scholarly journals Strength and microstructure properties of solidified sewage sludge with two types of cement-based binders

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yijun Chen ◽  
Xingxing He ◽  
Shaohua Zhang ◽  
Xun Tan ◽  
Yong Wan
Keyword(s):  
Organic Matter ◽  
Sewage Sludge ◽  
Soft Soil ◽  
Microscopic Analysis ◽  
Hydration Product ◽  
Hydration Products ◽  
Early Hydration ◽  
Cementitious Binder ◽  
Before And After ◽  
Aluminate Cement

AbstractSolidification treatment with cementitious binder is an effective way to reduce environmental hazards of sewage sludge. Two cementitious binders, i.e., ordinary Portland cement (OPC) and sulfo-aluminate cement (SAC), were compared in this study to treat the sewage sludge. The strength of solidified sewage sludge (SSS) and changes in microscopic characteristics before and after treatment were analyzed through microscopic analysis methods. The effect of organic matter in sludge on the strength of SSS were also discussed. The results showed that the strength of SSS were lower than that of the solidified clay with no organic matter, and the filtrate extracted from the sludge can also weaken the cementation of the two cements significantly. The solidification effect of the OPC on the sludge was lower than that of the SAC evidently. The organic matter in the sewage sludge caused the surface of the soil particles to carry a large negative potential, which interfered with the hydration of the binder and reduced the amount of cementation skeleton formed by the binder hydration products. This resulted in a porous structure with low mechanical strength. The amount of early hydration product formed in the SAC-based solidified samples was higher than that of the OPC-based samples. This was favorable for filling the pores of the solidified samples and increasing their density. SAC had a better compatibility with soft soil containing high organic matter than OPC, and the which provides an effective alternative binder for dealing with sewage sludge.

scholarly journals The Influence of Water Reducing Agents on Early Hydration Property of Ferrite Aluminate Cement Paste

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 731
Author(s):  
Chunlong Huang ◽  
Zirui Cheng ◽  
Jihui Zhao ◽  
Yiren Wang ◽  
Jie Pang
Keyword(s):  
Setting Time ◽  
Critical Role ◽  
Hydration Product ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Hydration Process ◽  
Early Hydration ◽  
Cement Pastes ◽  
Hydration Rate ◽  
Aluminate Cement

The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.

Study on Optimization Proportioning Experiment and its Hydration Mechanism of Composite Cementing Material

2011 ◽  
Vol 121-126 ◽  
pp. 418-422
Author(s):  
Jin Xiao Liu ◽  
Zeng De Yin ◽  
Wen Bin Sun
Keyword(s):  
Portland Cement ◽  
Uniform Design ◽  
Material Strength ◽  
Filling Material ◽  
Hydration Products ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Cementing Material ◽  
Aluminate Cement

This article aims at the accelerating characteristic of coal filling material. We scientifically made a series of proportion on composite-cementing material through uniform design with Portland cement, sulpho-aluminate cement and gypsums. After having testing the capability of this, we found that some certain composite-cementing material strength has been improved, both early and later strength. Furthermore, we also continually analyzed the hydration products and microstructure of composite-cementing material, then determined that early hydration products were mostly ettringites and later were C-S-H-centered and CH-centered gel.

Effects of Polycarboxylate Superplasticizers on Hydration and Microstructure of Hardened Cement Paste

2012 ◽  
Vol 487 ◽  
pp. 692-696
Author(s):  
Rui Jun Gao ◽  
Sheng Hua Lv ◽  
Qiang Cao
Keyword(s):  
Calcium Carbonate ◽  
Cement Paste ◽  
Hydration Product ◽  
Ammonium Persulfate ◽  
Radical Copolymerization ◽  
Nucleation And Growth ◽  
Hardened Cement ◽  
Hydration Products ◽  
Hardened Cement Paste ◽  
Early Hydration

Polycarboxylate (PC) superplasticizer was synthesized by radical copolymerization using ammonium persulfate (APS) as initiator at 90 °C for 5 h. The effect of PC on the hydration process and microstructure of hardened cement at different hydration ages (4 h, 1 d and 7 d) was investigated. Hydration of cement paste results show that the nucleation and growth of hydration product of ettringite (Aft) was inhibited by PC at the early hydration ages, and the generation of the hydration products of calcium hydroxide (CH) and calcium carbonate (CaCO3) was promoted at late hydration ages. SEM result indicates that PC can make the structure of hardened cement more homogeneous and more density.

Sludge minimization by disintegration at different wastewater treatment plants

2008 ◽  
Vol 3 (1) ◽  
Author(s):  
Luchien Luning ◽  
Paul Roeleveld ◽  
Victor W.M. Claessen
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
New Technologies ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Biological Degradation ◽  
Ongoing Research ◽  
Sludge Minimization

In recent years new technologies have been developed to improve the biological degradation of sewage sludge by anaerobic digestion. The paper describes the results of a demonstration of ultrasonic disintegration on the Dutch Wastewater Treatment Plant (WWTP) Land van Cuijk. The effect on the degradation of organic matter is presented, together with the effect on the dewatering characteristics. Recommendations are presented for establishing research conditions in which the effect of sludge disintegration can be determined in a more direct way that is less sensitive to changing conditions in the operation of the WWTP. These recommendations have been implemented in the ongoing research in the Netherlands supported by the National Institute for wastewater research (STOWA).

