Influence of Pyrolytic Biochar on Settleability and Denitrification of Activated Sludge Process

Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.

Comparative short-term effects of sewage sludge and its biochar on soil properties, maize growth and uptake of nutrients on a tropical clay soil in Zimbabwe

Soil application of biochar from sewage could potentially enhance carbon sequestration and close urban nutrient balances. In sub-Saharan Africa, comparative studies investigating plant growth effect and nutrients uptake on tropical soils amended with sewage sludge and its biochar are very limited. A pot experiment was conducted to investigate the effects of sewage sludge and its biochar on soil chemical properties, maize nutrient and heavy metal uptake, growth and biomass partitioning on a tropical clayey soil. The study compared three organic amendments; sewage sludge （SS）, sludge biochar （SB） and their combination （SS＋SB） to the unamended control and inorganic fertilizers. Organic amendments were applied at a rate of 15 t ha-1 for SS and SB, and 7.5 t ha-1 each for SS and SB. Maize growth, biomass production and nutrient uptake were significantly improved in biochar and sewage sludge amendments compared to the unamended control. Comparable results were observed with F, SS and SS＋SB on maize growth at 49 d of sowing. Maize growth for SB, SS, SS＋SB and F increased by 42, 53, 47, and 49%, respectively compared to the unamended control. Total biomass for SB, SS, SS＋SB, and F increased by 270,428, 329, and 429%, respectively compared with the unamended control. Biochar amendments reduced Pb, Cu and Zn uptakes by about 22% compared with sludge alone treatment in maize plants. However, there is need for future research based on the current pot experiment to determine whether the same results can be produced under field conditions.

Pyrolysis of different sewage sludge feedstocks for biochar products:Characterization and application

Four sewage sludge(SS)feedstocks with distinct properties were converted into biochars by pyrolysis at 300−700℃,in order to clarify the effects of the composition difference of SS feedstocks.The yields of biochars present a positive correlation with the contents of ash in SS.Notedly,the contents of organic matter(OM)in SS largely determine the quality of biochars.SS feedstocks with high content of OM are more likely to form stable biochars with higher aromaticity/carbonization degree,and the formed biochars possess higher calorific values.The contents of residual OM in biochars derived from SS feedstocks with low content of OM likely fail to meet the needs of soil improvement(10 wt.%).Most of heavy metals(HMs)existing in raw SS are remained in biochars after pyrolysis.The biochar produced from SS feedstocks with high content of HMs usually contains higher contents of HMs.Surprisingly,the leachability of HMs in biochars is all weakened to some extent compared to raw SS.In addition,the biochars show higher thermal stability and pH values,and P/K nutrients are enriched in biochars.The biochars prepared from four SS feedstocks exhibit different adsorption ability of methylene blue,especially at low dosage of biochar.

β-FeOOH Modified Sludge Biochar as Efficient Adsorbent for Phosphate Removal

β⁃FeOOH modified sludge biochar(FSBC)was prepared and investigated in this work to remove phosphate from water via adsorption.FSBC exhibited superior adsorption performance for phosphate with the maximum adsorption amount of 27.17 mg/g at 25℃.The specific adsorption capacity of FSBC was 57.8%higher than that of commercial activated carbon at pH 5 with the initial phosphate concentration of 10 mg/L.Coexisting anions can inhibit the adsorption of phosphate,but cations(Cr(VI)and Cd^(2+))exhibited some promotion effect.The results of kinetic and isotherm models and characterization analysis in combination indicated chemical adsorption,as electrostatic interaction,metal phosphate precipitation and hydrogen bonding may be the dominant process.The adsorption of phosphate onto FSBC was a monolayer adsorption,and the process was endothermic.After four adsorption/desorption cycles,the adsorption capacity of FSBC for phosphate decreased by 36.4%,which was in a distinct comparison with the 57.5%of SBC.

