Belt Filter Press Research Articles

Internal and surface temperature profiles of spherical biosolids particles during convective drying

The convective drying of spherical biosolids particles from two wastewater treatment plants (Type 1: anaerobic/anoxic treatment with belt filter press dewatering; Type 2: aerobic/anoxic treatment with centrifuge dewatering) was studied under 10 conditions across 44 trials. A wide spectrum of conditions including three drying temperatures (88, 109, and 138 ° C ), two gas velocities (1.6 and 2 m s − 1 ), and particle sizes of 2 cm and 4 cm were investigated. Measured variables included particle mass, center/internal temperature, surface temperature, shrinkage, and qualitative observations of morphological changes. Most samples showed two drying periods, a constant rate period followed by a falling rate period. Additionally, it was found that drying rates and morphological changes depended significantly on particle size and drying intensity (i.e., drying gas temperature and gas velocity) with higher intensities resulting in larger, more porous particles. Internal temperature profiles displayed a consistent pattern, an initial heating phase where internal temperatures quickly rose to approximately the wet bulb temperature of the drying gas, a quasi-constant temperature phase at that temperature, and a final sharp increase/spike to reach equilibrium with the drying gas temperature. Moreover, IR images showed that sub-surface temperatures (between the core and surface) were significantly lower than surface temperatures. Surface temperatures showed a more linear increase throughout drying until equilibrium with the drying gas temperature. The consistent temperature difference between the center and surface, as well as the internal temperature profile, suggests the existence of a drying front, moving radially inward as the particle dries. This research contributes to a better understanding of biosolids drying dynamics, offering insights to improve thermal treatment strategies thereby contributing to the broader field of waste management.

Ciprofloxacin- and azithromycin-resistant bacteria in a wastewater treatment plant

The occurrence of antibiotic-resistant bacteria (ARB) in wastewater treatment plants (WWTPs) has become an occupational and environmental concern. WWTPs are engineered systems that treat wastewater to meet public health standards before release into the environment. The residuals, as either effluent or solids, are then discharged or beneficially recycled into the environment. Since these wastes contain a diverse array of microorganisms, some of which are resistant to commonly used antibiotics, there is a potential for these organisms to spread in the environment via residual recycling and effluent discharge. Human infections with ARB are increasing, and it is not well known how the interaction between humans and the environment plays a role in this process. WWTP workers, who are on the front lines, may come into direct contact with materials containing these microbes. This study aimed to determine the number of ARB present in both air and sewage sludges in a WWTP using nonselective media supplemented with two antibiotics (ciprofloxacin and azithromycin). The densities of total heterotrophic bacteria, ciprofloxacin-resistant bacteria, and azithromycin-resistant bacteria were 7.82 × 105 − 4.7 × 109, 7.87 × 103 − 1.05 × 108, and 2.27 × 105 − 1.16 × 109 CFU/g, respectively. The prevalence [(concentration on medium with antibiotics/concentration on medium without antibiotics) × 100] of ciprofloxacin-resistant bacteria in treated sludge was twice as low as in digested sludge and approximately three times lower than in raw sludge. For azithromycin, the prevalence of resistant bacteria in treated sludge was about the same in digested and nearly twice lower than in raw sludge. Despite a marked reduction in the mean prevalence of resistant bacteria in dewatered treated sludge for both antibiotics, these differences were not significant. The highest prevalence of antibiotic resistance was observed for azithromycin. Similarly, the prevalence of airborne azithromycin-resistant bacteria inside the belt filter press room (BFPR) was nearly seven times higher than the prevalence of airborne ciprofloxacin-resistant bacteria. These concentrations of ARB were not negligible and may represent an exposure pathway for some workers in WWTPs.

