Study on the effect of chitosan conditioning on sludge dewatering

2019 ◽  
Vol 79 (3) ◽  
pp. 501-509 ◽  
Author(s):  
Jin Zhang ◽  
Qing Hu ◽  
Jie Lu ◽  
Shuang Lin
Keyword(s):  
Moisture Content ◽  
Extracellular Polymeric Substances ◽  
Waste Water Treatment ◽  
Sewage Treatment ◽  
Organic Polymer ◽  
Sludge Dewatering ◽  
Sludge Treatment ◽  
Residual Sludge ◽  
Sludge Cake ◽  
Polymer Flocculant

Abstract The difficulty of residual sludge dehydration is the major problem in sewage treatment. The reduction of moisture content in sludge can reduce the sludge volume significantly and is conducive to the subsequent disposal of sludge. As an organic polymer flocculant, chitosan (CTS) is widely used in water and waste water treatment. In this study, CTS was used in sludge treatment to improve the sedimentation and dehydration properties of sludge. When treated with CTS, the moisture content of sludge cake decreased from 85.9% to 83.0%, the SV30 decreased to about 1/2, and the sludge volume reduced to 82.9%. Further analysis showed that the zeta potential (ζ-potential) of the sludge changed from negative value to positive value, and the D50 of the sludge was larger than that of the raw sludge. In addition, when the moisture content of the sludge cake was reduced to the lowest, the concentration of extracellular polymeric substances (EPS) and SCOD was the largest and the |ζ| decreased to the lowest. CTS improved the dehydration and sedimentation performance of sludge mainly by factors of electrical neutralization, adsorption bridging and dissolution of EPS.

Comparison of lime and alum as oily sludge conditioners

1997 ◽  
Vol 36 (12) ◽  
pp. 117-124 ◽  
Author(s):  
Tay Joo Hwa ◽  
S. Jeyaseelan
Keyword(s):  
Specific Resistance ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Oily Sludge ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Sludge Cake ◽  
Solids Content ◽  
Optimum Chemical

Chemical conditioning improves sludge dewatering. Choice of chemical conditioners is very much dependent on the characteristics of the sludges and the type of dewatering devices. Lime, alum, ferric chloride and polyelectrolytes are commonly used chemical conditioners. Anaerobic digested sludge samples collected from a sewage treatment plant with different oil contents varying from 1.8% to 8.0% by weight have been examined in the laboratory to find out their specific resistance, capillary suction time and filter yield. Lime and alum were used separately as conditioners. Different dosages of conditioner varying from 2% to 12% by weight were used to determine the optimum chemical dosage for varying oil contents. Lime dosages of about 6% were found to yield favourable characteristics. Addition of alum decreases the specific resistances and capillary suction times of oily sludges rapidly up to 4% dosages. Alum dosages beyond 4% only increase the solids content in the sludge cake and increase the sludge volume to be handled. A correlation between CST and specific resistance to filtration was established. CST can be measured easily and quickly in the laboratories. Using the CST and the correlation a quick prediction on dewaterability can be established.

Evaluation of Municipal Sludge Drying and Dewatering with Respect to Sludge Volume Reduction

1990 ◽  
Vol 22 (12) ◽  
pp. 153-161 ◽  
Author(s):  
Maryla Smollen
Keyword(s):  
Moisture Content ◽  
Treatment Strategies ◽  
Vacuum Drying ◽  
Municipal Sludge ◽  
Moisture Retention ◽  
Sludge Dewatering ◽  
Sludge Treatment ◽  
Energy Inputs ◽  
Retention Characteristics ◽  
Sludge Drying

A number of parameters that influence sludge dewatering behaviour have been identified, but there is a lack of consensus which of these are of the greatest concern in sludge treatment strategies. Moisture retention characteristics were obtained from vacuum drying of centrifuged sludge samples to subdivide moisture into immobilised, physically and chemically bound fractions. Physically bound moisture is responsible for unsatisfactory dewatering by centrifugation. Polyelectrolyte releases some of the immobilised water, but simultaneously increases the physically bound moisture content which gives rise to large energy inputs during mechanical dewatering. Commonly used dewaterability measurements do not appear to be linked to moisture retention characteristics.

