals were also detected in pads and dust.The health risk of Sb in particulate brake emissions should be dependent on particle size and chemical entity, in particular solubility. A significant amount of the emitted dust was shown by size-fractionated optical particle counting to be inhalable in environmental (>90% mass) and occupational (>50% mass) exposure situations. Differentiation via selective solubility showed a considerable amount of Sb₂S₃ to oxidize during the braking process, likely leading to the formation of Sb₂O₃, a suspected human carcinogen. Sb in brake dust was soluble in calf serum (8.5±1.2%, 8.9±1.7 mg/l at 37 °C for 3 d).Hence, the use of Sb in friction material should be suspected to pose a human cancer risk and be deterred. To design healthy and environmentally sound alternatives, we propose to apply the Intelligent Product System that distinguishes products of consumption and products of service. Brake pads are true products of consumption, because they are released to biological cycles, and should thus consist of materials with positively defined health and environmental properties.     

淋洗剂对多金属污染尾矿土壤的修复效应及技术研究

以我国南方某多金属复合污染尾矿土壤为研究对象,对土壤中重金属全量和各形态含量进行分析.通过系列振荡淋洗试验研究了蒸馏水、草酸、柠檬酸、乙酸、硝酸和EDTA对污染土壤的淋洗效果,筛选合适的淋洗剂及其最佳的液土比、液洗时间、淋洗次数等技术参数,并提出利用综合毒性消减指数来综合评价淋洗剂对污染土壤的修复效果.结果表明,该土壤以Cd和Pb污染最为严重,含量分别达52.2 mg.kg-1和4 836.5 mg.kg-1;淋洗剂对土壤中不同重金属元素的淋洗效果差异明显,其中对Cr的去除率最高仅为2.7%,而最多能去除约60%的Cd和Pb;蒸馏水对重金属几乎没有脱除效果,去除率都在0.1%以下,草酸和乙酸对重金属的去除率也较低,0.1 mol.L-1的EDTA是适合的高效淋洗剂;基于综合毒性消减指数和经济成本,选择在1∶6土水比2次淋洗3 h的技术条件.     

化学合成类制药行业工艺废气VOCs排放特征与危害评估分析

以浙江台州6家典型化学合成类制药企业为代表,对其排放工艺废气中的18项挥发性有机物(VOCs)特征污染物(如甲苯、甲醛、二氯甲烷等)进行监测和分析,并采用臭氧产生潜力(OFP)和健康风险评价指标对VOCs所产生的环境与健康危害进行初步的评价.结果表明,化学合成类制药企业排放的总VOCs浓度为14.9~308.6 mg·m-3,其产生环境危害的OFP值为3.1~315.1 mg·m-3,主要贡献物质为甲苯、四氢呋喃、乙酸乙酯等6种物质,存在较大的潜在环境危害.另外,健康危害中的非致癌风险指数和总致癌风险指数介于9.48×10-7~4.98×10-4a-1和3.17×10-5~6.33×10-3之间,主要是苯、甲醛和二氯甲烷这3种致癌物.     

Pathway of the ozonation of 2,4,6-trichlorophenol in aqueous solution

The reaction mechanism and pathway of the ozonation of 2,4,6-trichlorophenol (2,4,6-TCP) in aqueous solution were investigated. The removal efficiency and the variation of H₂O₂, Cl⁻ formic acid, and oxalic acid were studied during the semi-batch ozonation experiments (continuous for ozone gas supply, fixed volume of water sample). The results showed that when there was no scavenger, the removal efficiency of 0.1 mmol/L 2,4,6-TCP could reach 99% within 6 min by adding 24 mg/L ozone. The reaction of molecular ozone with 2,4,6-TCP resulted in the formation of H₂O₂. The maximal concentration of H₂O₂ detected during the ozonation could reach 22.5% of the original concentration of 2,4,6-TCP. The reaction of ozone with H₂O₂ resulted in the generation of a lot of OH• radicals. Therefore, 2,4,6-TCP was degraded to formic acid and oxalic acid by ozone and OH• radicals together. With the inhibition of OH• radicals, ozone molecule firstly degraded 2,4,6-TCP to form chlorinated quinone, which was subsequently oxidized to formic acid and oxalic acid. Two reaction pathways of the degradation of 2,4,6-TCP by ozone and O₃/OH• were proposed in this study. Translated from Acta Scientiae Circumstantiae, 2005, 25(12): 1619–1623 [译自: 环境科学学报]     

