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Energy use, together with consumption of raw materials, machine clothing, and wet end chemicals, are some of the most critical aspects in successful tissue making today. This work was aimed at developing a laboratory-scale method of estimating dewatering mechanisms, vacuum efficiency, and energy use of Through Air Drying (TAD) of tissue. When compared to pilot data, the results of the new laboratory method for investigating dewatering during TAD were in the same magnitude, around 24 to 26% dryness after vacuum dewatering, and 27 to 29% dryness after TAD molding. Sheet properties, such as caliper and surface profile, were evaluated and compared to commercial tissue sheets. The results indicate that it will be possible to precisely measure accurate dryness development and penetrated air volume for tissue sheet forming and TAD molding at a laboratory scale. This can contribute to the efforts of implementing a circular forest-based bioeconomy by increasing the fundamental understanding of dewatering of tissue paper materials, which is facilitated by improvements in energy use. The new method developed in this work will make it easier to assess ideas that are difficult to bring to pilot scale or full scale before learning more of the dewatering capabilities. The authors are convinced that improved knowledge of tissue dewatering mechanisms, forming, and material transport during and after TAD dewatering can increase the efficiency of the industrial manufacturing processes.

Technological comparison and system modelling of sewage sludge treatment are important in terms of sustainable development and climate change mitigation. Dewatering and drying are important processes for reducing volume for transportation and often a requirement for further sludge treatment. Inventory data on mass transfers and material and energy consumptions are therefore crucial in improving and understanding sludge management systems. Reviewing the scientific literature (2003–2021) revealed 55 and 21 datasets on dewatering and drying of sewage sludge, respectively. The scarcity of data did not allow for identifying detailed relationships between inputs and outputs for the technologies, but the reviewed data can serve as the first port of call when planning sludge management. The average total solid (TS) content obtained was statistically different for mechanical dewatering (MDW), deep dewatering, bio-drying (BDR) and thermal drying (TDR). Loss of volatile solids (VS) during dewatering is barely described, but a substantial VS loss was observed for TDR (8%) and BDR (27%). The use of chemical agents in MDW showed typical values of 5–15 g kg−1 TS. The use of energy is low for MDW (average of 0.12 and 0.26 kWh kg−1 TS for raw and digested sludges, respectively) but substantially higher for TDR (average of 3.8 kWh kg−1 TS). The justified inventory data for sludge dewatering and drying provide essential support to system modelling and technological comparison in future studies, but additional data from full-scale plants on energy consumption and the composition of removed water are strongly requested to improve the inventory.

Geotextile tube dewatering is a pre-treatment method utilized in the remediation of high-water content materials (i.e. sediments and slurries). However, given the association some contaminants (e.g. dioxins and furans, (i.e. PCDD/F)) have with particulate matter in these contaminated sediments, understanding the fate and transport of this particle matter in the dewatered effluent is essential. In this paper, pressure filtration tests (PFTs) were conducted to investigate the effect of pressure and filter cake formation on both geotextile filtration efficiency and effluent quality. Transport tests were then performed to evaluate the particle transport through the developed filter cake, as well as the hydraulic characteristics of the medium during dewatering. HYDRUS, a one-dimensional model contaminant transport model was then employed to simulate the experimental particle transport test results. Three different mechanisms of particle transport (i.e. attachment only, detachment only, both attachment and detachment) through saturated porous media were examined to identify the possible mechanisms of observed effluent particle concentration. HYDRUS modeling outputs suggest that both attachment and detachment mechanisms are involved in a given particle's fate and transport during geotextile dewatering. In addition, parameters such as confining pressure and filter cake properties affect the particle concentration in the effluent.

The ability of cationized dialdehyde cellulose to improve the mechanical properties of paper was evaluated. The majority of cationized additives are synthesized by introducing cationic groups through chemical reactions. Here, cationized additives were produced in a more environmentally friendly manner by use of non-toxic and readily biodegradable deep eutectic-like solvent mixtures (DESs). The modified cellulose’s properties were characterized by FTIR, polarized-light optical microscopy, charge titrations, and SEM/EDX. The cationized additives were investigated as strength additives for papermaking. Three different amounts of cationic additive (2%, 5%, and 10%) were added to the pulp, and the properties of handsheets were studied. Because increasing the additive content can affect dewatering of the process, the dewatering capabilities of the pulps with additives were evaluated by Schopper-Riegler (°SR) value, water retention value (WRV), and vacuum dewatering. Finally, the recyclability of the DES was assessed in terms of cationization reaction efficiency and their effect on paper mechanical properties.

Coconut shell is a bio-waste, and its availability is high to waste in the coastal region of Karnataka, India. The present study focused on using coconut shell biochar modified with ferric chloride to enhance the sludge dewaterability, and it is evaluated experimentally (Capillary suction time, moisture content, settleability, zeta potential, heavy metals, and phosphate). Further, scanning electron microscopy, Fourier transformation infrared spectroscopy, and X-ray diffraction characterization were carried out to identify the structure's change. A significant reduction in capillary suction time (56 s) and the moisture content (96.5%) of the dewatered sludge cake was obtained. Sludge dewatering using coconut shell biochar modified with ferric chloride was optimized by a Box Behnken method with three main factors including dosage, rapid mixing time, and slow mixing time. Optimum capillary suction time (55.6 s) was achieved at coconut shell biochar modified with ferric chloride dosage (41% dry solids), rapid mixing time (10 min), and slow mixing time (19 min). The significant structural change in sludge particles was confirmed through characterization studies. During the dewatering process, the removal of heavy metal (cadmium, chromium, lead, and nickel) and phosphate (50.6%) was evident. Hence attempt of coconut shell biochar modified with ferric chloride as a skeleton material is an economical and promising option for sludge dewatering.

