Skim Latex Serum Research Articles

Pyrolysis of Latex Sediment from Concentrated Latex Industry and Properties of Pyrolytic Products

Concentrated latex is an intermediate rubber product in Thailand. It is an important industry that generates income for the country and Its southern region. The main products of the latex factory were concentrated latex and skim blocks. The industrial waste from the concentrated latex factory is called latex sediment. It appears to be a white mixed light-yellow sludge or a dark brown color, contains magnesium compounds, and phosphorus is an important element. Therefore, finding appropriate measures for rubber production and environmentally friendly industrial waste management is important. Therefore, this study investigates the pyrolysis of latex sediment as an alternative to industrial waste management. Pyrolysis of 100 g of latex sediment was performed at 300 °C, 500 °C, and 700 °C. From the experiment, it was found that the properties of the liquid product from the pyrolysis process at 500 °C were alkaline, with a pH of 9.45. However, acetic acid was the highest amount of organic substance in the liquid product. Substances in the amine and amide groups were also observed, a base result for the liquid product exhibiting an alkaline value. The pH is an important factor in the decomposition of organic substances under anaerobic conditions. Therefore, a 1 wt% liquid product was used in a volume of 13.5 mL, which is the most appropriate amount because it uses the least amount of liquid product to adjust the alkalinity of the skim latex serum before entering the anaerobic fermentation system. Pyrolysis is an environmentally friendly option for managing factory latex sediments for sustainable production and creating a good image for the organization.

Effect of organic loading rate and effluent recirculation on biogas production of desulfated skim latex serum using up-flow anaerobic sludge blanket reactor

High sulfate contents in skim latex serum (SLS) can be reduced by rubber wood ash (RWA). Subsequently, the desulfated skim latex serum (DSLS) can be further anaerobically treated more effectively with the accompanying generated biomethane. In this study, DSLS was treated using an up-flow anaerobic sludge blanket (UASB) reactor operated at 10-day HRT and under mesophilic (37 °C) conditions. The effect of organic loading rates (OLR) at 0.89, 1.79 and 3.57 g-COD/L-reactor∙d on DSLS biodegradability was investigated in Phase I-IV using NaHCO3 as an external buffering agent. Maximum methane production yield of 226.35 mL-CH4/g-CODadded corresponding to 403.25 mL-CH4/L reactor·d was achieved at the suitable OLR of 1.79 g-COD/L-reactor∙d. UASB effluent recirculation which was then applied to replace the NaHCO3. It was found that with 53% effluent recirculation similar to an OLR of 2.01 g-COD/L-reactor∙d, an average of 185.70 mL-CH4/g-CODadded corresponding to 371.40 mL/L reactor·d of methane production was reached. The dominant bacteria in UASB reactor were members of Proteobacteria, Bacteroidota, Firmicutes, and Desulfobacterota phyla. Meanwhile, the archaeal community was majorly dominated by the genera Methanosaeta sp. and Methanomethylovorans sp. The study clearly indicates the capabilities of UASB reactor with effluent recirculation to treat DSLS anaerobically.

Alkaline protease production by thermotolerant Bacillus sp. KU-K2, from non-rubber skim latex through the non-sterile system and its enzymatic characterization

The non-rubber skim latex was used as a substrate for alkaline protease production under a non-sterile system. Among 108 isolates of aerobic spore-forming bacteria, the isolate of KU-K2 was selected as a potent bacterial strain for alkaline protease production. The 16s rRNA gene sequence analysis showed that the KU-K2 strain was closely related to the B. licheniformis with 99.39% similarity. The alkaline protease production from non-rubber skim latex serum was optimized using the Plackett-Burman design (PB) and response surface methodology based on central composite design (CCD). The results showed that the optimized medium consisted of 9.82 g/L skim milk, 0.97 g/L glucose, 0.82 g/L K2HPO4, and 0.02 g/L CoCl2·6H2O gave the highest enzyme production at 6.14 ± 0.13 U/mL. The upscale production in the 5.0 L stirrer fermenter was achieved at 6.78 ± 0.32 U/mL when incubated at 37 °C, 250 rpm with 2.0 vvm of aeration rate for 48 h, which increased by 2.90 folds compared to the un-optimized medium. The optimal pH and temperature for alkaline protease activity were 10.0 and 60 °C, respectively. Zn2+, Fe3+, and Hg2+ metal ions strongly inhibited the crude alkaline protease. This study showed the potential of thermotolerant Bacillus sp. For alkaline protease production using non-rubber skim latex as a substrate which could be applied to reduce the industrial waste from latex industries.