A high activity of Ti/SnO2-Sb electrode in the electrochemical degradation of 2,4-dichlorophenol in aqueous solution

Electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Ti/SnO₂-Sb anode. The factors influencing the degradation rate, such as applied current density (2-40 mA/cm²), pH (3-11) and initial concentration (5-200 mg/L) were evaluated. The degradation of 2,4-DCP followed apparent pseudo first-order kinetics. The degradation ratio on Ti/SnO₂-Sb anode attained > 99.9% after 20 min of electrolysis at initial 5-200 mg/L concentrations at a constant current density of 30 mA/cm² with a 10 mmol/L sodium sulphate (Na2SO4) supporting electrolyte solution. The results showed that 2,4-DCP (100 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9% and 92.8%, respectively, at the optimal conditions after 30 min electrolysis. Under this condition, the degradation rate constant (k) and the degradation half-life (t_1/2) were 0.21 min^-1 and (2.8±0.2) min, respectively. Mainly carboxylic acids (propanoic acid, maleic acid, propanedioic acid, acetic acid and oxalic acid) were detected as intermediates. The energy efficiencies for 2,4-DCP degradation (5-200 mg/L) with Ti/SnO₂-Sb anode ranged from 0.672 to 1.602 g/kWh. The Ti/SnO₂-Sb anode with a high activity to rapid organic oxidation could be employed to degrade chlorophenols, particularly 2,4-DCP in wastewater.     

锑矿冶炼区周边土壤吸附Sb (V)的行为研究

本文通过吸附平衡和动力学实验方法对Sb（V）在锑矿冶炼区周边土壤表面开展吸附行为研究,用常用的等温吸附模型和动力学吸附模型分别对等温吸附曲线和动力学吸附曲线进行拟合。结果表明：Langmuir与Freundlich模型对荒地土和林地土吸附Sb（Ⅴ）的等温吸附曲线均有较好的拟合效果,拟合系数R²0.988。荒地土对Sb（Ⅴ）的吸附能力大于林地土,其吸附量是林地土的2.9±0.2倍,这与Langmuir模型预测的该两种土壤的吸附倍数相当,荒地土表现出强烈吸附Sb（Ⅴ）的能力,尤其在锑浓度较高的体系中更为明显。结合土壤基本理化性质及矿物学特征,认为土壤秥粒、铁矿物和碳酸钙是影响土壤吸附Sb（V）的主要因素。有机质对土壤吸附Sb（Ⅴ）有一定促进作用,但这种影响只表现在Sb（Ⅴ）初始浓度低的条件下;而在Sb（Ⅴ）初始浓度高的条件下,有机质对土壤吸附Sb（Ⅴ）的影响不明显。土壤吸附Sb（Ⅴ）的过程分为快速吸附和慢速吸附两个阶段,快速反应发生在70 min以内。初始浓度低（0.01 mmol/L）的条件下,Elovich方程能够很好地拟合荒地土和林地土吸附Sb（V）的动态曲线;初始浓度高（2 mmol/L）的条件下,双常数方程对荒地土吸附Sb（V）的拟合效果较好,拟一级动力学方程和拟二级动力学方程则适用于拟合林地土吸附Sb（V）的过程。     

Immobilization of lead in anthropogenic contaminated soils using phosphates with/without oxalic acid

Understanding the effects of oxalic acid (OA) on the immobilization of Pb(II) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(II) by KH₂PO₄, phosphate rock (PR), activated phosphate rock (APR) and synthetic hydroxyapatite (HAP) at different phosphate:Pb (P:Pb) molar ratios (0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or CaCl₂, Community Bureau of Reference (BCR) sequential extraction and toxicity characteristic leaching procedure (TCLP) methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after 120 days was reduced by 100% when soils were amended with APR, HAP and HAP + OA, and the TCLP-Pb was <5 mg/L for the red soil at P:Pb molar ratio 4.0. Water-soluble Pb could not be detected and the TCLP-Pb was <5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APR was most effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pb molar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.     