For a deep excavation in sandy cobble stratum, the loss of fine sand particles caused by dewatering generally leads to ground settlement. This paper first analyzed the rules of land subsidence caus...

The increase of electrical resistance (ER) and energy consumption (EC) during the later stage of dewatering is a major problem hindering the development of electro-dewatering (EDW) technology. As the variations of sludge characteristics are significant during the EDW process, the relationships between sludge characteristics and ER and EC during EDW remain unclear. In this study, the effects of moisture content (MC), thickness, pH, conductivity, zeta potential, temperature, and gas volume on the ER and EC during the EDW process were statistically investigated using correlation and multiple linear regression analyses. Herein, the results showed that the ER of the sludge near the anode was primarily affected by pH, whereas the sludge near the cathode was primarily affected by the MC and conductivity. Further, sludge temperature and conductivity were the most reliable indicators to predict the EC near the anode and cathode, respectively. The results of this study provide theoretical guidance useful for solving the increase of ER and EC during the later stage of the EDW process.

Dewatering of alum sludge from drinking-water plants is proving to be a major challenge because of the large amounts of residual sludges produced annually. In the last few years, most studies have focused on improving the dewatering process to reduce costs of alum sludge management and transport. In the present study, three different types of conditioners were tested. Lime was used as an example of an inorganic conditioner, ferric chloride (FeCl3) was used as an example of a chemical conditioner and chitosan was used as an example of a biopolymer. The performance of a conditioner was evaluated with respect to its effect in reducing the resistance of the conditioned sludge to filtration, namely the specific resistance to filtration (SRF). Tests are run using different concentrations of the conditioners, different speeds of rotation and different pH values to investigate the maximum value of percentage reduction in SRF. The response surface methodology was chosen from the Design-Expert program (version 12), and the Box–Behnken design was employed to find factor settings that optimise the output response – that was, percentage reduction in SRF (Red. %). The model obtained proved to be significant enough but with varying degrees. Chitosan showed to be the most favourable conditioner with a maximum percentage reduction in SRF of 98.57%. This was followed by ferric chloride, which gave a value of 89.2% for percentage reduction in SRF, and lastly came lime with a percentage reduction of 79.81%. Besides, a lower concentration of the conditioner and a lower speed of rotation are required when using chitosan as a conditioner.

In this study, the conditioning effect of cationic polyacrylamide (CPAM) with different charge densities on raw sludge (RS) and thermo-hydrolyzed sludge (HS) pretreated with or without ferric salt is studied through orthogonal experiments. In addition, this paper uses the principles of rheology and morphology to analyze and clarify the conditioning mechanism of RS and HS, and reveals the mechanism of thermal hydrolysis to improve the dewatering performance of sludge. Compared with the RS, the HS has smaller particle size, better filterability, stronger fluidity and more obvious thixotropy. However, due to the influence of filter pressing time, ferric salt should be added before conditioning. The orthogonal experiment shows that the optimal conditioner is CPAM with charge density of 60, and the specific resistance to filtration and capillary suction time of the adjusted thermo-hydrolyzed sludge are reduced to (1.11 ± 0.07) × 1012 m/kg and 16.1 ± 1.8 s; the particle size increased from 61.2 to 253.5 μm. The moisture content of the sludge cake is about 48%. The structural strength and thixotropy of HS are higher than those of the RS, and can be greatly improved by adding ferric salt. Morphological analysis confirms that thermal hydrolysis can lyse microbial cells in sludge, and the sludge treated with ferric salt will have more porous structure and stronger flocculation strength. HIGHLIGHTS Effects of CPAM on conditioning of raw sludge and thermal hydrolysis sludge were studied.; Thermal hydrolysis treatment will improve sludge dewatering capacity and fluidity.; Ferric salt treatment enhanced structural strength and thixotropy of conditioned thermal hydrolysis sludge.; Rheological analysis can be used as a new tool to reflect the dewatering capacity of sludge.

Dewatering of sludge is a key problem that must be solved in the sewage sludge disposal industry. In this study, a series of process optimization tests were conducted to learn how to improve sludge treatment. The optimum process of sludge leaching treatment was studied in a specially designed 100-L reactor system. Four factors were investigated and nine batches of bioleaching tests were run at three levels of these factors. Orthogonal experiments showed that the effect of sludge return ratio and aeration rate on the sludge moisture content was significant and hydraulic retention time (HRT) had a clear effect, but nutrient types had a reduced effect on the moisture content of sludge. The primary and secondary order of each factor is reflux ratio > aeration rate > HRT > nutrient type. Under the optimal process, three batches of sludge were processed and the moisture content of the filter press cake was reduced to less than 60%, the organic matter content reduced to below 5%, and the concentration of heavy metals (Cu, Zn, Pb, and Cr) was much lower than the agricultural standard limit, which is suitable for landscaping, composting, and incineration power generation and other resource applications.