Recycling waste sand from slurry shield tunneling: A sustainable filter aid for waste slurry dehydration

The slurry shield tunneling construction process produces waste slurry (WSL), which is often dehydrated using lime as a filter aid. However, a high pH limits the reusability of the mud cake produced, leading to environmental problems. Slurry shield tunneling also produces waste sand (WSA), which the present study evaluates as a substitute for lime via belt filter press testing. The ability of WSA to reduce the mud cake water content and porosity is found to be the same as that of lime, although double the amount is required. Specifically, the optimal amounts of lime and WSA addition are 2% and 4%, respectively, which produce similar total drainage rates and mud cake moisture contents and porosities. Both lime and WSA reduce mud cake macropores, increase small pores and improve compactness. The addition of >2% lime increases the bound water and moisture contents of the mud cake, while WSA reduces the bound water without affecting dehydration. Finally, the use of WSA instead of lime as a filter aid reduces the pH of the mud cake from strongly alkaline (about 12) to near-neutral (about 8). The results show that WSL can replace lime as a filter aid, providing a novel approach to WSL dehydration treatment and WSA reuse that has both environmental and economic benefits.

Analysis of Faecal Sludge Treatment Alternatives to Enhance the Treatment Performance of Wastewater Treatment Plant (WWTP) Denpasar Sewerage Development Project (DSDP) Suwung Denpasar City

Most of the wastewater generated from domestic activities in Denpasar city is treated in an off-site treatment plant located in WWTP DSDP Suwung. This includes faecal sludge that originates from on-site treatment plants. The existing treatment facilities can only treat wastewater that has a maximum biochemical oxygen demand (BOD) concentration of around 225 mg/l while the disposed faecal sludge’s BOD concentration reaches 3,394 mg/l. Therefore, an additional faecal sludge treatment plant needs to be established in order to separate the solid phase from the liquid phase. According to the treatment performance calculation, some alternative treatments can achieve BOD5 and TSS removal of up to 97% and 98% respectively. The selection of the alternative treatment was decided from weighting results of several aspects, such as economic, land use, technological and environmental aspects. The weighting method that was used in this research was Simple Additive Weighting (SAW). The advantage of SAW is its ability to do the assessment highly precisely because it is based on predetermined criteria and preference weights. Based on the weighting result, the treatment technology selected was a Solid Separation Chamber as primary treatment, combined with an Anaerobic Baffled Reactor as a secondary treatment. A Belt Filter-Press was applied to reshape the sludge into a recyclable cake. The required cost is approximately 16 billion rupiahs.

The effect of divalent cation complexation on anaerobically digested enhanced biological phosphorus removal sludge dewatering performance.

The effect of mono- and divalent cation concentrations on digested sludge dewatering characteristics was investigated in a full-scale study at the Harrisonburg-Rockingham Regional Sewer Authority, VA (HRRSA) and at an additional POTW (POTW B). At HRRSA, anaerobic digesters were fed with primary sludge, enhanced biological phosphorus removal (EBPR) WAS, and trucked-in DAF solids from a poultry processing facility, and digested sludge was dewatered by belt filter press. The POTW B digesters received EBPR WAS and primary sludge, and dewatering was by centrifuge. Visual MINTEQ 3.1 (Gustafsson, 2014, Visual MINTEQ 3.1. User's manual) was used to determine cation speciation and struvite, tricalcium phosphate, vivianite, and ferrous sulfide formation at a range of digestion conditions. Significant Mg and Ca complexation was predicted at all conditions evaluated, and the majority of the complexes were monovalent cations. Complexation reduced the divalent cation concentration on the order of 40%. The HRRSA and POTW B data both showed that dewatered cake total solids (TS) increased linearly with uncomplexed divalent cation concentration and that there was an increase of 1.0%-1.1% TS for every additional 1.0meq/L of uncomplexed divalent cations. Because POTW B used centrifuge dewatering, this relationship could be independent of dewatering technique. Further, the relationship between uncomplexed divalent cation concentration and dewaterability suggests that the selectivity of exocellular polymeric substances cation exchange sites is much greater for divalent cations so that monovalent cations only bind to them when their concentrations are much higher than those of the uncomplexed divalent cations. Thus, monovalent cation concentration may not be important in anaerobic digestion or other high alkalinity environments. PRACTITIONER POINTS: It is important to account for complexation in high alkalinity environments such as anaerobic digesters; The findings of this study suggest that dewatering characteristics of anaerobically digested enhanced biological phosphorus removal (EBPR) waste sludge can be significantly improved by preserving cation-mediated exocellular polymeric substances bonding in the solids stream by reducing struvite formation; Data from two full-scale POTW's indicated that dewatered cake TS was increased by 1.0%-1.1% for every 1.0meq/L of dissolved uncomplexed divalent cations in the anaerobic digestate bulk solution; This relationship existed for dewatering both by a belt filter press and by a centrifuge suggesting that this relationship is independent of dewatering technology; Dissolved monovalent cation concentrations may not be important in anaerobic digestion or other high alkalinity environments unless their concentrations are much greater than those of the dissolved divalent cations.