Biochemical and microbial soil functioning after application of the insecticide imidacloprid

Imidacloprid is one of the most commonly used insecticides in agricultural practice, and its application poses a potential risk for soil microorganisms. The objective of this study was to assess whether changes in the structure of the soil microbial community after imidacloprid application at the field rate (FR, 1 mg/kg soil) and 10 times the FR (10× FR, 10 mg/kg soil) may also have an impact on biochemical and microbial soil functioning. The obtained data showed a negative effect by imidacloprid applied at the FR dosage for substrate-induced respiration (SIR), the number of total bacteria, dehydrogenase (DHA), both phosphatases (PHOS-H and PHOS-OH), and urease (URE) at the beginning of the experiment. In 10× FR treated soil, decreased activity of SIR, DHA, PHOS-OH and PHOS-H was observed over the experimental period. Nitrifying and N₂-fixing bacteria were the most sensitive to imidacloprid. The concentration of NO₃^- decreased in both imidacloprid-treated soils, whereas the concentration of NH₄⁺ in soil with 10× FR was higher than in the control. Analysis of the bacterial growth strategy revealed that imidacloprid affected the r- or K-type bacterial classes as indicated also by the decreased eco-physiological (EP) index. Imidacloprid affected the physiological state of culturable bacteria and caused a reduction in the rate of colony formation as well as a prolonged time for growth. Principal component analysis showed that imidacloprid application significantly shifted the measured parameters, and the application of imidacloprid may pose a potential risk to the biochemical and microbial activity of soils.     

Antimony smelting process generating solid wastes and dust：Characterization and leaching behaviors

A large amount of solid waste has been produced by the antimony smelting process in the＂World Capital of Antimony＂, Xikuangshan area in China. This study comprehensively investigated the physical and chemical characteristics of the various solid wastes, as well as the leaching behavior of the solid wastes, which included water-quenched slag,arsenic-alkali residue, desulfurized slag and blast furnace dust. These four types of waste were enriched in a variety of heavy metals and metalloids and more specifically with As and Sb levels up to 8.6 × 104 and 3.16 × 105mg/kg, respectively, in arsenic-alkali residue. For desulfurized slag and water-quenched slag, the leaching concentration of Sb significantly exceeded the acceptable limits during the leaching tests using the toxicity characteristic leaching procedure and the synthetic precipitation leaching procedure. In addition, As leaching in arsenic-alkali residue was extraordinarily hazardous, being three orders of magnitude higher than the regulatory level of As. According to the results of the extraction tests, all the tested wastes were classified as hazardous waste.     

福建省茶园土壤-茶叶的铅含量及铅同位素示踪

运用微波消解-电感耦合等离子体质谱法(ICP-MS)分析了福建省内9个市县的茶园土壤和茶叶的铅含量及铅同位素组成,评价铅污染情况并解析铅来源。结果表明,茶园土壤和茶叶的铅含量分别为23.00±0.099~55.43±0.032 mg/kg和0.53±0.126~1.47±0.058 mg/kg,地质累积指数法表明茶园土壤基本为无污染,单项因子指数法表明茶叶均为安全等级。茶园土壤和茶叶铅同位素组成具有区域性,茶叶铅同位素组成相对于茶园土壤具有较低的206Pb/207Pb和206Pb/208Pb。结合铅含量相关性分析和铅同位素示踪分析,福建省茶叶铅主要来源于茶园土壤和大气。福建省茶叶铅同位素组成的同地相似性和异地差异性特征可为茶叶产地溯源和鉴别提供一定的科学依据和参考价值。     