Mechanical dewatering and thermal techniques were evaluated as pre-treatment steps to reduce the water content of spent coffee ground (SCG) powders to thermal conversion. An exploratory evaluation of the fluid dynamic patterns in fluidization of wet SCG powders showed that stable fluidized regimes were achieved with powders of moisture levels under 50 %. Mechanical dewatering was effective to reduce the powder moisture content to 45 %. Adding vibration enhanced the powder feed rate in the drying bed, even for powders with moisture levels that lead to negligible cohesiveness. Using a dimensionless vibration number Γ = 4 with different vibration amplitudes (A = 0.015 and 0.003 m) resulted in different dynamic behaviors and influenced the solids feeding rate but did not affect the mean Sauter diameter of the elutriated powder. Thermal drying at Γ = 4 and A = 0.015 m allowed a steady and continuous operating regime for powder production. Under these vibration parameters, the optimum condition concerning moisture content (22 % w.b.) and mean particle size (0.37 mm) was predicted to occur at 70 °C, and U/Umf = 6. The dry powder was thermally characterized and confirmed the feasibility of using this residue in pyrolysis and combustion processes. The parameters of the reaction kinetic model and the apparent specific heat were obtained.

A field sampling programme was undertaken to assess the variability of physical characteristics of contaminated sediments in a large (160 ha) effluent stabilisation lagoon. The objective of this pa...

Foams were prepared from hydrophobically modified ethyl(hydroxyethyl) cellulose (EHEC), methyl nanocellulose, and native microfibrillated cellulose (MFC). Their film- and foam-forming abilities, stabilities, and suitabilities for foam coating on different substrates were investigated. The role of EHEC as a polymeric stabilizing agent was also studied. The EHEC-MFC foams showed greater stability and water-holding ability under pressurized dewatering than MFC foams prepared in the presence of a surfactant. A foam could be created with methyl nanocellulose without any foaming agent. Selected nanocellulose gels and foam formulations were used to coat various substrates. The surface was efficiently closed by gel and foam coatings prepared from the methyl nanocellulose and EHEC solutions, which was ascribed to good coating holdout. Coatings on papers with different levels of smoothness/density and hydrophobicity/ hydrophilicity confirmed that foam-substrate interactions affected the coat quality. The air permeance was reduced by 99% and 64% with a methyl nanocellulose coating and an EHEC-MFC coating, respectively. An EHEC-MFC coating created a hydrophobic surface on a hydrophilic substrate, and methyl nanocellulose improved the oil resistance even at a low coat weight.

The high energy consumption of the microalgae dewatering process results in microalgae being less economically feasible as a new bioenergy material. As an energy-saving method, forward osmosis (FO) filtration can be applied in microalgae dewatering to reduce membrane fouling and energy consumption. In this study, a novel hybrid dead-end/cross-flow FO system was proposed to obtain highly efficient microalgae dewatering. The effects of agitation speed, draw solution concentration, and pH on microalgae and membrane flux reduction volume concentration factors were investigated using Box-Behnken design (BBD) of response surface methodology (three factors and three levels). The results demonstrated that the higher the draw solution concentration and agitation speed, the higher the volume concentration factors. When the draw solution concentration and agitation speed reached their maximums (5 M and 500 r, respectively), the maximum volume concentration factor was obtained (3.73). pH exhibited the greatest influence on flux reduction. The flux reduction decreased more with an increase in pH (pH > 7). When the pH was neutral or acidic, the influence of pH on flux was insignificant. This study provided a more efficient method for dewatering and reduced energy consumption by applying a BBD to optimize the operation parameters of a novel hybrid dead-end/cross-flow FO system for microalgae dewatering.

The mechanical dehydration method is generally used for reducing the moisture content in sludge. However, there is little understanding of the physical and mechanical properties and dehydration mechanism of sludge during pressurization. In this paper, characteristics of sludge were studied from the perspective of soil mechanics. The water permeability, loading conditions, and dehydration performance of the sludge during the pressurization process were analyzed through a series of geotechnical laboratory experiments. The results showed that the pore structure, compressibility coefficient, consolidation coefficient, and permeability coefficient of the sludge are related to the dehydration rate. The conditioners that mixed with sludge could increase the dewatering rate by reducing the sludge viscosity, changing the water status, and increasing the permeability coefficient. The two conditioners used in this study increased the dehydration rate of the sludge from 27.5 to 52.6% and 63.9%, respectively. Unlike the seepage consolidation of ordinary clay, which has only one stage, the seepage consolidation of sludge could be divided into three stages. The removed water in the first stage is mainly free water; the discharge in the second stage is the combination of free water and bound water, and bound water was mainly discharged in the third stage. The water content at the end of each stage corresponds to the liquid limit, plastic limit, and shrinkage limit of the sludge. Our study provides a novel insight for understanding the deep dewatering of sludge and is benefit to solve the problem of sludge dewatering.

Geotextile tubes (geotubes) filled with lightly Cement-Mixed Soil (CMS) are used to construct a containment bund. The proposed containment bund was made of three layers of geotextile tubes, where each of the geotube was infilled to a height of 2m and stacked to form a 6m high containment bund in the shape of a triangular prism. Three geotubes were placed side by side to form the first layer of the containment bund. The shear strength development of the CMS of the first layer containment bund was evaluated using a modified mini Cone Penetration Test (CPT) after the infilling. The results suggested that the shear strength developed in the centre geotube is generally lower than the edge geotubes. It was hypothesised that the edge geotubes, which were installed before the centre geotube, hindered the dewatering action of the centre geotube during its infilling process. Hence, a study on a scaled-down version of the three geotubes arrangement was conducted in the field with instrumentation. The hypothesis mentioned above was examined through the changes in volume and strain mobilised in the geotextile of geotube, the dewatering rate, and the shear strength development of the CMS, pore pressure and total pressure changes during infilling and dewatering phase of the geotubes. The study showed that the construction sequence of the geotubes indeed affects the shear strength development of the CMS.

