Efficient stabilization of dredged sludge with high water content using an improved bio-carbonation of reactive magnesia cement method

This study proposed an improved bio-carbonation of reactive magnesia cement(RMC)method for dredged sludge stabilization using the urea pre-hydrolysis strategy.Based on unconfined compression strength(UCS),pickling-drainage,and scanning electron microscopy(SEM)tests,the effects of prehydrolysis duration(T),urease activity(UA)and curing age(CA)on the mechanical properties and microstructural characteristics of bio-carbonized samples were systematically investigated and analyzed.The results demonstrated that the proposed method could significantly enhance urea hydrolysis and RMC bio-carbonation to achieve efficient stabilization of dredged sludge with 80%high water content.A significant strength increment of up to about 1063.36 kPa was obtained for the bio-carbonized samples after just 7 d of curing,which was 2.64 times higher than that of the 28-day cured ordinary Portland cement-reinforced samples.Both elevated T and UA could notably increase urea utilization ratio and carbonate ion yield,but the resulting surge in supersaturation also affected the precipitation patterns of hydrated magnesia carbonates(HMCs),which weakened the cementation effect of HMCs on soil particles and further inhibited strength enhancement of bio-carbonized samples.The optimum formula was determined to be the case of T?24 h and UA?10 U/mL for dredged sludge stabilization.A 7-day CA was enough for bio-carbonized samples to obtain stable strength,albeit slightly affected by UA.The benefits of high efficiency and water stability presented the potential of this method in achieving dredged sludge stabilization and resource utilization.This investigation provides informative ideas and valuable insights on implementing advanced bio-geotechnical techniques to achieve efficient stabilization of soft soil,such as dredged sludge.

Modification of nanoparticles for the strength enhancing of cementstabilized dredged sludge

This paper investigates the effectiveness of nano-modification on the strength enhancement of cementstabilized dredged sludge(CDS).Three types of nanoparticles including nano-SiO2(NS),nano-Al2O3(NA)and nano-MgO(NM)were used as cement admixtures for dredged sludge stabilization.Effects of single nanoparticle content,mass ratio of composite nanoparticles and curing time on the strength development of CDS were evaluated via a series of unconfined compressive strength(UCS)tests.The pH evolutions of CDS caused by nanoparticles were also examined by a range of pH tests.Furthermore,micromechanisms reflecting the strength evolutions were analyzed by performing scanning electron microscopy(SEM)and X-ray diffraction(XRD)tests.The results indicated that adding nanoparticles can significantly improve the UCS of CDS.For single nano-modification,the optimum contents of NS,NA and NM were 4%e6%,6%and 8%,which can increase the 7-and 28-d UCSs of CDS by 38%and 50%,17%and 35%,65%and 67%,respectively.Compared with single nano-modification,composite nano-modifications were more effective in improving the strength gain of CDS.The optimum mass ratios of composite nanoparticles,namely NS/NA,NS/NM and NA/NM,were 9/1,3/7 and 3/7,respectively.Based on the strength growth rate,the composite nanoparticles with NS/NM of 3/7 were highly recommended.The addition of nanoparticles obviously affected the pH evolution of CDS,which was mainly determined by the difference of OHproduction and consumption inside nano-modified CDS.The microstructural analysis revealed that C-S-H and C-A-H gels are the main cementitious products,and the addition of nanoparticles can obviously contribute to a denser and more homogenous microstructure of CDS.

Simulation of sludge－dredging effects in controlling nutrient release of LakeKasumigaura with large－size core samples

Nutrient release from the dredged and undredged sediments in Lake Kasumigaura were simulated under the laboratory control conditions with large-size core samples. It was found that phosphate and ammonia release fluxes are less in aerobic than those in anaerobic. In different simulated dredged depth, the phosphate release showed large divergence in the anaerobic than in the aerobic. There was a larger accumulated release of phosphate and ammonia at actual dredged (St. B) than the undredged (St. A) in anaerobic condition. This showed that the sludge-dredging was effective of controlling phosphorus and nitrogen release. A preliminary assessment is drawn from the experiments that the sludge-dredging work in Tsuchiura Bay of Lake Kasumigaura can reduce about 15. 9% of phospbate and 56. 2% of anunonia release from the sediments respectively.