Commissioning of a novel in-line rheometery system in a wastewater treatment plant for more efficient polymer dosing

Urbanisation is putting enormous pressure on wastewater treatment plant facilities. Optimising the liquid and sludge process streams in existing plants is one way of prolonging the life span of such installations. Many Wastewater treatment plants (WWTP) have sludge dewatering installations where treated wastewater sludge is dewatered using belt filter presses amongst others, before final disposal. One of the most expensive inputs in these plants is the polymers used as flocculants. Controlling the optimum dosing in the dewatering process cannot currently be done in real-time. It has been shown that huge savings can be made by optimising the dosing rates of polymers based on the sludge rheology.An Ultrasound Velocity Profiling (UVP) and pressure drop (PD) measurement system was specially designed and commissioned for a WWTP. The system was installed in a WWTP to measure the rheological properties of sludge in-line and in real-time prior to mechanical dewatering using a belt filter press. This non-invasive in-line system was able to accurately measure the rheological parameters in real-time in a 100 mm stainless pipe. It was shown for the first time what the maximum in-line yield stress is that is required for optimum dewatering based on a relationship determined between the yield stress and the total suspended solids in the filtrate exiting the belt filter press.

Online Moisture Measurement of Bio Fuel at a Paper Mill Employing a Microwave Resonator.

This paper investigates online moisture measurement of biofuel employing a strip line cavity resonator at approximately 366 MHz, attached above and below the conveyor belt. An existing sensor design is modified for the factory assembly, and the correct operation has been tested prior to this paper with a small number of measurement points and collected reference samples (n = 67). The purpose is now to concentrate on the accuracy of the measurement and increase the number of measurement points (n = 367). The measurements were made in 5 different lots, and the thickness and moisture properties of the biomaterial mat were varied between minimum and maximum levels by adjusting the settings of the belt filter press that presses pulp slush into a mat. In order to further reduce inaccuracy, at the maximum one standard deviation was allowed from the average height of the equivalent water layer for each dataset, and consequently the number of samples was reduced to 235. A linear fit and a parabola fit were determined for thickness of the equivalent water layer vs. the relative resonant frequency shift: R2 = 0.82 and R2 = 0.78.

Sludge conditioning prior to dewatering: Introducing drainage index as a new parameter

Abstract The conditioning stage is a key parameter for enhancing the efficiency of sludge dewatering. However, the choice of the conditioning procedure (type of flocculant, dosage, mixing conditions) remains a current difficulty. A new index (called drainage index) was introduced to optimize conditioning parameters specifically for sludge thickening on draining table and by extension for sludge dewatering in belt filter press. This easy and quick to measure index was tested via lab-scale drainage experiments. Drainage performance was measured in terms of particles capture rate, final sludge dryness and drainage kinetics. The drainage index allowed to select optimal flocculation conditions prior to gravity drainage. Its relevance to select flocculation conditions insuring a good sludge compression was also demonstrated (except for the polymer selection) from tests carried out in lab-scale filtration–compression device.