Flocculant played an important role in water treatment and sludge dewatering. It is imperative to design and synthesize an eco-friendly and biodegradable flocculant based on natural polymer. In the present work, a new amphoteric CMC-based flocculant, CMC-g-PDMC was synthesized via grafting DMC onto hydroxyl of CMC initiated by potassium persulfate under traditional heating condition. The optimal graft copolymerization condition was optimized by orthogonal experiment. The structure, morphology and thermostability of the obtained graft copolymer were characterized by measuring FT-IR, XRD, SEM and TGA analyzer, respectively. Moreover, comparing with the commercial flocculant PAM, PAC and CPAM, the dewatering capacity of municipal sludge was evaluated using CMC-g-PDMC by FCMC, SRF, SVI and light transmittance. It suggested that the flocculation to municipal sludge was related to the ion properties of the flocculant.

Sludge dewatering is an important step for wastewater treatment. Composite degradable flocculant (CDF) was prepared by cationic polyacrylamide (PAM) grafting onto modified starch with a novel initiator, and characterized by Fourier transform infrared spectroscopy. The microstructure of flocculated sludge was characterized by scanning electron microscopy. The study investigated the properties of CDF compared to PAM, which showed that the prepared CDF exhibited a highly effective flocculation on sludge dewatering, a higher transmittance and chemical oxygen demand removal rate, and a lower value of effluent ammonia nitrogen and total phosphorus. The fermentation process was also analyzed by testing the performance of dewatered sludge (temperature, pH, ammonia nitrogen, E4/E6 (humic acid absorbance at 465 nm (E4) and 665 nm (E6))). The dehydrated sludge with CDF could be easily compressed into cakes by belt-filter for easy transportation and storage. With the continuous addition of CDF and PAM, the corresponding index of capillary suction time (CST) increased. Moreover, the total value of CST with CDF was low, showing a good dewaterability. In addition, the sludge index of pumping time and moisture content with CDF were low in contrast with PAM. Fermentation experiments demonstrated that sludge with CDF had a comparatively high temperature and low value of E4/E6. Such novel CDF shows enormous potential in wastewater treatment and sludge fermentation.

Most studies on the impact of reject waters recycled from sludge processing in the multi-phase activated sludge process focus on anaerobic sludge treatment in large wastewater treatment plants, leaving apart the processes of aerobic sludge stabilization often used in smaller facilities in rural and suburban areas. The article presents the results of tests carried out in three small and medium-sized wastewater treatment plants with biological removal of biogenic compounds that use aerobic stabilization to process sludge. The research concerned the quantity and quality of reject waters generated in the process of aerobic stabilization and dewatering of sewage sludge and their impact on the multi-phase activated sludge process. The results showed that the average volume of generated reject waters ranged from 3.2 to 5% of the incoming wastewater volume. The average share of organic compounds and total nitrogen loads contained in reject waters did not usually exceed 5–10% of the loads in raw wastewater but reached almost 50% in the case of total phosphorus. Studies indicated that the composition of the supernatant from aerobic stabilization is strongly dependent on the course of the process. The best quality was obtained for cyclic operation of the aerobic stabilization tank with 16 h of aeration and 8 h of settling. The results also showed the negative impact of sudden discharges of reject waters from sludge processing to a multi-phase biological reactor, which can be reduced by using an appropriate equalization tank and pretreatment of the side stream to reduce the recirculation of phosphorus.

Coastal cities in the UAE lie on a flat terrain created by tidal inundation and with super-saline groundwater within a few metres of the ground surface. Construction requires almost always dewatering in order to allow activities to proceed in dry conditions. Due to the tidal environment, the proper conceptual and numerical model for dewatering that applies to coastal UAE locations is transient, radial flow to pumping wells in an unconfined aquifer. This work utilises two numerical codes to study flow conditions at a Dubai site. The value of the radial hydraulic conductivity was found to be consistent with the site’s geologic description and falls in the middle of the range of values for the observed horizontal hydraulic conductivities. The vertical hydraulic conductivity was representative of a silty-type material and was consistent with the value estimated through packer tests approximately in the middle of the saturated thickness.

Wastewater treatment plants are one of the major routes transporting emerging contaminants (ECs) to the water environment. Mathematical modelling is an essential tool to assess the fate of ECs through wastewater treatment. In the context of this study, a plant-wide mathematical model was developed and calibrated. According to the results, the dominant removal mechanisms have been identified for each target compound, thus confirming previously published data on their physicochemical properties. Solids retention time is an important operating parameter which highly influences the removal rate of most biodegradable ECs, while the performance of primary sedimentation, with regard to solids removal, influences the fate of both soluble and particulate fraction of ECs. Furthermore, the increase of solids capture rate in sludge thickening and dewatering units is associated with a decrease in ECs removal rate and their content in biomass. The hourly fluctuations in the inflow loads of ECs result in a variation of effluent ECs concentration with the same periodicity but with a significantly lower range.