A novel strategy of tannery sludge disposal–converting into biochar and reusing for Cr(Ⅵ)removal from tannery wastewater

Tannery sludge with high chromium content has been identified as hazardous solid waste due to its potential toxic effects.The safety disposal and valorization of the tannery sludge remains a challenge.In this study,the chromium stabilization mechanism was systematically investigated during chromium-rich tannery sludge was converted to biochar and the removal performance of the sludge biochar(SBC)for Cr(Ⅵ)from tannery wastewater was also investigated.The results showed that increase in pyrolysis temperature was conductive to the stabilization of Cr and significant reduction of the proportion of Cr(Ⅵ)in SBC.It was confirmed that the stabilization of chromium mainly was attributed to the embedding of chromium in the C matrix and the transformation of the chromium-containing substances from the amorphous Cr(OH)_(3)to the crystalline state,such as(FeMg)Cr_(2)O_(5).The biochar presented high adsorption capacity of Cr(Ⅵ)at low pH and the maximal theoretical adsorption capacity of SBC produced at 800°C can reach 352 mg Cr(Ⅵ)/g,the process of which can be well expressed by Langmuir adsorption isotherm and pseudo second order model.The electrostatic effect and reduction reaction were dominantly responsible for the Cr(Ⅵ)adsorption by SBC800.Overall,this study provided a novel strategy for the harmless disposal and resource utilization for the solid waste containing chromium in leather industry.

污泥生物炭对水体中磷的吸附

以污水处理厂剩余污泥(RS)制备成的污泥生物炭(SDBC)作为吸附剂,采用批平衡法研究SDBC对磷的吸附特征,考察投加量、溶液pH值等因素对SDBC吸附磷的影响,并通过响应面法(RSM)对影响磷吸附的条件进行优化,结合实验结果与表征数据对SDBC吸附磷的机制进行探究.结果表明,SDBC对磷的吸附动力学符合Elovich(R^(2)=0.984)方程,说明SDBC对磷的吸附过程是多种反应共同作用的非均相扩散过程;Langmuir(R^(2)=0.980)和Langmuir-Freundlich(R^(2)=0.979)方程能很好地描述磷在SDBC上的吸附行为,由Langmuir拟合所得的磷最大吸附量为4.508mg/g;Langmuir-Freundlich模型拟合均相指数n(1.143)较小,说明SDBC上吸附位点分布不均匀,SDBC与磷之间存在相互作用力.SDBC吸附磷的最佳初始pH值为4.0~5.0;SDBC对磷吸附的最佳投加量为8g/L.通过RSM分析得到SDBC对磷的最佳吸附条件为SDBC的投加量为5g/L,磷的初始浓度c0为10mg/L,pH为5.0.SDBC对磷吸附的可能机制包括静电吸附作用,共沉淀作用,置换作用,配体交换作用以及孔隙填充作用.

污泥生物炭添加对黑麦草和土壤养分特性的影响

为探讨污泥生物炭(Sludge biochar,C)和改性污泥生物炭(Modified sludge biochar,GC)添加对黑麦草(Lolium perenne L.)和土壤养分特性的影响,本试验以C和GC为材料,设置不同添加水平(0%,5%,10%,15%,20%)种植黑麦草,测定黑麦草和土壤养分等指标。结果表明,添加C、GC均促进了黑麦草的生长及其茎叶和根含水量的提高,5%的添加水平显著提高了黑麦草茎叶和根的干重。C、GC添加对黑麦草TN含量的提高效果最显著,其次为TK。C添加对提高黑麦草生物量的影响程度大于GC,而对黑麦草养分含量及其吸收累积,GC大于C。应用C、GC可提高土壤有机质和全氮含量,降低土壤pH,碱解氮和速效磷受生物炭类型影响。因此,土壤中添加5%~10%比例的C或GC对植物的生长有促进作用,有利于提高土壤的养分含量。

活性污泥生物炭的制备及吸附性能的研究进展

污水处理厂产生大量剩余污泥,其处置问题一直以来是研究的重点与热点。利用热解的方法将污泥转化为污泥基生物炭,不但可以解决剩余污泥的处置问题,而且可以在处理污废水的基础上,对剩余污泥实现重新利用。污泥基生物炭在污废水的处理中逐渐受到了关注,尤其是在新兴污染物的去除方面。以污水处理厂污泥为基础的污泥生物炭,分别通过制备方式、热解温度、改性手段等因素综述污泥生物炭对重金属、有机物、新兴污染物的影响,并通过用图表的形式指出改变之后的作用与机理。以期能给今后污泥生物炭在重金属、有机物、新兴污染物领域上的应用和研究提供更多的思路。

