Membrane Filter Press Research Articles

Large-Scale Conversion of Livestock Blood into Amino Acid Liquid Fertilizer and Dry Protein Feedstuff: A Case Study

Livestock blood, typically considered a waste byproduct of the slaughter industry, has the potential to be a valuable resource in the environmental and agricultural industries owing to its high protein content. This study reports the mechanisms involved in developing a continuous process capable of processing 5 tons/day of livestock blood into high purity amino acid liquid fertilizer and dried protein feedstuff simultaneously. Large-scale processing units were fabricated for the ultrasonic pretreatment and solubilization of proteins, enzymatic degradation of dissolved proteins for amino acid conversion, solid-liquid separation using a membrane filter press to produce high purity amino acid liquid fertilizer, and microwave drying of the solid component to produce dry protein feedstuff. The main processing units were integrated into a continuous, efficient system. The final amino acid liquid fertilizer and dry protein feedstuff contained >20% amino acids and approximately 78% protein, respectively. An economic feasibility analysis of the integrated system based on an annual processing capacity of 3000 tons of livestock blood yielded a total annual profit of 17.4 million euros (5812 euros/ton). This study presents an efficient and profitable approach to repurposing the waste generated by slaughterhouses toward agriculture and feed production.

Zinc recovery from Waste-to-Energy fly ash – A pilot test study

Zinc recovery from MSWI fly ash using acidic leaching and chemical precipitation was studied at pilot scale. The leached fly ash was re-incinerated in order to destroy toxic dioxins. 75–150 kg/h of fly ash from a Swedish Waste-to-Energy plant was mixed with scrubber liquids from the same flue gas treatment system in a continuously stirred vessel. The resulting slurry was dewatered in a vacuum belt filter. Hydroxide precipitation of the produced leachate, at a pH of around 9, followed by filtration of the formed crystals in a membrane filter press produced a filter cake with up to 80 wt% Zn(OH)2 in dry solids, calculated from Zn(tot). Up to 70% of the zinc content in the fly ash could be recovered. Two 4-hour full scale ash re-incineration tests were performed: leached fly ash was mixed with the waste at a ratio corresponding to a situation where all the fly ash was continuously re-incinerated. The tests showed only an 8% mass increase of produced fly ash, which means that most of it ended up in the bottom ash, although some elements could potentially accumulate in the system if all the fly ash was to be continuously re-incinerated. No negative effects were observed on the bottom ash quality, which suggests that a large portion of the toxic fly ash could be transformed into the bottom ash fraction.

Dewatering of brewer’s spent grain using an integrated membrane filter press with vacuum drying capabilities

ABSTRACTBrewer’s spent grain (BSG) is a by-product of the brewing process, rich in fiber, protein and carbohydrates. Its potential application is limited because of high moisture content (80%). This work presents a process for dewatering BSG using two different sets of membrane filter plates in a filter press with vacuum drying: recessive plates with polypropylene membranes and the innovative Rollfit® plates. A final moisture content of 12-15% was obtained in 15 mm-thick filter cakes, using both types of plates. The dewatering cycle included filtration, membrane-squeezing, and vacuum thermal drying using hot water (~90ºC) as heat source.

Enabling safe dry cake disposal of bauxite residue by deliquoring and washing with a membrane filter press.

Dry cake disposal is the preferred technique for the disposal of bauxite residue, when considering environmental issues together with possible future utilisation of the solids. In order to perform dry cake disposal in an economical way, the deliquoring of the residue must be carried out efficiently, and it is also important to wash the obtained solids well to minimise the amount of soluble soda within the solids. The study presented in this article aims at detecting the most important variables influencing the deliquoring and washing of bauxite residue, performed with a horizontal membrane filter press and by determining the optimal washing conditions. The results obtained from pilot-scale experiments are evaluated by considering the properties of the solids, for instance, the residual alkali and aluminium content, as well as the consumption of wash liquid. Two different cake washing techniques, namely classic washing and channel washing, are also used and their performances compared. The results show that cake washing can be performed successfully in a horizontal membrane filter press, and significant improvements in the recovery of alkali and aluminium can be achieved compared with pressure filtration carried out without washing, or especially compared with the more traditionally used vacuum filtration.