Municipal sludge as landfill barrier material

The aim of this research is to find substitute barrier materials for natural clay from two kinds of municipal sludge: waterworks sludge(S_w) and dredging sludge(S_d). Laboratory tests were performed firstly to determine their Atterberg limits and hydraulic conductivity. Based on the results, the use of waterworks sludge was recommended. Then, shear strength tests were performed and it was found the shear resistance property of waterworks sludge is strong enough to maintain slope stability. In order to evaluate the possibility of secondary pollution, the heavy metal contents of waterworks sludge was determined and the results indicated that secondary pollution is unlikely happened. Finally, economic analysis proves that reusing waterworks sludge as barrier will reduce the lost a great for both landfill and waterworks. Based on the results, waterworks sludge was proposed to use and a further long-term simulated landfill test was suggested.

改良垃圾焚烧底渣固化疏浚淤泥性能试验研究

基于以废治废理念,提出了用改良垃圾焚烧底渣固化疏浚淤泥的新思路,并开展了室内试验研究,测定了固化淤泥试样的含水率、无侧限抗压强度及抗剪强度指标。试验结果表明:垃圾焚烧底渣磨细粉和未研磨的原渣按1∶1比例混合时,具有最优的固化性能;在最优混合比条件下,固化淤泥的无侧限抗压强度、黏聚力和内摩擦角均随龄期和改良垃圾焚烧底渣掺入比的增加而增大,含水率则相反;当改良垃圾焚烧底渣掺入比为35%时,固化淤泥28 d无侧限抗压强度达到了58.4 kPa,含水率由67.4%降至38.0%,采用改良垃圾焚烧底渣固化疏浚淤泥是可行的。

含聚污水重力沉降分离过程淤泥增长特性预测

重力沉降作为污水处理的基本工艺,其常用设施重力沉降罐在运行过程中,来水中的悬浮物会不断向罐底沉积形成淤泥,为了防止水质二次污染,保障设施的高效运行,需根据淤泥量来制定清淤方案。文章基于大庆某油田污水处理站运行实际,从日处理量、含聚浓度、悬浮物含量、含油量、悬浮物脱除率等特征量出发,通过构建重力沉降罐清淤数据集,分析各特征量间的关系,并确定影响淤泥增长的主导因素,进而基于BP神经网络架构建立淤泥增长速率预测模型。研究结果表明,污水中含聚浓度在一定程度上影响含油量和悬浮物含量,随着沉降罐日处理量的增加,油珠脱除率和悬浮物脱除率降低,淤泥增长速率正相关于污水悬浮物含量、悬浮物脱除率和含聚浓度,基于生产数据训练的预测模型拟合度分布在0.9以上,满足精度要求,为污水沉降罐清淤操作的时间选择提供了依据和方法。

泡沫添加量对淤泥免烧陶粒的性能影响

以疏浚淤泥为主要原料,创新性引进空气泡沫制备免烧陶粒,探究了空气泡沫添加量对陶粒孔隙率的影响,以及孔隙率对陶粒性能的影响。结果表明,在水灰比0.35、灰土比3、养护时间7 d条件下,随着空气泡沫的增加,陶粒孔隙率从14.90%增加至32.23%,密度从1144.32 kg/m^(3)下降至792.68 kg/m^(3),强度从8.96 MPa大幅下降至4.68 MPa,1 h吸水率从17.74%波动下降至14.56%,所制备的陶粒为700密度等级的普通陶粒。空气泡沫在陶粒制备过程中损耗81.49%。陶粒密度与总孔隙率线性相关,强度与孔隙率呈指数关系,1 h吸水率与开口孔隙率线性相关。空气泡沫的增加主要是提高了陶粒闭口孔隙率,从而提高总孔隙率,陶粒内部孔隙孔径集中在0~200μm之间,陶粒孔隙率越大,其内部大孔径孔隙占比也越大。