农林废弃物共热解对污泥生物炭Cu(Ⅱ)吸附性能的影响

将山地城市污泥与水稻杆、水稻壳、桉树枝、桉树叶等农林废弃物进行共热解,研究共热解对生物炭理化性质及Cu(II)吸附性能的影响,探讨共热解对Cu(II)吸附性能的协同作用。结果显示,与污泥炭相比,水稻壳、水稻杆、桉树枝、桉树叶与污泥共热解制备的生物炭,C含量分别增大了0.64倍、0.87倍、1.04倍、1.22倍,O含量分别增大了1.11倍、1.25倍、2.01倍、2.17倍,对Cu(II)最大吸附量分别增大了28.4%,60.3%,82.7%,99.7%。共热解对生物炭Cu(II)吸附性能具有明显的协同作用,污泥与桉树叶共热解炭对Cu(II)最大吸附量的协同量化值最高(90.13%)。

焦化污泥基生物炭在氯介质下催化降解间甲酚的性能

以焦化污泥制备生物炭,并在硝酸溶液中低温条件下进行改性,研究其在氯介质下对间甲酚降解的效率与机理.焦化污泥(CSS)具有较大的比表面积和丰富的官能团,其吸附作用较强,对间甲酚的吸附去除率为27.1%.而通过炭化和改性的焦化污泥炭的比表面积显著降低,官能团数量减少,吸附作用极弱.在催化降解过程中,改性焦化污泥炭(CSSC-N)对间甲酚和总有机碳(TOC)的去除率分别为98.1%和80.1%,远高于未改性的焦化污泥炭(CSSC-0),主要归因于CSSC-N中具有多种含铁物质,有利于铁循环,且表面铁含量高达60.10%,能提供丰富的催化活性组分.Cl-对间甲酚和TOC的去除率有抑制作用,随着Cl-浓度的升高,去除率降低.当废水中的NaCl为5%wt时,在催化重复实验中间甲酚的去除率均高于70%.CSSC-N具有一定的抗氯性能,在氯介质下具有较高的催化活性和稳定性.三维荧光光谱分析和中间产物鉴定结果表明Cl-的存在影响了间甲酚的降解过程,生成了难降解的氯代副产物.

生物炭改善污泥脱水性能及其机理研究进展

介绍了污泥脱水性能的主要影响因素和污泥脱水调理技术,综述了生物炭的特征、改性方法及其单独或与其他方法联合用于污泥调理的研究进展,并对影响污泥脱水性能的相应机理进行了探讨。对生物炭调理技术的发展与应用前景进行了展望,提出深入探究生物炭改性方式以及联合调理方法以进一步提高污泥脱水性能的必要性,以期为生物炭在污泥调理理论研究和工程应用等方面提供参考。

高含量金属对污泥生物炭磷形态与释放的影响

将市政污泥经高含量金属强化预处理后低温热解制备成不同生物炭,采用Pearson相关分析和表征分析方法探讨了高含量金属和热解温度对污泥生物炭磷形态及磷释放的影响.结果表明,污泥生物炭的磷释放量随热解温度升高而降低,内源磷于350℃大量转变为正磷酸盐(ortho-P),强化预处理和pH值更加影响磷释放和金属元素固定,Fe/Al-P与Ca-P竞争共存且Fe/Al-P略占优势,Ca-P则对无机磷(IP)形态影响显著.高含量金属抑制磷释放、促进有机磷(OP)向IP转化以及阻碍HPO_(4)^(2-)向H_(2)PO_(4)^(-)转化的能力排序均为Fe>Al>Ca,钙基和铁基/铝基污泥生物炭的优势磷分别为Ca-P和Fe/Al-P,其中Fe/Al-P被铁铝氧化物包被而更难释放,主要磷释放形态均为Ca(H_(2)PO_(4))_(2).Fe强化预处理对磷形态与释放的影响最大,Ca强化预处理利于提高生物有效磷,可为污泥生物炭的资源化利用提供新思路.