Introducing a new GHG emission calculation approach for alternative methane reduction measures in the wastewater treatment of a palm oil mill

Palm oil mill wastewater treatment is a significant source of greenhouse gas (GHG) emissions. The wastewater, palm oil mill effluent (POME), carries substantial amounts of organic matter: If left in ponds, most of this organic matter would decompose relatively quickly into methane (CH4) and carbon dioxide. A belt filter press has been introduced as a means to separate organic matter from the wastewater. Solidified organic matter, the belt press cake recovered with a belt filter press, can be further used as organic fertilizer in the plantation. The aim of this study was to confirm that there is a reduction of CH4 emissions associated with the belt filter press and to find a simple method for determining the reduction at the palm oil mills. CH4 measurements and total organic carbon (TOC) analysis were conducted in a palm oil mill in Malaysia. The emissions were measured both in ponds with solid separation and in baseline open ponds without any CH4 reduction measures. TOC was measured in POME and in belt press cake. By removing organic matter, the measured palm oil mill CH4 emissions of the POME ponds were reduced by 11%. The reduction was as high as 54% in the single pond where the belt filter press was installed. A calculative 13% reduction in methane formation potential was confirmed with TOC measurement. TOC measurement was found to be a simple method worth considering for determining GHG reduction.

Dissolved organic matter characteristics and bacteriological changes during phosphorus removal using ladle furnace slag

A sidestream contains the filtrate or concentrate from the belt filter press, filter backwash, and supernatant from sludge digesters. The sidestream flow, which heads back into the sewage treatment train, is about 1-3% less than the influent flow. However, the sidestream can increase the nutrient load since it contains high concentrations of phosphorus and nitrogen. In this study, the removal of PO4-P with organic matter characteristics and bacteriological changes during the sidestream treatment via ladle furnace (LF) slag was investigated. The sidestream used in this study consisted of 11-14% PO4-P and 3.2-3.6% soluble chemical oxygen demand in influent loading rates. LF slag, which had a relatively high Ca2+ release compared to other slags, was used to remove PO4-P from the sidestream. The phosphate removal rates increased as the slag particle size decreased 19.1% (2.0-4.0 mm, 25.2% (1.0-2.0 mm), and 79.9% (0.5-1.0 mm). The removal rates of dissolved organic carbon, soluble chemical oxygen demand, color, and aromatic organic matter (UV254) were 17.6, 41.7, 90.2, and 77.3%, respectively. Fluorescence excitation-emission matrices and liquid chromatography-organic carbon detection demonstrated that the sidestream treatment via LF slag was effective in the removal of biopolymers. However, the removal of dissolved organic matter was not significant during the treatment. The intact bacterial biomass decreased from 1.64 x 108 cells/mL to 1.05 x 108 cells/mL. The use of LF slag was effective for the removal of phosphate, and the removal efficiency of phosphate was greater than 80% for up to 100 bed volumes.

Prediction of filtrate suspended solids and solids capture based on operating parameters for belt filter press

The control and optimization of belt filter presses in the wastewater treatment industry is still largely dependent on operator intervention. This is mainly due to the lack of predictive models for belt filter press performance. This paper presents correlations determined via a factorial trial for the determination of filtrate suspended solids and solids capture as a function of individual process parameters as well as their interactions. A Box–Behnken experimental based design methodology was used to examine the relationship between the operating parameters and the response variables. The process parameters investigated were polymer concentration, polymer dosing, sludge flow rate and the belt speed. The measured responses were the filtrate suspended solids and sludge cake solids. The measured responses obeyed a second order polynomial relationship and their respective interaction effects of the operating parameters were illustrated on three-dimensional surface graphs. The sludge cake solids concentration was found to be constant over the wide range of experimental conditions. The interaction between the sludge flow rate and polymer dosing rate was the second most influential operating parameter on the filtrate suspended solids following sludge flow rate. The belt speed had an insignificant influence on the filtrate suspended solids and solids capture. The correlation is useful to determine the optimum amount of polymer required if the sludge flow rate changes due to production requirements for constant feed solids concentrations and can be used to develop automated control systems for a particular WWTP.