引江济淮工程疏浚抛泥区淤泥污染特征与评价

以引江济淮工程巢湖疏浚抛泥区淤泥为研究对象,开展了淤泥中重金属和氮磷等营养物质的污染特征分析,并进行了重金属污染生态风险评价和氮磷污染评价。结果表明,重金属汞的污染程度和潜在风险较高,重金属潜在生态风险以中风险和高风险为主。淤泥中总氮、总磷浓度最大值超出背景值达1.95倍和0.73倍。总氮标准指数、总磷标准指数、综合污染指数、有机氮、有机指数评价结果表明,淤泥中氮磷以轻度污染和中度污染为主。

PHD疏浚淤泥堆场大应变非线性固结分析

已有的工程实践和室内模型试验均表明铺设水平排水板(Prefabricated Horizontal Drains,PHDs)可有效加快疏浚淤泥的固结。但目前自重作用下能全面反映疏浚淤泥特性的PHD处理疏浚淤泥堆场的大应变固结理论尚缺乏系统性研究。针对底层铺设PHD的疏浚淤泥堆场具有平面渗流、竖向应变的特点,基于Gibson大应变固结理论,考虑疏浚淤泥的非线性压缩和渗透特性,建立PHD处理的疏浚淤泥堆场大应变非线性固结模型,并应用有限差分法获得该模型的解答。通过与疏浚淤泥自重作用下未设置PHD的大应变固结模型解答开展对比分析,验证了PHD处理疏浚淤泥堆场大应变非线性固结模型及其解答的可靠性。在此基础上,分析了不同影响因素对疏浚淤泥堆场大应变固结的影响。分析发现:铺设率达到一定值后就可达到与底部完全透水边界相同的固结速率,且该值随堆放高度的增加而曲线减小;堆放高度分别为1,5 m时,PHD最佳铺设率分别约为50%,27%;堆放高度对PHD处理堆场的固结速率影响较大,可通过增设PHD层数以加快堆场的固结速率;淤泥压缩指数一定时,固结速率随渗透指数的增大而增大;渗透指数保持不变时,固结速率随压缩指数的增大而减小。

河道淤泥疏浚和底泥污染评价研究——以三亚市某河道为例

为选择更有效更环保更经济的底泥清淤方式及淤泥处置方案,研究采用平行断面法和潜在生态危害指数法调查和分析了三亚市某河道的沉积物营养盐、有机质及重金属污染特征及污染程度,并根据污染程度初步确定是否需要清淤、清淤范围、深度和工程量。结果表明:(1)河道的底泥主要受到有机质和总磷污染,对水体的富营养化有潜在影响。(2)清淤淤泥富含有机质、氮、磷等营养元素,是一种优质的土壤改良剂。河道底泥中重金属的含量均符合《绿化种植土壤》(CJ/T340-2016)I级标准限值,清淤出的底泥可以直接或者经过干化处理后作为绿化种植土,用于园林绿化的土壤改良剂或客土置换。河道清淤的全过程研究对于其他河道淤泥监测评估及相应清淤疏浚施工及淤泥资源化处置方式的选择提供参考借鉴。

基于氧化/混凝的污泥和疏浚泥浆泥水分离技术探讨

在污水处理、河湖疏浚过程中,必不可免会产生副产物污泥和疏浚泥浆,其体积大且含水率高。为避免对环境二次污染,减少堆放面积,国内外研究者均对污泥和疏浚泥浆高效泥水分离减容方法展开了系统研究。本文综述了采用氧化、混凝以及氧化协同混凝方法进行污泥和疏浚泥浆泥水分离的研究进展,并提出了基于氧化/混凝的污泥和疏浚泥浆泥水分离技术研究和发展方向。