市政污泥生物炭在废水吸附处理中的应用

随着经济全球化的飞速发展,城市污水处理中排放的污泥量日益增加,预计到2025年中国市政污泥年产量将>9.0×10^(7) t。市政污泥中含有的病原微生物、有机物及重金属,会对环境和人体健康造成严重危害。污泥衍生的生物炭材料因其较大的比表面积、优良的孔结构以及丰富的含氧基团,被广泛应用于废水吸附处理领域,实现了固体废物再利用和去除污染的双重目的,做到以废治废,达到生态与发展的双赢。该文总结了市政污泥生物炭的制备及改性方法,介绍了吸附的影响因素,综述了市政污泥生物炭在吸附重金属、染料、无机盐、抗生素、酚类中的应用及其吸附机理;最后,指出了未来污泥生物炭的发展方向和需攻克的难题,应努力形成绿色低碳的资源化处理体系。

污泥生物炭对土壤养分及重金属的影响

采用未、酸、碱改性污泥生物炭(SC1、SC2、SC3)修复受重金属单一污染(Cu、Zn、Cd)的土壤,研究生物炭对土壤理化性质、养分指标及重金属形态分布的影响。结果表明,施加三种SC后,土壤pH值与电导率均显著增加;阳离子交换量、有机质、有效磷及速效钾等养分指标也均呈现积极影响,即阳离子交换量在SC3的处理下提升效果更好,有机质与有效磷含量在SC2的处理下增加更为显著,速效钾含量的提升均在50%左右;三种重金属则在SC3的处理下修复固化效果更好。

含油污泥基生物炭处理含油废水

为使含油污泥达到无害化处理、资源化利用的目的,本实验通过热解炭化的方法,以含油污泥为实验原料,氧化钙、粉煤灰和十六烷基三甲基溴化铵的混合物为调质剂,玉米秸秆为增碳剂,制备含油污泥基生物炭,并研究其对含油废水中石油类污染物的吸附性能。以石油类污染物去除率为指标,对比了ZnCl_(2)、KOH和H_(2)SO_(4)三种活化剂对生物炭吸附性能的影响;通过扫描电子显微镜、傅里叶变换红外光谱、BET测试法等手段分析了生物炭的比表面积、孔隙结构和表面官能团等性能;采用批量吸附实验和再生实验,研究生物炭对石油类污染物吸附性能及其再生性。研究结果表明,最佳活化剂为H_(2)SO_(4),H_(2)SO_(4)活化制备的生物炭含有大量孔隙结构且多为介孔,生物炭表面存在—CH、C==O、—OH和C==C等官能团,比表面积为71.8069m2/g。在生物炭投加量为1.8g/L、吸附时间为180min时,对200mg/L含油废水中石油类污染物去除率可达98.21%,对石油类污染物最大吸附量为99.32mg/g。生物炭吸附石油类污染物的过程符合准二级动力学方程和Freundlich模型,主要受化学吸附控制的多分子层吸附。此外,三次再生后的生物炭孔隙结构、表面官能团、比表面积与新炭相比差别不大,吸附不同浓度的含油废水中石油类污染物,生物炭的三次再生效率均达到了90%以上,仍具有良好的吸附性能,能满足循环使用的要求。

铁-钙-炭强化污泥深度脱水及污泥基生物炭制备

污泥脱水是污泥处置及资源化的重要前提。在实际工程中,常规使用FeCl_(3)作为污泥调理剂时,对于某些剩余污泥的强化脱水效果较差,无法满足后续处置的含水率要求。本研究以脱水困难的剩余污泥为研究对象,探究了FeCl_(3)、CaO和生物炭协同强化污泥深度脱水效果及其资源化利用途径。研究发现,在FeCl_(3)调理污泥脱水的最佳条件下,引入CaO和生物炭可以进一步提高脱水效果。对于脱水困难的剩余污泥(单独FeCl_(3)调理,最佳脱水情况下泥饼含水率仍有60%~70%),当FeCl_(3)投加剂量为9%、CaO投加剂量为2%、稻壳生物炭投加剂量为2%,压滤时间为7 min时,机械脱水后泥饼含水率可降低至44.08%,满足后续处置的含水率要求,并且滤液pH接近中性,不会增加滤液处理负担。脱水后的泥饼中含有Fe、Ca元素,在400℃条件下制备高性能污泥基生物炭,具有较高的比表面积和孔容,表面富含含氧官能团,可以高效去除水中Cr^(6+),吸附量为26.51 mg/g。本研究建立了铁-钙-炭协同强化污泥深度脱水及其制备高性能污泥基生物炭的技术策略,为难脱水剩余污泥的处理和资源化利用提供了科学依据和技术参考。