Superstructure optimization and energetic feasibility analysis of process of repetitive extraction of hydrocarbons from Botryococcus braunii – a species of microalgae

Microalgae are potential resources for producing renewable fuel; however, the process of fuel production from microalgae is itself highly energy consuming and not commercially feasible, yet. Repetitive non-destructive extraction, also called repetitive milking, is a novel method for production of hydrocarbons from Botryococcus braunii – a species of microalgae. In this study, superstructure optimization technique is used to analyse the energetic feasibility of the repetitive milking process and to find the suitable technology options for each stage involved. The repetitive milking process is found to be energetically positive with an average net energy ratio of two for the optimum route. Open pond, cylindrical sieve rotator filter and nanofiltration were found to be the optimum technologies for growth and hydrocarbon production, dewatering and solvent recovery stages, respectively. Belt filter press and vibratory screen filter for dewatering and distillation for solvent recovery are also found to be energetically feasible technologies.

Replace or Rehabilitate? MMSD’s 24 Belt Filter Press Upgrade Challenge

Replace or Rehabilitate? MMSD’s 24 Belt Filter Press Upgrade Challenge

Optimization of belt filter press dewatering of thermally hydrolyzed biosolids: A Blue Plains case study on balancing desired cake solids with filtrate quality

Optimization of belt filter press dewatering of thermally hydrolyzed biosolids: A Blue Plains case study on balancing desired cake solids with filtrate quality

Evaluation of Bacterial Pathogen and Indicator Densities After Dewatering of Anaerobically Digested Biosolids Phase II and III

The sudden increase in indicator bacteria, including fecal coliforms (FCs) and E. coli , was evaluated at several full-scale facilities, in addition to the increase measured during cake storage. The results showed that the sudden increase was a statistically verifiable occurrence at some facilities, but not all, as was the additional increases measured during cake storage. The sudden increase and growth were much more prevalent in processes that utilized centrifuge dewatering compared to belt filter press dewatering. The sudden increase appears to be a result of the reactivation of indicator bacteria that become reversibly non-culturable (RNC) during digestion. Although other hypotheses, such as contamination and presence of inhibitors, cannot be ruled out in all cases. Only one plant that was sampled with high solids centrifugation did not show reactivation and/or regrowth and this plant was different from others in that it utilized thermophilic reactors in series. The results showed a good correlation between the digestion temperature and the reactivation potential and amount of reactivation measured after dewatering. As temperature of digestion increased, the amount of reactivation increased (for plants with reactivation). Similarly, this was generally true, on average for the extent of regrowth. The digestion SRT and VS reduction did not correlate well with reactivation or regrowth. This title belongs to WERF Research Report Series ISBN: 9781780403731 (eBook) ISBN: 9781843397847 (Print)

Impact of dewatering technologies on specific methanogenic activity

Dewatering methods for recuperative thickening and final dewatering can potentially impact methanogenic activity and microbial community. This influences both the feasibility of recuperative thickening to increase solids residence time within a digester, and the utilisation of dewatered digestate as inoculum for new digesters. Thickening technology can reduce methanogenic activity through either air contact (rotary drum, DAF, or belt filter press), or by lysing cells through shear (centrifuge). To assess this, two plants with recuperative thickening (rotary drum) in their anaerobic digester, and five without recuperative thickening, had specific methanogenic activity tested in all related streams, including dewatering feed, thickened return, final cake, and centrate. All plants had high speed centrifuges for final dewatering. The digester microbial community was also assessed through 16s pyrotag sequencing and subsequent principal component analysis (PCA). The specific methanogenic activity of all samples was in the expected range of 0.2–0.4 gCOD gVS−1d−1. Plants with recuperative thickening did not have lower digester activity. Centrifuge based dewatering had a significant and variable impact on methanogenic activity in all samples, ranging between 20% and 90% decrease but averaging 54%. Rotary drum based recuperative thickening had a far smaller impact on activity, with a 0% per-pass drop in activity in one plant, and a 20% drop in another. However, the presence of recuperative thickening was a major predictor of overall microbial community (PC1, p = 0.0024). Microbial community PC3 (mainly driven by a shift in methanogens) was a strong predictor for sensitivity in activity to shear (p = 0.0005, p = 0.00001 without outlier). The one outlier was related to a plant producing the wettest cake (17% solids). This indicates that high solids is a potential driver of sensitivity to shear, but that a resilient microbial community can also bestow resilience. Sensitivity of methanogens to centrifuging does not rule out centrifuges for recuperative thickening (particularly where hydrolysis is rate-limiting), but may impose a maximum return rate to avoid digester failure.