Sewage sludge disposal and utilization have become an ever-increasing challenge due to the rapid development of urbanization and strict environmental protection requirements in China. Incineration is becoming one of the most important strategies for sludge disposal due to the large volume reduction rate, destruction of contaminations, and energy recovery. A general introduction to sludge disposal status in China will be summarized, including sludge production, characteristics of sludge, and existing disposal methods. Second, current research and developments regarding the whole process of sludge incineration will be introduced, which consist of the pretreatment of sewage sludge (e.g., thickening, conditioning, dewatering, and drying), incineration (e.g., co-combustion and mono-combustion), and pollutant control (e.g., gaseous pollutant, heavy metals, and fly ash). Different kinds of incinerators performing sludge mono- or co-combustion are thoroughly introduced and analyzed. Finally, several typical commercial applications of sludge incineration, including the key operation parameters, will be discussed in detail to illustrate the development of the sludge incineration technique in China.

Coal mining by PT. Tambang Bukit Tambi uses an open pit mining system where one of the factors that can affect mining is water that entering the mining area, so water control must be carried out, one of the ways is by using mine dewatering system. The purpose of this study is 1) To know the debit of water entering the mining area. 2) To design a pumping plan 3) To create an ideal sump design for handling water that entering the mining area. Based on the research, the daily discharge is 32,243.36 m3 / day where the water discharge that can be released by 2 Kenflo XA 125 / 40B pumps is 640 m3 / hour in 50.38 hours and the water control effort is made a sump that must accommodate water amounting to 19,427.26 m3 and after the calculation is obtained a trapezoid-shaped sump design with size length and surface width of 63.7 m, length and width of the base of the sum of 60.9 m and depth of 5 meters.

The increasing demand for a Thermal Hydrolysis Process (THP) to pretreat municipal sludge upstream Anaerobic Digestion (AD) opens the opportunity to further develop and optimise this technology. The optimal THP temperature remains unclear due to the production of refractory compounds at high temperature. A compilation of literature data was conducted to investigate the existence of a temperature sweet spot for the THP applied to municipal sludge. All related reports (n = 43) were included. The THP temperature range impact was assessed in the range of 100 °C–200 °C on four AD and dewatering performance indicators (CH4 production, Volatile Solid Reduction (VSR), Dewaterability (DW) and filtrate quality). Other parameters potentially affecting the performance indicators were also considered. These parameters include the type of sewage sludge and operational conditions related to THP and AD. The impact of all parameters on performance indicators was evaluated with a Kruskal–Wallis statistical test. For THP temperature optimisation, a pairwise comparison, using a Wilcoxon test, was made. A temperature optimum in the [140–160] °C range was proposed. It seemed to minimize the production of refractory compounds, while maximising AD and dewatering performances. It is noteworthy that above 160 °C, the concentration in refractory compounds and soluble COD increases sharply, thus leading to a potential deterioration of WWTP effluent quality. Optimal THP temperature range for an optimal outcome on both sludge and wastewater treatment lines.

Partial nitritation and anaerobic ammonium oxidation (PNA) is a useful process for the treatment of nitrogen-rich centrate from the dewatering of anaerobically digested sludge. A one-stage PNA moving bed biofilm reactor (MBBR) was started up without inoculum at Klagshamn wastewater treatment plant, southern Sweden. The reactor was designed to treat up to 200 kgN d−1, and heated dilution water was used during start-up. The nitrogen removal was >80% after 111 days of operation, and the nitrogen removal rate reached 1.8 gN m−2 d1 at 35 °C. The start-up period of the reactor was comparable to that of inoculated full-scale systems. The operating conditions of the system were found to be important, and online control of the free ammonia concentration played a crucial role. Ex situ batch activity tests were performed to evaluate process performance.

Low geographical conditions and flowed by many rivers and the reduction of retention ponds in Jakarta, then built a reservoir. However, during the implementation period, it was delayed by 9.74%. One of the things that can be done to overcome delays is to choose a method of implementation. The method is diversion and dewatering. The results of the analysis are expected to produce a large comparison of the costs and time of each method. From the analysis results, the cost of implementing the method of soil and rock diversion in the box culvert work is Rp. 363,935,953, while the sandbag diversion method is Rp. 332,805,831. For box culvert work using open pumping dewatering method, the required cost is Rp. 394,637,510. From these data, it was concluded that the difference in the cost of diversion sandbag and rock soil was Rp. 31,130,122. While rock soil and dewatering diversion are Rp. 30,701,557. As well as sandbag diversions with dewatering of Rp. 61,831,679. The results of observations of the implementation time obtained the conclusion that the work of box culvert with sandbag diversion method takes 35 days, and rock soil diversion 49 days while dewatering 63 days. By time comparison the sandbag diversion method is 14 days faster than rock soil diversion, and 28 days compared to the dewatering method. From these data, it can be concluded that in terms of cost and time, the sandbag diversion method is more economical and efficient than the other two methods.

Microalgae harvesting is a major hurdle for the production of high-value microalgal bioproducts on a large scale. Among harvesting techniques, pH-induced sedimentation stands out as an inexpensive and technically viable method. Nevertheless, there is little information available on the application of this method for microalgae cultivated in wastewater. In this context, the present study investigated the optimization of sedimentation parameters for Chlorella sorokiniana harvesting from wastewater. Parameter optimization was statistically determined by the response surface methodology. The optimal values included a velocity gradient of 250 s−1, mixing time of 10 seconds, and pH of 12, which enabled microalgae harvesting efficiencies of more than 97.8%. These optimal parameters also showed resilience through the physico-chemical variation of the photobioreactor effluent. Furthermore, wastewater quality improved significantly after microalgae harvesting. High removal was found for turbidity (97.9–98.3%), apparent color (92.2–97.2%), total Kjeldhal nitrogen (91.0–94.4%), and total phosphorus (92.8–98.6%). Centrifugation, as the dewatering method, and its operational parameters were also evaluated. Sedimentation followed by centrifugation increased the initial microalgae concentration by about 123 times. This study shows the importance of operational optimization and the results can be used as practical guidelines for microalgae harvesting on a large scale.