河湖疏浚淤泥资源化技术研究进展与应用

河湖疏浚淤泥产量巨大、成分复杂。经济高效的疏浚淤泥资源化利用技术对促进疏浚污泥资源化利用具有重要意义。目前,经济有效的资源化利用方法依然缺乏。本文结合前人的研究与工程试验,将淤泥资源化技术分为4类,并系统梳理了4类技术的主要进展及其应用现状。固化处理类尚缺乏具有普适性的固化剂配方及固化剂信息数据库,固化效果受到限制,并且缺乏实际应用参考价值;建材利用类的效率不高,限制了淤泥消纳量,需要探索新的优化技术;土地利用类消纳量大,但对辅助介质材料的要求较高,并且无法保证对重金属等污染物的稳定控制;堆肥处理类降低了对辅助介质的要求,但同样存在二次污染的安全问题,以及对时间和空间的占用问题。本文还进一步归纳了现有技术,从两个角度对疏浚淤泥资源化技术的发展进行了思考。从工程化的角度看,固化处理的化学手段与建材利用的物理方法能够有机结合,同时引入工程技术,可能是未来工程化利用淤泥的主要发展方向;从自然化的角度看,应该统一土地利用与堆肥处理两种类的物质转化机理,为有效资源利用和污染物控制策略的提出奠定基础。总体而言,未来研究需要在优化现有技术的淤泥消纳量和拓展新的资源化路线两个方向进行努力,以更高效和更经济地解决疏浚淤泥的去向问题。

排水管道淤积物特性分析及清除措施

排水管道淤积严重,会威胁城市排水系统的正常运行,导致污水回流和环境污染。通过对淤积物特性的分析,探讨了淤积物产生的原因及对城市环境的影响。并通过介绍传统清淤技术,提出了创新的清淤方案。排水管道淤积物有泥沙、各种生活垃圾,而出现的原因有降雨时颗粒物沉积、管道设计缺陷、垃圾排放等。淤积物会影响生态环境,引发洪涝,产生污染以及增加维护成本。传统的清淤技术如机械清淤、高压冲洗等不适用于出现疑难问题的管道。清理淤积物的创新方案,如智能监测系统、无人机巡检、局部壁清洗等,既提高了清淤效率,也降低了维护成本。同时,深入了解淤积物特性以及采用创新的清淤方法可解决排水问题,保障城市排水通畅,降低洪涝风险,提高人民的生活质量,为城市可持续发展提供保障。

不同辅助胶凝材料下泡沫混凝土的性能研究

泡沫混凝土作为一种轻质、多功能建筑材料,因其低密度、优异的隔热和吸声性能,在轻型结构、隔热隔音和填充材料等方面展示出了巨大的潜力。为了进一步优化其性能并减少环境影响,对不同辅助胶凝材料在泡沫混凝土制备中的应用效果进行了分析。重点论述了粉煤灰、疏浚淤泥对泡沫混凝土性能的影响,其中包括密度、吸水率和抗压性能等。研究结果表明,在水灰比为0.5的情况下,6%的过氧化氢可以在保证一定的抗压强度下,获得较好的发泡效果。同时,粉煤灰和疏浚淤泥的复掺在一定程度上可以提升泡沫混凝土的抗压强度。

螺旋推进式含油污泥清淤装置的设计与应用

目前油气田站场含油污泥清淤普遍采用人工加传统机械的办法,清掏困难、清淤效果不稳定且安全隐患突出。针对这一问题,设计了一种适合油田污油泥特点、主体功能集成、集装箱式可移动的含油污泥清淤装置,主要由移动式水下作业端、地面动力及控制工作站、连接管路、控制线缆组成。清淤系统采用旋转绞龙配合渣浆泵及高压水喷头的方式对淤泥进行收集;行走系统采用螺旋式推进结构,可在水下实现前后左右行进、原地旋转;控制系统包括地面控制台、电气控制柜以及水下作业端的动力液压控制仓,能够对装置进行全方位的控制与操作。各系统间相互配合,使其在能够行进过程中对所处位置的污油泥进行搅散、破碎、提取和输送等处理,绿色环保且为现场作业提供了极大便利。

