Occurrence and migration of microplastics and plasticizers in different wastewater and sludge treatment units in municipal wastewater treatment plant

● Reduce the quantifying MPs time by using Nile red staining. ● The removal rate of MPs and PAEs in wastewater and sludge were investigated. ● MPs and PAEs were firstly analyzed during thermal hydrolysis treatment. ● The removal of PAEs from wastewater and sludge was mainly biodegradation. Microplastics (MPs) and plasticizers, such as phthalate esters (PAEs), were frequently detected in municipal wastewater treatment plants (MWTP). Previous research mainly studied the removal of MPs and PAEs in wastewater. However, the occurrence of MPs and PAEs in the sludge was generally ignored. To comprehensively investigate the occurrence and the migration behaviors of MPs and PAEs in MWTP, a series of representative parameters including the number, size, color, shape of MPs, and the concentrations of PAEs in wastewater and sludge were systematically investigated. In this study, the concentrations of MPs in the influent and effluent were 15.46±0.37 and 0.30±0.14 particles/L. The MP removal efficiency of 98.1% was achieved and about 73.8% of MPs were accumulated in the sludge in the MWTP. The numbers of MPs in the sludge before and after digestion were 4.40±0.14 and 0.31±0.01 particles/g (dry sludge), respectively. Fourier Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that the main types of MPs were polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), and polystyrene (PS). Six PAEs, including phthalate (DMP), diethyl phthalate (DEP), diisobutyl phthalate (DIBP), ortho dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), and bis(2-ethyl) hexyl phthalate (DEHP), were detected in the MWTP. The concentrations of total PAEs (ΣPAEs) in the influent and effluent were 76.66 and 6.28 µg/L, respectively. The concentrations of ΣPAEs in the sludge before and after digestion were 152.64 and 31.70 µg/g, respectively. In the process of thermal hydrolysis, the number and size of MPs decreased accompanied by the increase of the plasticizer concentration.     

Relationship between groundwater cadmium and vicinity resident urine cadmium levels in the non-ferrous metal smelting area,China

● This study systematically examined the relationship between groundwater Cd and UCL. ● The study covered 211 UCL and sociological characteristic from nine groundwater samples. ● We found a significant positive correlation between groundwater Cd and UCL. ● Smoking status and education level also significantly affected UCL. Cadmium (Cd) has received widespread attention owing to its persistent toxicity and non-degradability. Cd in the human body is mainly absorbed from the external environment and is usually assessed using urinary Cd. Hunan Province is the heartland of the Chinese non-ferrous mining area, where several serious Cd pollution events have occurred, including high levels of Cd in the urine of residents. However, the environmental factors influencing high urinary Cd levels (UCLs) in nearby residents remain unclear. Therefore, 211 nearby residents’ UCLs and the corresponding sociological characteristics from nine groundwater samples in this area were analyzed using statistical analysis models. Groundwater Cd concentration ranged from 0.02 to 1.15 μg/L, aligning with class III of the national standard; the range of UCL of nearby residents was 0.37–36.60 μg/L, exceeding the national guideline of 0–2.5 μg/L. Groundwater Cd levels were positively correlated with the UCL (P < 0.001, correlation coefficient 95 % CI = 9.68, R² = 0.06). In addition, sociological characteristics, such as smoking status and education level, also affect UCL. All results indicate that local governments should strengthen the prevention and abatement of groundwater Cd pollution. This study is the first to systematically evaluate the relationship between groundwater Cd and UCL using internal and external environmental exposure data. These findings provide essential bases for relevant departments to reduce Cd exposure in regions where the heavy metal industry is globally prevalent.     