Biodegradation efficiencies and economic feasibility of single-stage and two-stage anaerobic digestion of desulfated Skim Latex Serum (SLS) by using rubber wood ash

The efficiencies of single-stage anaerobic digestion (SSAD) and two-stage anaerobic digestion (TSAD) of desulfated skim latex serum (DSLS) using various rubber wood ash (RWA) loadings were investigated in this study. The experiments on batch processes showed that DSLS gave a higher yield (6–21%) than raw SLS in both SSAD and TSAD. The highest H2 and CH4 yields of 90.64 and 294.53 mL/g-CODadded were achieved with DSLS using RWA loading of 5 g/L (DSLS5) and 10 g/L (DSLS10), respectively in TSAD (thermophilic and mesophilic conditions, respectively). The maximum 305.09 mL/g-CODadded CH4 yield in SSAD was observed for DSLS10. Total energy recovery in TSAD was 5% higher than that in SSAD. However, the cost assessment on continuous AD using kinetics and yield from the batch experiments suggests longer payback time for TSAD (4.36 years) than for SSAD (2.52 years). TSAD is not economically attractive with DSLS10 due to the large total volume of digesters required. This study revealed that RWA can remove sulfate from SLS to enhance biogas production and reduces H2S in the biogas, while TSAD of DSLS was not attractive compared to the conventional SSAD like for some other substrates reported in the literature.

Sulfate removal using rubber wood ash to enhance biogas production from sulfate-rich wastewater generated from a concentrated latex factory

Skim latex serum (SLS) is high-strength wastewater generated from latex processing. Anaerobic treatment of SLS can be enhanced by reducing the sulfate content, which is an inhibitor in the biogas production system. This study investigates the effect of mixing time and rubber wood ash (RWA) loading on sulfate removal from SLS. The optimum sulfate removal efficiency of 42 % was achieved when 10 g/L of RWA was loaded for 10 min. The biogas production efficiency from both desulfated and raw SLS was investigated. The highest 306.36 m L-CH4/g-COD of methane production yield was achieved from desulfated SLS using RWA loading of 10 g/L (DSLS10), which is 16 % higher than the yield generated using raw SLS as a substrate. Moreover, hydrogen sulfide content in the biogas produced by desulfated SLS was two times lower than raw SLS. The results indicate removing sulfate from SLS using RWA before feeding to the anaerobic digestion enhanced biogas production yield and quality.

Involvements of food grade dialdehydic pectin as cross-linker and soy protein as additive in the production of MNP-CLEA-lipase from Hevea brasiliensis

Skim latex from Hevea brasiliensis (rubber tree) contains many useful enzymes that can be utilized to produce value-added products. Lipase recovered from skim latex serum was immobilized via cross-linked enzyme aggregates (CLEA) technology, while supported by magnetic nanoparticles termed ‘MNP-CLEA-lipase’. One of the main advantages of this method is, the biocatalyst can be easily recovered by a magnetic field for recycling. In this research, dialdehydic pectin was used as the cross-linking agent, replacing glutaraldehyde, and soy protein was used as an additive, replacing bovine serum albumin (BSA). The operating conditions for the preparation of the most active MNP-CLEA-lipase were optimized statistically. Dialdehydic pectin and soy protein showed optimum operating conditions at 180 mg/mL and 0.6% (w/v) respectively and with (NH4)2SO4 at 80% saturation, giving a Residual Activity (RA) of 154%. The optimum temperature for MNP-CLEA-lipase was at 40°C (127% RA) while the optimum pH was at 8 (127% RA). It retained 20% RA after 100 days of storage. The reusability test showed that it maintained 7% RA after the 10th cycle. This research showed two advantages; first, that value-added products can be recovered from agricultural waste, and second, by alternating to low-cost food-grade cross-linkers and additives, enhanced biocatalyst can be produced which can be safely used in the beverage and food industries

Screening of macromolecular cross-linkers and food-grade additives for enhancement of catalytic performance of MNP-CLEA-lipase of hevea brasiliensis