钠化污泥生物炭复合凹凸棒石对水体中Cu^(2+)的吸附效果研究

含铜废水严重威胁人体健康和环境安全,利用废弃污泥和凹凸棒石制备了钠化污泥生物炭复合凹凸棒石材料,并将其用于含Cu^(2+)废水的处理。利用SEM、XRD及FT-IR对材料的结构和表面性质进行了分析表征,复合材料表面的含氧官能团的络合或C=C键的Π电子作用是吸附重金属的主要机制。研究了复合材料对Cu^(2+)的吸附效果和机理,结果表明,污泥/凹凸棒石质量比2∶1,pH=5,添加量为1.5 g/L,Cu^(2+)初始浓度4 mg/L条件下,材料对Cu^(2+)有最大的吸附容量为3.339 mg/g。吸附过程更好地拟合了准二级动力学模型和Langmuir吸附等温式,表明材料对Cu^(2+)的吸附是单分子层化学吸附。利用响应面分析法预测,pH值为5.04,吸附剂添加量1.16 g/L,Cu^(2+)初始浓度3.60 mg/L是最佳吸附条件。钠化污泥生物炭复合凹凸棒石在实际含铜废水处理中是一种极具潜力的吸附剂。

氮硫共掺杂污泥生物炭吸附水中2,4,6-三氯苯酚的研究

【目的】2,4,6-三氯苯酚(2,4,6-TCP)因其具有强毒性、“三致”效应被列入水中污染物黑名单,处理水中的2,4,6-TCP意义重大。【方法】以市政污泥为原料,采用浸渍-热解法制备得到氮硫共掺杂污泥生物炭(Sx-NSC800),并将其用于吸附水溶液中的2,4,6-TCP;采用扫描电子显微镜、比表面及孔径分析仪、X射线衍射仪、傅立叶红外光谱仪等仪器对Sx-NSC800的结构特征和表面化学性质进行了表征;采用拟一级、拟二级动力学模型拟合了吸附动力学曲线。【结果】Sx-NSC800对2,4,6-TCP有良好的吸附效果,180min左右接近吸附/解吸平衡,其中S10-NSC800效果最好,其吸附量为14.424mg/g;吸附数据与拟二级模型具有良好的相关性;采用经典的等温线模型进行拟合,结果更符合Freundlich等温模型,表明Sx-NSC800对2,4,6-TCP的吸附行为容易发生,升温有利于吸附;同时吸附是一个自发进行且混乱度增加的过程。吸附机制涉及孔隙填充、氢键作用及π-π相互作用。

污泥生物炭的制备及其对亚甲基蓝的吸附研究

以污水处理厂中剩余污泥为原料,通过一步热解法,在缺氧条件下制备出不同温度梯度(300,500,700,750℃)的污泥生物炭,测定最佳热解温度制备出的污泥生物炭对亚甲基蓝的吸附性能,并通过BET、FTIR和形貌方法进行表征分析。结果表明,在缺氧条件下700℃热解1 h制备的污泥生物炭对亚甲基蓝去除效果最好,去除率可达97.9%。在35℃的反应温度,生物炭投加量10 g/L,吸附平衡时间12 h条件下,SB700对亚甲基蓝的理论吸附量9.87 mg/g,拟二级动力学模型对SB700吸附亚甲基吸附过程的拟合相关系数(R^(2))为0.9878,高于拟一级动力学模型,表明吸附过程以单分子的化学吸附为主。

污泥共热解制备污泥基生物炭及其在土壤回用中的改良效益

随着全球污泥产量的快速增长,对其的资源化处置是亟待解决的现实问题.相较于传统的填埋以及新型的焚烧工艺,污泥热解可实现污泥的无害化、减量化并生成具有土壤改良潜力的污泥基生物炭,是污泥处理的一种较优选择.本文以市政污泥为研究对象,全面综述了污泥不同热解方法对生成污泥基生物炭的物化性质和其对土壤改良效应的影响,重点介绍了污泥中磷和重金属在不同热解工艺中的迁移转化机制,污泥基生物炭对土壤物化性质的影响机理、对污染土壤的修复机制、对土壤中微生物和微生物酶等的作用机制.通过以上分析,能够以此为理论支撑指导制备具有定向改良土壤功能的污泥基生物炭.本综述将有助于污泥定向热解制备污泥基生物炭的进一步发展,为污泥基生物炭土壤改良提供理论参考和支持.