Leaching and recovery of zinc from leaching residue of zinc calcine based on membrane filter press

The feasibility of leaching and recovery of zinc from zinc leaching residue (ZLR) based on a membrane filter press (MFP) was investigated. Experimental results show that zinc calcines with particle sizes of less than 106 μm and chambers of widths of 30 mm are appropriate for establishing uniform filter cakes to obtain acceptable leaching and recovery results. The leaching of zinc from ZLR performed via washing at 90 to 96 °C for 90 min with spent electrolyte using a MFP results in a zinc extraction rate of 97%, and almost all of the zinc leached are recovered after water washing with MFP, thereby avoiding any loss in the ZLR. Compared with the traditional hot concentrated acid leaching process, the process based on MFP as a leaching reactor is able not only to ensure a high extraction rate but also to reduce the leaching time. Moreover, the thickening, pulping, second leaching, washing, filtering and pressing could be integrated and realized using a single MFP.

Experimental investigation on shear strength and permeability of a deeply dewatered sewage sludge for use in landfill covers

This paper presents an experimental study on a deeply dewatered sewage sludge produced by using a new technique of membrane filter press. The experiments involve measurements of sludge composition, basic physical properties, shear strength, water permeability, and leaching toxicity. The measurements of shear strength and permeability were also performed on the sludge specimens soaked in a low acid leachate or distilled water for 1 and 2 months. This is to investigate the influence of chemical change in pore fluid as a result of rainfall infiltration or leachate seepage at landfills. Comparison tests were also carried out on silty clay that is commonly used for landfill cover material. The experimental results show that the deeply dewatered sludge contains 66 % organic content and 85 % water content (dry mass basis). The undrained shear strength of the sludge is >25 kPa even after 2-month soaking in the leachate and distilled water, meeting the requirement of the Chinese standard [CJ/T249-2007, Disposal of sludge from municipal wastewater treatment plant: sludge quality for co-landfilling. Ministry of Building and Construction, P.R. China (in Chinese), 2007]. The measured cohesion and friction angle for the sludge are >20 kPa and 22.3°, respectively. The soaking of sludge specimens in either leachate or distilled water resulted in an increase in frictional angle by several degrees. The water permeability for the sludge ranges from 0.68 × 10−8 to 1.3 × 10−8 cm/s, and permeability after 2-month soaking is less than the minimum requirement for the barrier layer of landfill covers (i.e., 1.0 × 10−7 cm/s). The concentrations of heavy metals leaching from the dewatered sludge are lower than the limit values of leaching toxicity for the wastewater discharge standard of China. The experimental results indicate that deeply dewatered sludge can be used as an alternative material for the barrier layer of landfill covers.

An Integrated Process of Olive Mill Wastewater Treatment

Olive mill wastewater (OMWW) is considered as a challenge for environmental scientists. It is characterized by high values of total organics expressed by chemical oxygen demand (COD), biological oxygen demand (BOD5), and phenols. In this paper, an integrated process of OMWW treatment, which includes lime precipitation, filtration using a novel technology of a membrane filter press (a pilot scale) and a post‐treatment using activated carbon adsorption for the filtrate, was studied. Lime precipitation has removed ∼71% of phenols, ∼39% of COD, and ∼88% of BOD5 with a rise in the total suspended solids (TSS) from 31 kg/m3 (before precipitation) to 69 kg/m3 (after precipitation). The filtration and dewatering operation cycle is approximately 125–150 min. Filtration was examined at different feed pressure (3–5 bar), different slurry concentrations (23–69 kg/m3, dry weight), and filter aid pre‐coat with different additions of diatomite body feed. Specific cake resistance, α, was found to increase with the increase in feed pressure and to decrease with diatomite pre‐coating and slurry concentration increase. However, a further decrease in α values was obtained using diatomite body feed. Cake dewatering, via membrane squeezing, was applied using hot water (65°C) and cake moisture was dropped from ∼64% before squeezing to 35% after squeezing. Twenty minutes were found enough for that stage to be accomplished. With vacuum application, for 30 min, over the hot cakes, cake moisture decreased to ∼20% for cakes with an average thickness of 1 cm. The produced cakes lose more moisture by storing in open air (on the shelf), reaching an equilibrium value of 9% in 2–3 days. Calorific value of produced cake is 15.71 MJ/kg, suggesting strongly its use as an energy source. Activated carbon was used as an efficient sorbent for removing the remaining phenols and total organics from the filtrate as a post‐treatment showing promising results. Maximum removal of phenols and total organics, by lime precipitation and filtrate post‐treatment using activated carbon adsorption, reached ∼99.7% and ∼80%, respectively. A process flowsheet and preliminary cost estimates are presented and compared with other processes. The thermal energy produced by the burning of the produced cakes would be enough for the thermal needs of both the olive mill plant and the proposed treatment process.