Microbial responses to the use of NaClO in sediment treatment

• Chlorine addition enhanced the release of TOC, TN from the sediment. • Chlorine has a long-term negative effect on microbial richness. • Usually enzymes lose activity, and expression of genes was downregulated. • Carbon degradation and nitrification might be strongly inhibited. Chlorine is often used in algal removal and deodorization of landscape waters, and occasionally used as an emergency treatment of heavily polluted sediments. However, the ecological impact of this practice has not been fully studied and recognized. In this study, NaClO at 0.1 mmol/g based on dry weight sediment was evenly mixed into the polluted sediment, and then the sediment was incubated for 150 days to evaluate its microbial effect. Results showed that NaClO addition enhanced the release of TOC, TN, Cr and Cu from the sediment. The microbial richness in the examined sediment decreased continuously, and the Chao1 index declined from 4241 to 2731, in 150 days. The microbial community composition was also changed. The abundance of Proteobacteria and Bacteroidetes increased to 54.8% and 4.2% within 7 days compared to the control, and linear discriminant analysis (LDA) showed gram-negative bacteria and aerobic bacteria enriched after chlorination. The functional prediction with PICRUSt2 showed the functions of the microbial community underwent major adjustments, and the metabolic-related functions such as carbon metabolism, including pyruvate and methane metabolisms were significantly inhibited; besides, 15 out of 22 analyzed key enzymes involved in C cycling and 6 out of 12 key enzymes or genes involved in N cycling were strongly impacted, and the enzymes and genes involved in carbon degradation and denitrification showed remarkable downregulation. It can be concluded that chlorination posed a seriously adverse effect on microbial community structure and function. This study deepens the understanding of the ecological effects of applying chlorine for environmental remediation.     

板材类生物质燃烧及动力学特性热重研究

采用非等温升温法研究了4种板材类生物质在空气气氛下的燃烧特性和动力学特性。通过对TG、DTG等曲线的分析,发现4种板材燃烧过程均可分成3个阶段,即水分蒸发阶段、挥发份析出(或燃烧)阶段和固定碳燃烧阶段。综合燃烧特性:松木集成材>纤维密度板>夹芯胶合板>刨花板。4种板材均具有良好的燃烧特性。4种生物质燃烧均存在1个吸热峰和2个放热峰,分别与挥发分析出峰、挥发分燃烧、固定碳燃烧对应。采用Fridman法和Fridman-Carroll法分别对4种板材的动力学参数进行了计算,2种方法得出的结果符合较好。分析得出:由于生物质燃烧与环境换热、挥发分析出吸热、固定碳燃烧放热等因素作用,4种生物质的表观活化能高温区均低于低温区。动力学计算结果表明:松木集成材平均表观活化能最低,燃烧反应能较容易进行。     

混凝-生物强化联合处理环氧树脂高盐废水

环氧树脂高盐废水是目前较难处理的工业废水之一.采用混凝联合生物强化工艺:通过混凝过程进行预处理后,投加嗜盐菌进行生物强化考察盐度变化对系统降解有机物的影响以及污泥性状的变化情况.结果表明,当废水中氯离子浓度达到驯化目标10 g/L时,系统对COD的去除率仍稳定在85％左右;以没有投加嗜盐菌的反应器为对照组,在进水COD平均浓度为550 mg/L左右,氯离子浓度由12 g/L增至21 g/L时,对照组COD平均去除率由82％降至60％以下,而投加了嗜盐菌的反应器(投加组)则仍保持在85％以上;此外,盐度的变化同时影响污泥的活性及其沉降性能,随着盐度增大,两组中的污泥活性均有所降低,但投加组的污泥活性相对较高,其污泥的沉降时间和污泥体积指数(sludge volume in-dex,SVI)值也较低.采用本工艺处理环氧树脂高盐废水,使得生物处理过程能够长期稳定运行,且能够保持较高的耐盐度和COD去除率.     

铬渣的热解无害化处理

采用热解工艺无害化处理铬渣,探讨了稻秆在铬渣无害化处理中的作用.研究了热解温度、稻秆与铬渣质量比、铬渣粒径及保温时间对铬渣热解无害化处理的影响,并分析了热解前后热解产物中铬元素形态的变化.结果表明,热解工艺能有效地将铬渣中Cr(Ⅵ)还原,稻秆热解过程中产生的气相挥发分对Cr(Ⅵ)的还原起核心作用.较为适宜的热解条件:热解温度为400 ℃,稻秆与铬渣质量比为0.10,铬渣粒径<2 000 μm,保温时间为10 min.在该热解条件处理下,热解产物中的Cr(Ⅵ)质量浓度为121 mg/kg,低于热解前铬渣中的Cr(Ⅵ)(3 400 mg/kg).热解后,可交换态及碳酸盐结合态铬含量降低,大部分铬转化成了稳定的有机结合态和残渣态,极大地降低了铬渣的危害.第一作者:张大磊,男,1982生,博士研究生,研究方向为固体废弃物热处理.     