河道疏浚技术在河道整治工程中的应用

我国地域辽阔、河流众多,形成了独特的河道生态系统。河道具有防洪排涝、灌溉航运等多种功能,而水土流失导致的河道淤积会使河道内的淤泥含量严重超标,不仅破坏了原有的河道生态环境,还严重影响了河岸居民的正常生产生活。为此,文章分析了河道疏浚技术在河道整治工程中发挥的重要作用,指明技术应用方向,阐述了河道疏浚技术在河道整治工程中的应用方法,旨在构建系统的河道疏浚技术体系,实现预期的河道整治目标。

Systematic assessment of dredged sludge dewaterability improvement with different organic polymers based on analytic hierarchy process

Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch(CS) and poly-dimethyl diallyl ammonium chloride(PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process(AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH_(4)^(+)-N and NO_(3)^(–)-N in the residual water. The increase of NH_(4)^(+)-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO_(3)^(-)-N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.

碱渣-矿渣固化疏浚淤泥含水率控制方法研究

以碱渣和矿渣为固化剂,电石渣为激发剂,通过设置不同含水率,碱渣、矿渣含量,开展固化疏浚淤泥的无侧限抗压强度和击实试验,以及核磁共振(NMR)、X射线衍射(XRD)和扫描电镜(SEM)测试,研究固化淤泥强度与含水率的关系。试验结果表明:固化淤泥强度随含水率的增加先增后减,可分为高强度段、强度急剧下降段和缓慢下降段,养护14 d时最高强度可达600 kPa以上。为使碱渣、矿渣高效地固化疏浚淤泥,可将含水率控制在淤泥塑限至液限之间,14 d强度不低于345 kPa。强度最优含水率与击实最优含水率相差不大,采用碾压法施工可将含水率控制在最优含水率的±3%范围,使固化淤泥强度处于高强度段;采用流动固化施工时,可根据强度要求,利用急剧下降段和缓慢下降段强度与混合含水率的幂函数公式确定含水率。

Effects of sludge dredging on the prevention and control of algae-caused black bloom in Taihu Lake,China

Algae-caused black bloom （also known as black water agglomerate） has recently become a critical problem in some Chinese lakes.It has been suggested that the occurrence of algae-caused black bloom was caused by the cooperation of nutrient-rich sediment with dead algae,and sludge dredging was adopted to control black bloom in some lakes of China.In this article,based on the simulation of black bloom using a Y-shape apparatus for modeling natural conditions,both un-dredged and dredged sites in three areas of Taihu Lake,China were studied to estimate the effects of dredging on the prevention and control of black bloom.During the experiment,drained algae were added to all six sites as an additional organic load;subsequently,the dissolved oxygen decreased rapidly,dropping to 0 mg/L at the sediment-water interface.Black bloom did not occur in the dredged sites of Moon Bay and Nan Quan,whereas all three un-dredged sites at Fudu Port,Moon Bay and Nan Quan experienced black bloom.Black bloom also occurred at the dredged site of Fudu Port one day later than at the other sites,and the odor and color were lighter than at the other locations.The color and odor of the black water mainly result from the presence of sulfides such as metal sulfides and hydrogen sulfide,among other chemicals,under reductive conditions.The color and odor of the water,together with the high concentrations of nutrients,were mainly caused by the decomposition of the algae and the presence of nutrient-rich sediment.Overall,the removal of the nutrient-rich sediment by dredging can prevent the occurrence and control the degree of algae-caused black bloom in Taihu Lake.

河湖生态清淤及淤泥固化一体化技术应用研究

淤泥固化是资源化处理的有效方法,河湖淤泥含水率高,强度低,含有有机质及污染物。目前以水泥为固化剂或者以水泥为主要成分的复合固化剂在河湖淤泥处理中使用较为普遍,但问题是能源消耗大、环境污染严重,而且固化土适应性差。生态清淤及淤泥固化一体化技术是一种环境友好型淤泥疏浚方法。工程案例证明,其专用固化剂能加快高含水率淤泥固化速度,能有效去除污染物,固化土能作为土工或建筑材料进行再生利用。