The presence of clays can make dewatering of tailings from mineral processing challenging. This review focuses on the interaction of clays in tailings under different conditions, including the impact of high salinity. The surface chemistry and aggregation behaviour of clays in suspension are first discussed, and this is then extended to clay aggregation responses during polymer-induced flocculation, with a view to developing an understanding of how flocculant properties and applied shear can be optimised to enhance dewatering processes. There is increasing interest in polymer dosing to high solids tailings streams to enhance dewatering on deposition, and the demands for this process are contrasted against those for conventional flocculation at lower feed solid concentrations. The review concludes by highlighting a number of research challenges, which include that: (i) aggregate structures from polymer-assisted flocculation that are optimal for settling cannot also be assumed to be so for sediment consolidation; (ii) there is scope for reducing longer-term tailings impacts by choosing novel processing routes in the flowsheet design phase, but this requires insights on how tailings may behave after such processing at a much earlier stage; and (iii) most flocculation studies suffer from inconsistent, ill-defined or inappropriate conditions during the preparative stages, which prevent definitive conclusions being drawn on how high salinity impacts upon tailings flocculation, despite evidence that it can change aggregate density.

In this study, wild-type microalgae species isolated from Porsuk river (Central Anatolia, Turkey) investigated as energy production feedstock and carbon dioxide sink. The obtained experimental data have been used for energy evaluation of the whole process and size estimation of large scale microalgae plant. Growth rate, CO2 mitigation rate, lipid, carbohydrate and protein content and natural settling behavior of the isolated species were investigated. The microalgae Gleocystis ampula had the highest growth rate equal to 0.138 +/- 0.008 g l(-1) d(-1) which also was observed to fix carbon dioxide with the highest rate of 0.281 +/- 0.025 g l(-1) d(-1). The highest measured lipid content of 47.32 +/- 0.40 wt% belonged to Scenedesmus quadricauda (I) with an estimated lipid production rate of 51.9 +/- 0.4 mg l(-1) d(-1). The species Kirchneriella lunaris showed the highest carbohydrate proportion being 72.43 +/- 6.40 and Micrococcus sp. had the highest protein content of 58.11 +/- 8.5 wt%. Promising large scale application of microalgae was concluded for biodiesel production and carbon dioxide mitigation just when efficiency of processes improved substantially. An Energy Efficiency of 1.62 was estimated following an ideally designed cultivation and dewatering approach.

Vertical wells are conventionally used to lower leachate levels or pressures in municipal solid waste (MSW) landfills. However, they are not always efficient or even effective, and in some circumstances retro-fitted horizontal wells represent a potential alternative. However, horizontal wells can be difficult to install and there is a lack of data on their performance. This paper describes the trial construction and operation of three horizontal wells in a landfill at Tianziling, China. The trial was used to develop an improved well installation technique, and to demonstrate the viability of the approach in a typical Chinese landfill. Three wells, between 50 m and 56 m in length, were successfully installed using an improved casing-protected directional drilling method. Average leachate flow rates of two wells were 10.66 m3/day and 3.93 m3/day, respectively. After 74 days of drainage, the maximum leachate level drawdown around the highest flow well was 2.7 m and its distance of influence was up to 50 m. Building on the experience gained at Tianziling, a wellfield comprising twelve horizontal wells having a total length of 1000 m was installed at Xingfeng landfill. After 157 days of drainage, a total volume of ~24,000 m3 leachate had been discharged and the leachate level had been lowered to near the elevation of the horizontal wells. This paper indicates the effectiveness of horizontal wells in reducing leachate level in landfills containing MSW typical of that generated in China, and gives data on installation and performance that may be useful for the design and operation of such an approach.

Odor emitted during biosolids handling is a major issue for utilities and may pose a serious nuisance to surrounding communities. The purpose of this study is to assess the effects of solids retention times (SRTs) of mesophilic anaerobic digesters on the odor emission from biosolids dewatered under various shear intensities and polymer doses. It was found that the digester SRT varying from 15 to 50 days had a very limited effect on the odor precursor reduction in biosolids. Hence, no significant variance in odor emission was observed when SRT was evaluated alone. In contrast, the polymer dose and shear intensity used for dewatering showed more effects than SRT on odor emission and biosolids dewaterability. In general, biosolids dewatered at higher shear intensity tended to consume more polymers to achieve the desired cake dryness, and the peak odor emission was found to increase with both the shear intensity and the polymer dose likely due to the increased protein capture and exposure by the polymer and shear used for dewatering.