煅烧的水滑石同时去除水体中砷和氟

为探讨水滑石类材料对水体中氟、砷离子的同时去除效果,采用共沉淀法合成(Mg∶Al=2∶1)纳米类水滑石(LDHs),用傅立叶转换红外光谱、电子扫描透射电镜、X射线晶体衍射等手段对合成的材料进行了表征,并研究纳米材料在不同初始浓度、pH、吸附时间、阴离子干扰条件下其同时除砷氟性能。结果表明,煅烧后的水滑石(LDOs)对砷最大吸附量为51.02 mg/g,对氟最大吸附量为36.63 mg/g。吸附动力学实验表明,煅烧水滑石对砷的吸附在前6 h内基本完成,对氟的吸附在前10 h内基本完成。砷氟共存溶液保持pH=4~10及pH=6~8时,水滑石分别对砷、氟保持良好的吸附效率。对比不同阴离子对水滑石共除砷氟效率的影响,水滑石除砷速率受到阴离子影响力大小为:HPO2-4CO2-3NO-3Cl-SO2-4;水滑石除氟速率受到阴离子影响力大小为:CO2-3HPO2-4SO2-4Cl-NO-3。材料再生循环利用4次后,对砷和氟的吸附效率均能达到90%以上。实验结果表明,所合成的水滑石是一种优秀的能共除砷氟的吸附剂。     

不同因素对人工湿地基质脱氮除磷效果的影响

在人工配制的污水中投入一定量的基质,不同条件下振荡培养,评价沸石、炉渣和陶瓷滤料3种基质在不同因素影响下对氨氮(NH4+-N)和总磷(TP)的吸附能力。结果表明,不同吸附时间时,沸石对NH4+-N的吸附效果最好,陶瓷滤料对TP的吸附效果最好;进水浓度对沸石吸附NH4+-N的影响较大,其吸附量随进水浓度的增大而增大,进水浓度对炉渣和陶瓷滤料吸附NH4+-N及炉渣吸附TP影响不大;3种基质对NH4+-N和TP的吸附量均是随吸附剂量的增加而降低,要达到较好的去污效果,应根据实验结果考虑基质投入量;pH值对沸石吸附NH4+-N影响显著,pH值6～7范围内吸附效果最好,pH值8～12的碱性条件有利于基质对TP的吸附。     

Removal of PAHs with surfactant-enhanced soil washing: influencing factors and removal effectiveness

PAH removal with surfactant enhanced washing was investigated through a series of laboratory tests to examine the effect of stirring speed, washing time, surfactant concentration, liquid/solid ratio, temperature, and on-and-off mode. The first four factors show significant influence on the PAH removal while the latter two do not. Total removal ratio and a new proposed parameter, solubilization percentage, are used to evaluate the effectiveness quantitatively.     

不同诱导条件对结晶产物形貌特征的影响

在流化床反应器中,以含铜废水为处理对象,重点考察了诱导条件改变对结晶系统运行效率及结晶产物形貌特征的影响。结果表明,进水200 mg/L,进药比([Cu2+]/[CO2-3])1∶1.2,p H为10.2的条件下,铜离子去除率可接近100%,诱导晶种表面平滑,诱导颗粒生长成致密杆状晶体结构,以碳酸盐为沉淀剂的诱导结晶系统依赖于体系的p H,高p H体系下发生的共结晶现象是影响系统运行的主要原因;随着进药摩尔比的增加,结晶产物由短杆状向球状转化,晶体机械强度显著降低大量破碎,影响出水水质;进药比1∶1.2,p H为11的条件下,含铜废水浓度为500 mg/L时,系统去除率可达95%以上,微晶产率低于5%。