许昌市典型区域土壤磁化率与有机质含量的相关性研究

为探讨土壤磁化率对有机质含量的指示作用,对许昌市典型区域土壤磁化率与有机质含量的相关性进行研究,结果显示:研究区域土壤样品Xlf变化范围在15×10~(-8)~125×10~(-8)m~3/kg,平均值为64×10~(-8)m~3/kg,说明研究区土壤样品中磁性矿物含量较低。Xfd值在4.67%~26.67%之间,平均值为10.02%,反映了样品中超顺磁颗粒含量很高,说明研究区域土壤磁性矿物主要由自然成土作用形成,现代工业生产活动和人类的生活活动贡献较小。土壤有机质含量范围为3.74~31.93 g/kg,均值为17.09 g/kg。研究区域土壤磁化率与有机质含量呈不显著正相关性,反映了在长期人工施肥活动和城市化进程中人类活动导致土壤各理化因子之间发生学联系的弱化。     

Immobilization of lead in anthropogenic contaminated soils using phosphates with/without oxalic acid

Understanding the effects of oxalic acid (OA) on the immobilization of Pb(II) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(II) by KH₂PO₄, phosphate rock (PR), activated phosphate rock (APR) and synthetic hydroxyapatite (HAP) at different phosphate:Pb (P:Pb) molar ratios (0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or CaCl₂, Community Bureau of Reference (BCR) sequential extraction and toxicity characteristic leaching procedure (TCLP) methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after 120 days was reduced by 100% when soils were amended with APR, HAP and HAP + OA, and the TCLP-Pb was < 5 mg/L for the red soil at P:Pb molar ratio 4.0.Water-soluble Pb could not be detected and the TCLP-Pb was < 5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APRwasmost effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pbmolar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.     

模拟三峡库区消落带优势植物根系低分子量有机酸对土壤中铅的解吸动力学

三峡库区消落带落干期时会生长大量植被,其根系分泌的低分子量有机酸会对消落带土壤中重金属的活化带来一定影响,为此,本研究通过水培法以及利用去离子水直接浸提其根际土测出三峡库区优势植物狗牙根和稗草根系分泌的低分子量有机酸种类和含量,并模拟优势植物所分泌的单一有机酸和混合有机酸分别对消落带土壤中的铅(Pb)进行解吸,探究其对消落带土壤中铅的解吸动力学.结果表明,狗牙根根系分泌的低分子量有机酸种类和含量均大于稗草,其中柠檬酸、丙二酸、乙酸、苹果酸是两种植株根系均分泌的有机酸,且乙酸含量最高,分别为0.765 mmol·kg-1、0.261 mmol·kg-1,而在狗牙根和稗草根际土中均检测到柠檬酸、丙二酸、乙酸;选取柠檬酸、丙二酸、乙酸对消落带土壤中铅进行解吸时,发现当有机酸浓度≤1 mmol·L~(-1)时,有机酸解吸量由高到低为:丙二酸柠檬酸乙酸;而当有机酸浓度1 mmol·L~(-1)时,有机酸解吸量由高到低为:柠檬酸丙二酸乙酸,且低分子量有机酸在土壤中含量低时,抑制土壤对Pb的解吸;含量高时,促进土壤对Pb的解吸.在解吸过程中,0~240 min为快反应阶段,240 min后为慢反应阶段,准二级动力学方程拟合效果最好.     