Toxicity assays and their evaluation on organic polymer flocculants used for municipal sludge dewatering

1998 ◽  
Vol 38 (7) ◽  
pp. 207-215 ◽  
Author(s):  
H. Takigami ◽  
N. Taniguchi ◽  
Y. Shimizu ◽  
S. Matsui
Keyword(s):  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Algal Growth ◽  
Pilot Scale ◽  
Organic Polymer ◽  
Municipal Sludge ◽  
Sludge Dewatering ◽  
Algal Toxicity ◽  
Reproduction Tests

The toxicity of organic polymer flocculants used for the dewatering of municipal sludge was evaluated by using two different toxicity assays: the Closterium ehrenbergii algal toxicity test and the Bacillus subtilis rec-assay. The algal toxicity of the effluents from a pilot-scale sewage treatment plant was investigated with and without the addition of a flocculant (0, 0.05, 0.10 and 0.20 mg/L). No clear evidence on the toxicity caused by the flocculant was observed on both asexual and sexual reproduction tests of C. ehrenbergii. It was also found that the algal growth inhibition of various types of flocculants (i.e., cationic, anionic, amphoionic and non-ionic) was in the order of 1 to 20 mg/L, which was mainly due to a molecular weight (MW) fraction of greater than 100,000. The results of the B. subtilis rec-assay for these flocculants indicated that eight out of ten cationic flocculants caused the direct DNA damage with LC50 =0.1 to 10 mg/L. One of the genotoxic flocculants was also fractionated into their components by MW. The experimental results showed that the lethal effects were mainly contributed by the polymer fraction of MW greater than 100,000, although the genotoxicity was not detected in that fraction. Therefore, the detected genotoxicity of the flocculants could be caused by the combined effects of various components, such as polymers, oligomers, monomers and additives.

Enhancing paper sludge dewatering by waste polyester fiber and FeCl3 for preparation of Fe-rich biochar

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 2326-2345
Author(s):  
Xin Zhang ◽  
Guolin Tong ◽  
Yiheng Zhou ◽  
Guoyi Li ◽  
Hui Zhang
Keyword(s):  
Extracellular Polymeric Substances ◽  
Catalytic Effect ◽  
Paper Sludge ◽  
Sludge Dewatering ◽  
Filtration Resistance ◽  
Sludge Recycling ◽  
Sludge Cake ◽  
Polyester Textile ◽  
Floc Strength ◽  
Sludge Dewaterability

The paper sludge conditioning effects of waste polyester textile fibers as skeleton builders combined with ferric chloride (FeCl3) were evaluated and the sludge dewatering mechanism was explored. The catalytic effect of Fe-rich sludge biochar (Fe-SB) on enhancing sludge dewaterability was evaluated. Results showed the combined fiber-FeCl3 conditioning significantly promoted the sludge dewaterability compared with conditioner alone, leading to a 77.5% decrease in specific filtration resistance and a 68.9% increase in net yield. The decrease of extracellular polymeric substances (EPS) contents showed that the EPS were difficult to extract and sludge floc strength was enhanced as a result of chemical reactions such as complexation processes and charge neutralization. Hence, the enhancement of sludge dewaterability was primarily due to the sludge cake with a porous and incompressible structure formed by fiber and FeCl3, and the rigidity structure of fiber. Moreover, the Fe-SB prepared by fiber-FeCl3 conditioning sludge could effectively activate persulfate to enhance the sludge dewaterability, with water content of dewatered sludge decreasing by 14.6%. The Fe-SB had dual functions of the heterogeneous catalyst of persulfate and skeleton builder. This study presents a sludge recycling method that combined physicochemical conditioning and sludge biochar materials prepared by pyrolysis.