Globally, innovative treatment systems are needed to incentivise safe faecal sludge management practices and resource recovery. In rural Tanzania 83% of the population do not have access to basic sanitation. Communities rely on on-site sanitation (pit latrines) that are not safely managed and allow for faecal sludge to contaminate groundwater used for drinking. This study reports on the design and evaluation of a novel treatment system; dewatering of faecal sludge in solar drying beds, followed by capturing of faecal sludge leachate and leachate heat sterilisation using a rocket stove fired with agricultural waste. Faecal sludge was manually extracted from 25 pit-latrines in rural Tanzania and analyzed at 0.5 m depth profiles. For aged latrine sludge (1.5 m deep) the ratio of total volatile solids to total solids halved, indicating stabilization. However, densities of Escherichia coli remained elevated (5.6 × 104 cfu g−1). Extracted sludge was loaded (∼0.9–1.35 m3) into drying beds for 21 days and final E. coli densities were highly variable. The leachate was captured from drying beds in 150 L batches and took 40 min to heat to 98 °C in the rocket-stove with a rice husk fuel feeding rate of 48 kg h−1. Heat treatment of leachate completely inactivated 3.1 × 105 cfu/100 ml of E. coli (5.5 log10 reduction) and reduced total coliforms by 99.9% (3.1 log10); reaching safe guideline values for unrestricted agricultural reuse. Thus, the stove is an innovative low-cost technology for treatment of faecal sludge for rural communities in developing countries that produces faecal products that can be safely used in agriculture.

The present study provides an overall view of the effect of the ultrasound treatment on waste activated sludge (WAS) rheological and dewatering properties as well as its impact on the economic balance of a theoretical wastewater treatment plant. The results showed that ultrasonication at 27,000 kJ/kg TS increased the soluble protein concentration (>100%), bound water content (∼25%), and capillary suction time (>100%) of WAS. The molecular weight distribution of the extracellular polymeric substances (EPS) revealed that the ultrasound treatment solubilised a portion of the peptides and low-molecular-weight proteins. The thixotropic behaviour of the WAS was analysed by means of a rheological structural model that defines the time evolution of a structural parameter as a function of kinetic coefficients for the breakdown and build-up processes. The ultrasound treatment reduced the kinetic coefficients for the breakdown process and changed the fast speed of alignment of flocs because of the reduction of WAS structures. Similarly, the creep tests revealed that the ultrasound treatment at 27,000 kJ/kg TS reduced the initial elasticity (∼80%) and the zero-shear rate viscosity (∼60%), which means that the internal structure of the WAS loosened and disrupted. Finally, a techno-economic analysis showed that ultrasonication was not yet economically favourable since its implementation increased 14% the net cost for WAS treatment and disposal. However, a sensitivity analysis illustrated that increasing electricity revenue and reducing biosolids disposal costs through improvement in WAS biodegradability is important to make ultrasound implementation economically attractive.

Excessive coal moisture leads to a lower heating value and power plant efficiency, and increased transportation costs. Therefore, coal stockpile management and moisture control are particularly important in regions with heavy precipitation. This paper and Part 2 address factors influencing moisture retention and migration in coal stockpiles. Part 1 of this paper series simulates phenomena of runoff, infiltration, and drainage in a stockpile after a rainfall event. Part 2 reports the effect of coal particle size and climate conditions on the rate and depth of moisture evaporation process within a coal stockpile. To perform this study, two coal samples were collected from the Witbank mine in South Africa. The results of the present study showed that smaller interparticulate void spaces because of the compaction or fines particles (−0.5 mm fraction) inhibited infiltration, leading to increased runoff volume. An increase stockpile slope increased the amount of runoff due to coal–water contact time reduction. The ability of heavy rainfall to destroy near-surface structures (erosion) happened more readily at stockpiles with high slopes and high fine content. The fine content significantly influenced the dewatering efficiency of drainage. Coals with higher ash contents had stronger moisture retention ability than that of other coals even though coals with low ash contents had a high fine content. This was ascribed to the contribution of the clay minerals, such as kaolinite, in the high ash coal. The results of this paper can be used for the effective management of coal stockpiles to prevent excessive moisture in stockpiles for the best possible utilisation of coal in power plants.

The oil sands industry employs different technologies at pilot and commercial demonstration scales in order to improve the dewatering rate of fluid fine tailings. Of these technologies, centrifugation has advanced to the commercial scale and is playing a major role in the fluid fine tailings management strategy. However, centrifuge technology on its own may not develop the required strength to ensure fine tailings can be incorporated into dry landform reclamation, which requires water contents close to their plastic limit. Hence, it is paramount to combine more than one technology to maximize post-depositional dewatering. Management of the tailings deposit to promote seasonal weathering (freeze–thaw, evaporation and self-weight consolidation) can promote further dewatering. Properly assessing the contributions of the seasonal weathering components is vital to optimizing this strategy. Using the geotechnical properties of centrifuged tailings, the effects of seasonal weathering on tailings were modeled under two different freezing temperature gradients. A coupled analysis combining FSConsol and Unsatcon was used to simulate the deposition scenario similar to the laboratory. The modeling results were found to match the laboratory response reasonably well, indicating the coupled approach proposed in this manuscript is valid and helps to predict the seasonal weathering effects on dewatering.

Sludge rheology is an important parameter for pumping, pipeline transportation, and dewatering. This study was designed to investigate the effect of adding iron powder (IP) to thermal hydro...