Tannery Waste Treatment: Leaching, Filtration and Cake Dewatering Using a Membrane Filter Press (a Pilot Plant Study)

In Alcanena (Portugal) the waste water treatment plant (WWTP) receives tannery waste, after a pretreatment for sulphides and the tanning exhaust baths have been sent to a recovery unit and the municipal waste water from Alcanena residential area. Physical, chemical, and biological treatment processes are involved, and the end products are sludge of ∼71% moisture containing mainly organic matter, sulfides, iron, chromium, and other metals. The sludge is dumped, after stabilization, in a specially designed hazardous waste landfill. In this study, tannery mixed sludge (from chemical and biological treatments) was leached and filtered. Leaching was carried out using sulfuric acid (pH 0.5) to release residual sulfides and metals from the slurry. Hydrogen sulfide (H2S) was flushed out into an oxidation trap (hypochlorite/alkaline tank) in which H2S transforms to soluble sulfate. The acidified sludge was fed into a membrane filter press where it was filtered, acid‐washed, water–washed, membrane‐squeezed, and vacuum‐dried reaching lower moisture levels (20–30%). The process cycle is approximately 101–137 min in our experiments; however, from this work, a cycle of 90 min to produce cakes with 0.9 cm thickness in the industrial scale through cutting some operational time, reaching final moisture of ∼20% at the end of the dewatering cycle, can be estimated. Filtration was carried out at different feed pressure (3–5 bar) with and without diatomite precoating. The effect of different amounts of diatomite body‐feed was studied. Specific cake resistance, α, was found to increase with the increase in feed pressure and to decrease with diatomite precoating and the increased amounts of diatomite body feed. Cake washing was accomplished using 0.05 M H2SO4 (acid washing), to remove residual metals, followed by water washing, to remove cake acidity. Cake dewatering via membrane squeezing was applied using hot water (65°C), and cake moisture was dropped from ∼71% before squeezing to 42% after squeezing. With vacuum application over the hot cakes, for 30 min, cake moisture decreased to ∼20% for cakes with an average thickness of 0.9 cm. Cake chemical analysis showed chromium levels lower than 1000 mg/kg (the maximum Cr concentration allowed by the Portuguese legislation in a solid residue for use in agricultural soil). In addition, produced cake (without diatomite body feed) has a calorific value of 11,000 kJ/kg and accordingly it can be used as a source of energy.

Dewatering of Brewer’s Spent Grain Using a Membrane Filter Press: A Pilot Plant Study

ABSTRACTIn Portugal, brewer’s spent grain (BSG) is produced in huge quantities as a by-product with moisture of 70–80%. Under environmental conditions, because of its high moisture and fermentable sugar content, BSG becomes an environmental problem after a short time (7–10 days). Thus, it must be transported to animal farms to be consumed within that period of time. In this paper, the application of a new technology of membrane filter press to achieve higher drying levels of BSG cake was studied. BSG, after being mixed with water, was filtered, water-washed, membrane-squeezed, and vacuum-dried reaching lower moisture levels (20–30%). The process cycle is approximately 115–180 min. Filtration was carried out at different feed pressure (3–5 bar) and different slurry concentrations (10–30 kg/m3, dry weight) with and without diatomite filter aid precoat. Specific cake resistance, α, was found to increase with feed pressure increase and to decrease with slurry concentration increase with average values 1.86 × 1012 and 2.25 × 1013 m/kg for cakes produced with and without filter aid precoat, respectively. Cake dewatering via membrane squeezing was applied using hot water (65°C) and cake moisture was dropped from ∼80% before squeezing to 51% after squeezing. Five minutes were found to be enough for that stage to be accomplished. With vacuum application over the hot cakes for 30 min, cake moisture decreased to ∼20% for cakes with an average thickness, 0.7 cm. The produced cake loses more moisture by storing in open air (on the shelf), reaching an equilibrium value of 10.1% in less than 2 days. No bacterial activities were observed on the cake by storing for a 6-month period on the shelf. The drying levels achieved allow the cake to be stored in open air without bacterial activities facilitating its use as animal feed, at any time, and as a start material for other related BSG uses.