A New Sensing Technique for Optimum Sludge Conditioning for Waste Sludge Dewatering

1993 ◽  
Vol 28 (11-12) ◽  
pp. 481-488 ◽  
Author(s):  
Y. Yasukawa ◽  
T. Totoki ◽  
H. Shigemi
Keyword(s):  
Moisture Content ◽  
Laboratory Test ◽  
Sludge Dewatering ◽  
Film Sensor ◽  
Waste Sludge ◽  
Sludge Cake ◽  
Sludge Dewaterability ◽  
Sludge Conditioning ◽  
Hot Film ◽  
Hot Film Sensor

A new sensing technique using a Hot-Film sensor for determining the optimum polymer dosage for sludge dewatering has been developed. Correlations between the behavior of the Hot-Film sensor and dewaterability of sewage and night soil sludge were investigated. The results of the study revealed the following: the Hot-Film sensor values depended on the filtrate characteristics related to the sludge dewaterability which is measured by the filterability of the conditioned sludge and by the moisture content of the dewatered sludge cake; the optimum polymer dosage for sludge dewatering corresponded with the minimum output value on the characteristics curve of the Hot-Film sensor. This paper describes the observations of the measurement test by the Hot-Film sensor as well as the results of the laboratory test of sludge dewatering for optimum sludge conditioning.

Freeze–thaw combined with activated carbon improves electrochemical dewaterability of sludge: Analysis of sludge floc structure and dewatering mechanism

2021 ◽  
Author(s):  
Kai Hui ◽  
Lei Song ◽  
Zhenzhou Yin ◽  
Hongwei Song ◽  
Zehao Wang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Extracellular Polymeric Substances ◽  
Combined Treatment ◽  
Electrochemical Treatment ◽  
Sludge Dewatering ◽  
Element Analysis ◽  
Sludge Flocs ◽  
Freeze Thaw ◽  
Floc Structure ◽  
Sludge Cake

Abstract Freeze–thaw (F/T) and electrochemistry are environment-friendly and efficient sludge treatment technologies. In this study, F/T and electrochemistry were combined in the pretreatment of sludge dewatering in the laboratory, and activated carbon (AC) was added to improve the electrochemical dewatering performance of sludge. During the experiment, the effect of F/T on the floc structure was analyzed by a laser particle analyzer and scanning electron microscope. F/T treatment not only improved the dewatering performance of sludge, but also promoted the aggregation of sludge flocs into larger particles. The median diameter (D50) increased from 45.27 µm to 128.94 µm. Then, the intracellular polymer of large-particle sludge was analyzed by three-dimensional excitation–emission matrix (3D-EEM). The tightly bound extracellular polymeric substances (TB-EPS) still contained a large amount of protein substances, which hindered the improvement of sludge dewatering performance. AC was added to the thawed sludge solution before electrochemical treatment (EP). The conductivity of AC enhanced the effect of EP, thereby cracking the sludge flocs. Thus, the light intensity of TB-EPS in the 3D-EEM fluorescence spectroscopy was decreased, and the D50 was also reduced to 105.3 µm. The final specific resistance of filtration and water content were reduced by 96.39% and 32.17%, respectively. Element analysis of the sludge cake after dehydration showed that the addition of AC significantly improved the combustion efficiency of the sludge cake. Moreover, preliminary economic analysis showed that the cost of this research was low, which indicated the potential application value of combined treatment.

scholarly journals Effects of Moringa Peregrina and Ferric Chloride (FeClƒ ) On Water Treatment Sludge Dewatering

2018 ◽  
Vol 15 (4) ◽  
pp. 975-980 ◽  
Author(s):  
Ramtin Mazaheri ◽  
Mostafa Tizghadam Ghazani ◽  
Abolghasem Alighardashi
Keyword(s):  
Water Treatment ◽  
Moisture Content ◽  
Ferric Chloride ◽  
Optimum Dose ◽  
Water Treatment Sludge ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Cake Moisture ◽  
Sludge Cake ◽  
Conditioning Effect

In the present study, an active component of Moringa peregrine (MP) was used in comparison with ferric chloride (FeCl₃) for the conditioning of water treatment sludge. The comparison was based on dewatering characteristics of the conditioned sludge determined by capillary suction time (CST), specific resistance to filtration (SRF), tests of time of filtration (TTF) and sludge cake moisture content. The results indicated that MP showed relatively comparable conditioning effect as ferric chloride. Sludge conditioned with ferric chloride, showed better results than MP. According to CST, SRF and tests of time of filtration (TTF) and sludge cake moisture content results, optimum dose for MP, and ferric chloride was 100 ml/l. From the results of the study it could be concluded that MP alone could be effectively used and replace ferric chloride for dewatering of water treatment sludge.