低分子有机酸对土壤中Cu化学形态的影响

向石英砂岩坡积物发育的红壤中添加系列浓度CuSO4模拟土壤Cu污染,然后加入不同浓度的低分子量有机酸培养,采用改进的BCR连续提取法评价低分子有机酸对重金属Cu形态的影响.结果表明,对不同程度的Cu污染(Cu 0～400mg·kg-1)土壤,随着有机酸添加浓度的升高,最具活性的弱酸溶解态Cu含量均有不同程度的提高,土壤重金属Cu得到活化;Cu活化效果随柠檬酸浓度升高而升高,随酒石酸和草酸浓度升高呈先上升后基本不变趋势;整体活化效果是柠檬酸>酒石酸≈草酸.可还原态Cu随着有机酸浓度的增加而减少,其中添加柠檬酸的处理减少最明显.当有机酸浓度为10 mmol·kg-1、20 mmol·kg-1时,酒石酸和草酸、柠檬酸活化Cu效果分别达到最优.     

基于物种敏感度分布法建立中国土壤中锑的环境基准

基于Sb（锑）的植物及动物毒理学数据缺乏以及保护生态受体的土壤Sb的环境基准尚未建立的现状,通过收集和筛选文献中Sb的毒理学数据并补充开展不同土壤类型的跳虫和植物的毒理学试验,建立了Sb的生物毒性预测模型,并以此为依据对收集及试验毒理学数据进行归一化处理,以消除土壤性质的影响.此外,进一步利用SSD（species sensitivity distribution,物种敏感度分布法）推导我国4种典型情景土壤中Sb的HC₅（hazardous concentration,能够保护95%物种的生态安全阈值）,最终建立基于土壤性质参数的环境基准计算模型.结果表明:①不同土壤中Sb对跳虫的毒性差异较大,跳虫毒性阈值EC₁₀（effect concentration,10%抑制效应浓度）与土壤pH呈负相关,与w（SOC）（SOC为土壤有机碳）呈正相关,即随着土壤pH增加或w（SOC）降低,Sb对跳虫的生物有效性随之增加,进而导致EC₁₀降低.②通过毒性阈值与土壤性质之间的多元回归分析可知,土壤pH和SOC可较好地预测Sb的生物毒性,植物和无脊椎动物的R2（决定系数）分别为0.778和0.867.③利用SSD得到11个物种在4种典型情景土壤中的HC₅分别为55.12、28.28、28.08及14.55 mg/kg,推导出PNEC_total（predicted no effect concentration,预测无效应浓度）分别为28.96、15.54、15.44及8.68 mg/kg,计算模型为PNEC_total=-5.811pH+0.587[SOC]+55.480+C_b（[SOC]为土壤有机碳含量,C_b土壤Sb背景浓度）.鉴于此,建议以中性土壤中Sb的环境基准值作为我国农用地土壤Sb污染风险筛选值制订的参考依据,即农用地土壤w（Sb）限值定为15 mg/kg.      

3种低分子量有机酸对紫色土吸附菲的影响

采用静态吸附实验,研究了3种低分子量有机酸(柠檬酸、苹果酸和草酸)对紫色土吸附菲的影响.结果表明紫色土吸附菲的动力学过程符合二级动力学模型,3种低分子量有机酸(LMWOAs)均能显著降低紫色土吸附菲的速率常数;线性吸附模型很好地描述了紫色土对菲的吸附热力学过程是以分配作用为主.当加入的3种LMWOAs浓度低于5 mmol·L~(-1)时,促进紫色土吸附菲;当LMWOAs浓度≥10 mmol·L~(-1)时,抑制紫色土吸附菲,抑制作用随LMWOAs浓度的增加而加强.当LMWOAs浓度为20 mmol·L~(-1)时,其抑制作用能力表现为柠檬酸草酸苹果酸,这与3种LMWOAs的分子结构和酸性强弱有关.与对照相比,随着LMWOAs浓度的增加,紫色土溶出的溶解性有机质(DOM)含量呈现先降低后升高的趋势,紫色土对菲的吸附量与土壤溶出的DOM含量呈负相关.     