Pressurized vertical electro-osmotic dewatering (PVEOD) has been regarded as a feasible method to achieve sludge deep-dewatering, but the dewatering efficiency is still challenged by high electric resistance. This study employed cationic polyacrylamide (CPAM) as a skeleton builder to enhance electro-osmotic flow in PVEOD. The sludge dewatering efficiency and synergistic effect of CPAM and PVEOD were elucidated. The sludge morphology, surface property, extracellular polymeric substances (EPS) destruction and migration, spatial distributions of proteins and polysaccharides, and current changes were investigated. After the addition of optimal CPAM dose, the sludge formed a uniform and porous structure that provided water channels and enhanced electric transport, thus promoting EPS destruction. The sludge moisture content (MC) analysis indicated the more liberation of bound water due to EPS destruction. Besides, the re-flocculation of disintegrated sludge flocs improved the sludge filtration and thus dewaterability. Instantaneous energy consumption (Et,0.5) was optimized and two-step synergistic mechanism was thus proposed. These findings indicated that the combination of CPAM and PVEOD is a promising strategy to broaden the scope of industrial application of sludge deep-dewatering.

Wastewater treatment plants (WWTPs) are important routes for releasing microplastics into the environment, with the produced sludge acting as a recipient of microplastics from wastewater. There is little information on the impact of sludge processes on the number of microplastics in sludge. In this study, the presence of microplastics in sludge produced by the Sari WWTP in northern Iran was investigated. Samples were taken in 3 replications and microplastics larger than 37 μm were extracted. The sludge from primary settling tank, clarifier, after sludge thickener and after aerobic digester, and after dewatering contained 214, 206, 200, 238, and 129 microplastics/g dry weight, respectively. According to the amount of sludge produced for each unit, this equals 280, 362, 599, 601, and 276 million microplastics/day, respectively, of which more than 85% were fibers. The numbers of microplastics in the sludge from the output of the sludge thickener and the aerobic digester did not significantly differ. However, their numbers decreased by more than 50% after dewatering, probably due to the destruction of flocs in the digestive process and the release of attached microplastics, which are returned into the wastewater treatment process with the rejected water. Polyester and polyethylene were the predominant types of fibers and particles, respectively. Given the annual amount of sludge produced, more than 100 billion microplastics enter the environment per year. Wastewater sludge, therefore, is an important source for the emission of microplastics, especially fibers, to the environment, warranting further evaluation of the associated environmental hazards.

Microalgal research has made significant progress in terms of the high-value-added industrial application of microalgal biomass and its derivatives. However, cost-effective techniques for producing, harvesting, and processing microalgal biomass on a large scale still need to be fully explored in order to optimize their performance and achieve commercial robustness. In particular, technologies for harvesting microalgae are critical in the practical process as they require excessive energy and equipment costs. This review focuses on microalgal flocculation, dewatering, and drying techniques and specifically covers the traditional approaches and recent technological progress in harvesting microalgal biomass. Several aspects, including the characteristics of the target microalgae and the type of final value-added products, must be considered when selecting the appropriate harvesting technique. Furthermore, considerable aspects and possible future directions in flocculation, dewatering, and drying steps are proposed to develop scalable and low-cost microalgal harvesting systems.

Addition of conductive materials (CMs) has been reported to facilitate direct interspecies electron transfer (DIET) and improved anaerobic digestion (AD) performance. This review summarises the benefits and outlines remaining research challenges of the addition of CMs with a focus on the downstream processing of AD. CM addition may alter biogas quality, digestate dewaterability, biosolids volume, and centrate quality. Better biogas quality has been observed due to the adsorption of H2S to metallic CMs. The addition of CMs results in an increase in solid content of the digestate and thus an additional requirement for sludge dewatering and handling and the final biosolids volume for disposal. This review highlights the need for more research at pilot scale to validate the benefits of CM addition and to evaluate CM selection, doses, material costs, and the impact on downstream processes. The lack of research on the impact of CMs on the downstream process of AD is highlighted.

Piezoelectric effect was firstly employed to improve dewatering efficiency of sludge. It was found that the piezoelectric effect could be driven directly by the pressure of pressure filtration process, without any additional energy. This piezo-dewatering process coupled piezoelectric effect with pressure filtration could efficiently remove moisture of sludge. Under 0.6 MPa for 2 h, moisture content (MC) and weight of sludge could be reduced to 63.9% and 3.2 g from 96.7% and 50 g by the piezo-dewatering process with 0.45 g t-BaTiO3. This piezo-dewatering efficiency was much higher than that of usual conditioning-pressure filtrations using CaO, FeCl3 or polyacrylamide (PAM) as the conditioners. And the piezo-dewatering process assisted by PAM could further decrease MC and weight of the sludge to 54.9% and 2.1 g, correspondingly, which complied to the advanced dewatering requirement (MC

Poor dewaterability is a bottleneck of the disposal of digestate from food waste (DFW). However, the dewatering mechanism remains unclear due to the complex composition of DFW. Understanding the dewatering mechanism, as well as the transformation of organic/inorganic matters is essential for the DFW management and valorization. In this study, the distribution, transformation, and complex interplay of organic and inorganic matters at different Hydrothermal treatment (HTT) temperatures were comprehensively analyzed to explore the hydrothermal dewatering mechanism of DFW. When HTT was conducted in the temperature range of 120–180 °C, the interstitial water was released as surface or free water because of membrane breaking and size reduction of the solid substrate. Releasing divalent cations increased the Zeta potential of the bulk solution. The weaker electrostatic repulsion between suspended particles made them easier to settle as the centrifugation cake. When the temperature of HTT was above 180 °C, polymerization and aromatization reactions took place gradually for organic matters, and the bound water was further removed. The generated humic substances were more hydrophobic than the raw material. In addition, the humic substance could combine with cationic metals, which decreased the zeta potential of the bulk solution but promoted the aggregation of nanoparticles and enhance the dewaterability of DFW.