scholarly journals Feasibility Study of Shell Powder as Sludge Conditioning Agent

2020 ◽  
Vol 194 ◽  
pp. 04016
Author(s):  
Zhongwei Zhang ◽  
Yubo Cui ◽  
Junwen Ma ◽  
Wanjun Zhang ◽  
Zhaobo Chen
Keyword(s):  
Moisture Content ◽  
Ph Value ◽  
Specific Resistance ◽  
Dry Weight ◽  
Optimal Dosage ◽  
Sludge Dewatering ◽  
Sludge Treatment ◽  
Ph Values ◽  
Sludge Conditioning ◽  
Shell Powder

Sludge becomes a “world problem” with the increase of wastewater treatment amounts across the world. Sludge treatment is mainly for reduction, stabilization, harmlessness and recycling. By adding sludge conditioning agents, it can effectively reduce the moisture content and the specific resistance of sludge, and provide effective guarantees for subsequent sludge dewatering. The shells were used to reduce the moisture content and specific resistance of sludge herein. Through the analysis of experimental data, the results showed that the best dosage of shell powder solution was 6% of the dry weight of the sludge, and the best dosage of shell powder was 24% of the dry weight of the sludge. Under the optimal dosage, changing the pH value could also cause changes in the water content and the specific resistance of the sludge. The optimal pH values of the shell powder solution and shell powder for sludge conditioning were 8-9 and 7, respectively.

Технологические аспекты обезвоживания осадков промышленно-дождевых сточных вод автотранспортных предприятий

2019 ◽  
pp. 25-30
Author(s):  
G. Variushina
Keyword(s):  
Wastewater Treatment ◽  
Moisture Content ◽  
Vacuum Filter ◽  
Operational Parameters ◽  
Technological Parameters ◽  
Wastewater Treatment Process ◽  
Motor Transport ◽  
Cationic Flocculant ◽  
Residual Sludge ◽  
Treatment Facilities

Приводятся сведения об условиях формирования, объемах, химическом составе и свойствах осадков очистных сооружений производственных сточных вод автотранспортных предприятий. Даны примеры технологических решений по обезвоживанию образующихся в процессе очистки шламов. Рассмотрены технологические аспекты процесса интенсификации механического обезвоживания уплотненных осадков с использованием высокомолекулярных полиэлектролитов. Представлены данные лабораторных экспериментов по выбору типа флокулянта, его дозы, технологических параметров процесса, а также результаты определения влажности обезвоженных осадков, полученные на модели барабанного вакуум-фильтра. Приведены примеры эффективных обезвоживающих аппаратов отечественного производства и их технические характеристики, рекомендации и критерии их выбора, а также факторы, оказывающие влияние на эксплуатационные параметры обезвоживающего оборудования. Установлено, что наилучшая обезвоживающая способность барабанных вакуум-фильтров (остаточная влажность шламов от 66 до 83) может быть достигнута при применении катионного флокулянта ВПК-402 для осадков различных производственных цехов автотранспортного предприятия.Information on the conditions of generation, volumes, chemical composition and properties of sludge generated at the industrial wastewater treatment facilities of motor transport enterprises is provided. Examples of process engineering solutions for dewatering sludge generated during the wastewater treatment process are given. The technological aspects of enhancing mechanical dewatering of thickened sludge using high-molecular polyelectrolytes are considered. The data of laboratory experiments on choosing the type of flocculant, its dose, technological parameters of the process, as well as the results of determining the moisture content of dewatered sludge obtained in a model of a drum vacuum filter are presented. Examples of effective domestically produced dewatering apparatus and their technical characteristics, recommendations and criteria for their selection, as well as factors influencing the operational parameters of the dewatering equipment are given. It is found that the highest dewatering capacity of drum vacuum filters (residual sludge moisture content from 66 to 83) can be achieved by using VPK-402 cationic flocculant for processing sludge generated at the workshop premises of a motor transport enterprise.

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