Changes of some sewage sludge parameters prepared with an ultrasonic field

1997 ◽  
Vol 36 (11) ◽  
pp. 101-106 ◽  
Author(s):  
January Bien ◽  
Lidia Wolny
Keyword(s):  
Sewage Sludge ◽  
Microscopic Analysis ◽  
Chemical Compounds ◽  
Ultrasonic Field ◽  
Water Removal ◽  
Vacuum Filter ◽  
Additional Criterion ◽  
New Methods ◽  
Sludge Conditioning

Studies of sewage sludge conditioning by ultrasonic field concentrate on determination of the increase of water removal effect, which depends on kind of sludge and chemical compounds used in the dewatering process. An attempt was made to find new methods of sludge preparation before dewatering. Tests presented here focused on digested and difficult dewatered sludge. The sludge was dewatered on a vacuum filter after conditioning with polyelectrolytes and the ultrasonic field. The microscopic analysis was an additional criterion to evaluate changes in the sludge structure after preparation. The polyelectrolyte dose of 3 mg/g d.m. sonicated within 15 sec. resulted in the 50% decrease of sludge volume. Results presented confirmed our previous experiences, concerning the relation between conglomerates of sludge and the effect of dewatering.

scholarly journals Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil

2021 ◽  
Vol 13 (4) ◽  
pp. 2295
Author(s):  
Hailong Liu ◽  
Jiuye Zhao ◽  
Yu Wang ◽  
Nangai Yi ◽  
Chunyi Cui
Keyword(s):  
Soft Soil ◽  
Hydration Product ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Strength Performance ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
Stabilized Soil ◽  
Calcium Silicates ◽  
Hydrated Calcium

Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.

Environmental relevance of adsorption of doxycycline, enrofloxacin, and sulfamethoxypyridazine before and after the removal of organic matter from soils

2021 ◽  
Vol 287 ◽  
pp. 112354
Author(s):  
C. Alvarez-Esmorís ◽  
M. Conde-Cid ◽  
M.J. Fernández-Sanjurjo ◽  
A. Núñez-Delgado ◽  
E. Álvarez-Rodríguez ◽  
...  
Keyword(s):  
Organic Matter ◽  
Before And After ◽  
Environmental Relevance

scholarly journals Effect of Sewage Sludge Compost Usage on Corn and Faba Bean Growth, Carbon and Nitrogen Forms in Plants and Soil

Agronomy ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 628
Author(s):  
Hassan E. Abd Elsalam ◽  
Mohamed E. El- Sharnouby ◽  
Abdallah E. Mohamed ◽  
Bassem M. Raafat ◽  
Eman H. El-Gamal
Keyword(s):  
Organic Matter ◽  
Sewage Sludge ◽  
Plant Growth ◽  
Total Nitrogen ◽  
Faba Bean ◽  
Residual Effect ◽  
Growth Period ◽  
Nitrogen Forms ◽  
Amended Soils ◽  
Nitrogen Levels

Sewage sludge is an effective fertilizer in many soil types. When applied as an amendment, sludge introduces, in addition to organic matter, plant nutrients into the soil. When applied for cropland as a fertilizer, the mass loading of sewage sludge is customarily determined by inputs of N and/or P required to support optimal plant growth and a successful harvest. This study aims to examine the changes in organic matter contents and nitrogen forms in sludge-amended soils, as well as the growth of corn and faba bean plants. The main results indicated that there were higher responses to the corn and faba bean yields when sludge was added. Levels of organic carbon in soil were higher after maize harvest and decreased significantly after harvesting of beans, and were higher in sludge amended soils than unmodified soils, indicating the residual effect of sludge in soil. NO3−-N concentrations were generally higher in the soil after maize harvest than during the plant growth period, but this trend was not apparent in bean soil. The amounts of NH4+-N were close in the soil during the growth period or after the maize harvest, while they were higher in the soil after the bean harvest than they were during the growth period. Total nitrogen amounts were statistically higher in the soil during the growth period than those collected after the corn harvest, while they were approximately close in the bean soil. The total nitrogen amount in corn and bean leaves increased significantly in plants grown on modified sludge soil. There were no significant differences in the total nitrogen levels of the maize and beans planted on the treated soil.

Study on Mechanism of Removing the Organic Matter in Heavy Oil Sewage by the Electric Flocculation Method

2012 ◽  
Vol 535-537 ◽  
pp. 2201-2208
Author(s):  
Yong Wang ◽  
Jie Nian Jie ◽  
Zhi Yong Li ◽  
Li Guo Wang ◽  
Jiang Wu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Heavy Oil ◽  
Tin Dioxide ◽  
Electrochemical Treatment ◽  
Oily Wastewater ◽  
Treatment Technology ◽  
Before And After ◽  
Treatment Technologies ◽  
Oily Wastewater Treatment

Oily sewage is one of the wastes produced in the oil industry production process and its quantity has been increasing year by year, which influences the environment and human health severely. Electric flocculation method is one of the wide application electrochemical treatment technologies for the oily wastewater treatment at home and abroad, which has higher efficiency than other technologies at the aspect of the organic pollutants degradation. A simulative experiment device dealing with heavy oil sewage by the electric flocculation method has been designed in this paper. The mechanism of the electric flocculation method in removing organic matter of the heavy oil sewage by analyzing the change of the composition and content of the organic matter in water samples before and after the process of the electric flocculation has been studied. Research results show: the carbon/tin dioxide electrode is better than the carbon/ ruthenium dioxide electrode in removing organic matter; most alkanes matters in the oily wastewater have been removed in the dispersing oil form by the electric flocculation; as the current density increases, the types and quantity of the response organic matter can be improved while types of the new synthetic organics increase. At the same time, this paper provides a theory support in specific optimization of the electricity flocculation flotation in oily wastewater treatment technology and process.

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