Detection of Legionella spp. by a nested-PCR assay in air samples of a wastewater treatment plant and downwind distances in Isfahan.

Background:Wastewater contains a variety of pathogens and bio -aerosols generated during the wastewater treatment process, which could be a potential health risk for exposed individuals. This study was carried out to detect Legionella spp. in the bio -aerosols generated from different processes of a wastewater treatment plant (WWTP) in Isfahan, Iran, and the downwind distances.Materials and Methods:A total of 54 air samples were collected and analyzed for the presence of Legionella spp. by a nested- polymerase chain reaction (PCR) assay. A liquid impingement biosampler was used to capture bio -aerosols. The weather conditions were also recorded.Results:Legionella were detected in 6% of the samples, including air samples above the aeration tank (1/9), belt filter press (1/9), and 250 m downwind (1/9).Conclusion:The result of this study revealed the presence of Legionella spp. in air samples of a WWTP and downwind distance, which consequently represent a potential health risk to the exposed individuals.

Detroit Water and Sewerage Department – Belt Filter Press Replacement Project

Detroit Water and Sewerage Department – Belt Filter Press Replacement Project

가축분뇨 관리 및 퇴비·액비 이용에 대한 개선방안 고찰 - 논산지역을 중심으로 -

The Ministry of Environment established a plan for advancement of livestock manure management in July 2011 and finalized the "Comprehensive Measures for Advancement of Livestock Manure Management" in May 2012 complementing and strengthening the plan. In this process, it was necessary to investigate the status of discharge of livestock manure and its environmental impact, for example on rivers, groundwater, arable outflow water and soil. We investigated types of livestock husbandry, discharge of livestock manure, and production and use of organic fertilizers and presented the improvement measures of livestock manure management and organic fertilizer use. First, it is necessary to come up with measures to calculate appropriate density and numbers of livestock animals and prevent overcrowded breeding. Second, as many of the private livestock manure treatment facilities are out-dated and their long-term aerated reaction tanks are not regularly managed, it is necessary to find ways to improve those facilities through inspection and diagnosis. In addition, since existing public treatment facilities are designed to add clean water to belt filter press, additional water is needed. Therefore, it is necessary to improve belt filter press in order to decrease the extra water. Finally, although large-scale organic fertilizer plants and resources recycling centers produce good organic (liquid) fertilizers with proper components, it is necessary to establish standards for maturity of liquid fertilizers in order to facilitate efforts to turn livestock manure into resources.

Dewatering of bio-sludge from industrial wastewater plant using an electrokinetic-assisted process: Effects of electrical gradient

An electrokinetic-assisted sludge dewatering (EASD) process was used to evaluate the dewaterability of the bio-sludge cake with moisture content of 68.9%. The cake sample was collected immediately after a belt filter press of an industrial wastewater treatment plant. Results showed that an average of electro-osmosis permeability of 2.2×10−5cm2/V-s was observed. After treatment, the sludge pH values near the anode and cathode were in the range of 6.5–7.5 and 9.5–10.8, respectively. The effectiveness of the EASD process was directly related to the magnitude of the electric current in the system. Increasing the potential gradient would enhance the extent of dewatering efficiency. As a constant electrical gradient of 1.25V/cm was applied, the moisture content of sludge decreased to 63.6% after 4-h treatment. The moisture content of sludge decreased further to 48.8% as the process operated at an applied potential gradient of 5.0V/cm. Energy requirement per unit ton of sludge treated was 17.7–86.5kWh/ton (dry weight). Preliminary cost analysis of the EASD dewatering process showed that approximately a saving of 23% sludge disposal cost could be realized. Results indicated that the EASD process is an economic, viable and effective technology in assisting sludge dewatering.