Hafnium hydroxide filtration, expression, and washing

Hafnium hydroxide filter cake and ammonium sulfate are being recovered from slurry using an expression (membrane) filter press. The process cycle time is approximately 6 hours. Each cycle produces 150 kg of cake containing 75 kg of hafnium oxide. The hafnium hydroxide filter cake has a 4 × 10 5 Pa-specific cake resistance of 10 13 m/kg and is highly compressible. Washing the cake requires two cake volumes water displacement. The four-hour wash cycle requires washing with 5.5 × 10 5 Pa pressure water while compressing the cake to 1.5 × 10 6 Pa. The expressed cake contains 55% moisture, has a dry texture, and crumbles to a powder during handling. The expression dewatering rate varies linearly with moisture content. The filter cake is nearly self-releasing from the multi-monofilament filter cloth.

A Comparative Study of Full-Scale Sludge Dewatering Equipment

A comparative study of 4 different types of full-scale sludge dewatering units was performed in 1990 by I. Krüger AS in co-operation with the equipment suppliers. The purpose of the study was to examine the capability of the dewatering equipment on the “new” sludge types from wastewater treatment plants with N and P removal. The achieved results have formed the basis of a financial evaluation comprising construction and operating costs. The objective of the evaluation is to compare the total costs involved in sludge dewatering and disposal. The relatively cheap types of dewatering units (belt filter press, solid bowl centrifuge) produce dewatered sludge with a lower dry solids content than the more expensive equipment (press centrifuge, membrane filter press). The latter types should consequently primarily be applied where the dewatered sludge has to meet special requirements and in situations in which disposal costs are very high.

Lagoons and ponds

Lagoons and ponds

Development of the Membrane Filter Press for the Processing of Sewage Sludge

The dewatering of sewage sludges using filter presses has been in common use for the past 80 years. The technology was mainly used in the UK for large waste water treatment plants especially where woollen grease was extracted from the sludge. It was also associated with the predrying of sludge prior to incineration in Multi Hearth Furnaces. To meet the growing demand for drier cakes and better capital productivity the membrane filter press has been developed. With the introduction of improved polyelectrolytes, polymer dosing systems, insitu cloth washing and computerised control the average pressing cycle has been reduced from 4-6 hours to under two hours. At the same time the dry solids content of the cake has become more consistent and for most waste waters in excess of 30%. The use of on-site pilot plant trails to determine the design criteria is now the accepted approach enabling sensible scale up and the setting of performance guarantees.

Sludge characterization, removal, and dewatering

In April 1988, E.I. du Pont de Nemours and Company retained the services of CH2M HILL to perform a sludge characterization study, treatability study, remedial design, and to provide construction management services during the remedial action for a slip containing wastewater sludge situated on the Baltimore Harbor. The slip contained an estimated 18,500 cubic yards of sludge that averaged 20 percent solids by weight. Organic compounds were the primary constituents in the sludge, with highest concentrations represented by benzene, ethylbenzene, toluene, and xylenes. During 1989 and 1990, the sludge was removed by a floating dredge, crane, and an air conveyance boom pumping system. A steel sheet pile wall was constructed around the slip to prevent the slip banks from collapsing during removal of the sludge. The sludge was treated using a cationic polymer of high molecular weight during flocculation, and a membrane filter press for dewatering. The sludge cake averaged 52 percent solids by weight. All sludgecake was disposed of offsite in a RCRA-permitted landfill.

4709628 Screw press for dewatering sludge and fiber suspensions : Tad Glowacki, 162 24 Vsweded

In April 1988, E.I. du Pont de Nemours and Company retained the services of CH2M HILL to perform a sludge characterization study, treatability study, remedial design, and to provide construction management services during the remedial action for a slip containing wastewater sludge situated on the Baltimore Harbor. The slip contained an estimated 18,500 cubic yards of sludge that averaged 20 percent solids by weight. Organic compounds were the primary constituents in the sludge, with highest concentrations represented by benzene, ethylbenzene, toluene, and xylenes. During 1989 and 1990, the sludge was removed by a floating dredge, crane, and an air conveyance boom pumping system. A steel sheet pile wall was constructed around the slip to prevent the slip banks from collapsing during removal of the sludge. The sludge was treated using a cationic polymer of high molecular weight during flocculation, and a membrane filter press for dewatering. The sludge cake averaged 52 percent solids by weight. All sludgecake was disposed of offsite in a RCRA-permitted landfill.