贵州某锑冶炼厂周边农田土壤锑、砷污染与人体健康风险评估

本研究以贵州省独山县某锑冶炼厂周边农田土壤为研究对象,系统采集17个土壤样品,测定了土壤中Sb、As总含量,并采用生理提取试验(PBET)和简化生物可给性提取试验(SBET)两种体外胃肠模拟实验方法分析了土壤中Sb、As的生物可给态含量,基于土壤Sb、As总量和生物可给性(PBET和SBET)评估了研究区锑、砷污染土壤暴露引起的潜在人体健康风险。结果表明:研究区农田土壤锑、砷污染严重,土壤中Sb(55.63±75.59 mg/kg)和As(44.31±38.34 mg/kg)的平均含量均超过贵州省区域背景值和我国农用地土壤污染风险筛选值;土壤中SBET和PBET提取的生物可给态Sb和As含量和计算得到的生物可给性都较低,大多数样品的生物可给性低于40%。相对于元素总量,基于Sb和As生物可给性(PBET和SBET)的人体非致癌风险(HQ和HI)和致癌风险(CR)均显著降低,其中成人和儿童的非致癌风险值均降至安全值范围,但是As的致癌风险除了CR_SBET-成人降至安全水平,CR_PBET-成人、CR_SBET-儿童以及CR_PBET-儿童值仍处于1.0E-06~1.0E-04之间,表明As对当地成人和儿童的潜在致癌风险仍不容忽视,特别是儿童。     

近40年来福建省水稻土有效磷富集效应及潜在生态风险评估

水稻土磷素流失引起的水体富营养化等生态风险已受到普遍关注,而明确其动态变化和富集效应是制定合理防控措施的基础.以福建省1.8×10⁶ hm²水稻土为研究对象,以1982年全国第二次土壤普查1 471个、 2008年农业农村部测土配方施肥项目215 534个和2018年农业农村部耕地质量监测项目2 895个表层水稻土样点建立的1∶5万三期大比例尺土壤数据库为基础,分析全省水稻土有效磷含量近40年来的富集效应及潜在生态风险.结果表明,1982～2018年间福建省水稻土有效磷含量增加了47 mg·kg^-1,富集面积达到1.65×10⁶ hm²,占全省水稻土总面积的91%;其中,1982～2008年福建省水稻土有效磷含量增加了28 mg·kg^-1,富集面积为1.47×10⁶ hm²,占全省水稻土总面积的82%; 2008～2018年福建省水稻土有效磷含量增加了19 mg·kg^-1,富集面积为1.22...     

Research on polyhydroxyalkanoates and glycogen transformations: Key aspects to biologic nitrogen and phosphorus removal in low dissolved oxygen systems

In this paper, a study was conducted on the effect of polyhydroxyalkanoates (PHA) and glycogen transformations on biologic nitrogen and phosphorus removal in low dissolved oxygen (DO) systems. Two laboratory-scale sequencing batch reactors (SBR1 and SBR2) were operating with anaerobic/aerobic (low DO, 0.15–0.45 mg·L⁻¹) configurations, which cultured a propionic to acetic acid ratio (molar carbon ratio) of 1.0 and 2.0, respectively. Fewer poly-3-hydroxybutyrate (PHB), total PHA, and glycogen transformations were observed with the increase of propionic/acetic acid, along with more poly-3-hydroxyvalerate (PHV) and poly-3-hydroxy-2-methyvalerate (PH2MV) shifts. The total nitrogen (TN) removal efficiency was 68% and 82% in SBR1 and SBR2, respectively. In the two SBRs, the soluble ortho-phosphate (SOP) removal efficiency was 94% and 99%, and the average sludge polyphosphate (poly-P) content (g·g-MLVSS⁻¹) was 8.3% and 10.2%, respectively. Thus, the propionic to acetic acid ratio of the influent greatly influenced the PHA form and quantity, glycogen transformation, and poly-P contained in activated sludge and further determined TN and SOP removal efficiency. Moreover, significant correlations between the SOP removal rate and the (PHV + PH2MV)/PHA ratio were observed (R ²>0.99). Accordingly, PHA and glycogen transformations should be taken into account as key components for optimizing anaerobic/aerobic (low DO) biologic nitrogen and phosphorus removal systems.