Skim latex from Hevea brasiliensis (rubber tree) consist of many useful proteins and enzymes that can be utilized to produce value added products for industrial purposes. Lipase recovered from skim latex serum was immobilized via cross-linked enzyme aggregates (CLEA) technology, while supported by magnetic nanoparticles for properties enhancement, termed ‘Magnetic Nanoparticles CLEA-lipase’ (MNP-CLEA-lipase). MNP-CLEA-lipase was prepared by chemical cross-linking of enzyme aggregates with amino functionalized magnetic nanoparticles. Instead of using glutaraldehyde as cross-linking agent, green, non-toxic and renewable macromolecular cross-linkers (dextran, chitosan, gum Arabic and pectin) were screened and the best alternative based on highest residual activity was chosen for further analysis. Same goes for additives; the traditional use of expensive BSA was replaced with low cost, food grade additives (egg protein, soy protein and milk protein). The optimum condition parameters such as concentration of cross-linker, concentration of additive and concentration of precipitant were determined using one factor at a time (OFAT) method and structural analysis was done by FTIR. The screening results showed that pectin was the best cross-linker (118 % residual activity) and soy protein was the best additive (129 % residual activity) for MNP-CLEA-lipase with optimum conditions of 180 mg/ml pectin, 0.6 % w/v soy protein and 80 % saturation ammonium sulphate. FTIR of MNP-CLEA-lipase showed an Amide I and Amide V bands which originated from silanized magnetic nanoparticles (MNP) and a new band, Amide II was formed prior to the successful CLEA immobilization of lipase enzyme with MNPs.

IMMOBILIZATION OF CLEA-LIPASE OF Hevea brasiliensis ONTO MAGNETIC NANOPARTICLES FOR ENHANCED BIOCATALYTIC PERFORMANCE

Skim latex from Hevea brasiliensis consists of many useful proteins and enzymes that can be utilized to produce value-added products for industrial purposes. In this project, to enhance the properties of the recovered lipase from skim latex serum, this enzyme was immobilized via cross-linked enzyme aggregates (CLEA) technology, and supported by magnetic nanoparticles (MNP-CLEA-lipase). MNP-CLEA-lipase was prepared by chemical cross-linking of enzyme aggregates with amino functionalized MNP, which can easily be separated from the spent media after use by magnetic field. The performances of the newly produced MNP-CLEA-lipase were compared with its unsupported counterpart, CLEA-lipase. The optimum conditions for the preparation of CLEA-lipase was carried out by using 45% saturated (NH4)2SO4 and 50 mM glutaraldehyde (GA), whereas for MNP-CLEA-lipase, it was carried out by using 70% saturated (NH4)2SO4 and 60 mM GA. The optimum pH changes from 6 to 8 when CLEA-lipase is supported, while achieving a maximum of 69.92% residual activity (RA) compared to 20.66% for the unsupported CLEA-lipase. However, the optimum temperature for both are the same (35°C), with MNP-CLEA-lipase achieving 85.89% RA compared to 31.91% for the unsupported ones. Stability studies carried out on both showed that MNP-CLEA-lipase has higher thermal (25–60°C) and pH (5–10) stabilities compared to its unsupported counterparts. As for the reusability of enzymes, MNP-CLEA-lipase retained 56.46% of residual activity after six cycles of reuse. The FESEM results showed that the MNP-CLEA-lipase is a Type 2, which is less structured, and this has bearings towards its activities. FTIR analysis showed the presence of Amide I and Amide II bands in MNP-CLEA-lipase, originating from the newly formed cross-linked between the silanized MNP and CLEA-lipase. Overall, MNP supported CLEA-lipase showed better performance compared to the unsupported biocatalyst.

Continuous two-stage anaerobic co-digestion of Skim Latex Serum (SLS) and Rhizoclonium sp. macro-algae for bio-hythane production

Continuous two-stage anaerobic co-digestion of Skim Latex Serum (SLS) and Rhizoclonium sp. macro-algae for bio-hythane production

Feasibility of bio-hythane production by co-digesting skim latex serum (SLS) with palm oil mill effluent (POME) through two-phase anaerobic process

Hydrogenogenic batch fermentation without nutrients addition was investigated at different SLS: POME mixing ratios of 100:0, 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45,50:50, and 0:100 (Volatile Solid, VS basis) at initial organic concentrations of 21 and 7 g-VS/L. Satisfactory hydrogen yield of 84.5 ± 0.7 mL H2/g-VSadded was achieved from 7 g-VS/L batch having SLS: POME-VS mixing ratio of 55:45. Adding NaHCO3 3 g/L or 0.43 g-NaHCO3/g-VS) in the two-stage anaerobic system at 7 g-VS/L could provide sufficient buffering capacity. Hydrogenogenic effluent from 7 g-VS/L batch at SLS: POME mixing ratio of 55:45 (VS basis) could further generate rather high methane yield of 311.2 ± 8.0 mL- CH4/g-VSadded in themethanogenic stage.According to the experimental results, bio-hythane approximately 55.5 × 106 m3/year with 21% (V/V) of hydrogen, equivalent to51.0 × 106 l-gasoline could be produced potentially from 3.88 × 106 m3 of mixed SLS and POME through the two-stage anaerobic co-digestion.

Use of Ammonium-enriched Skim Latex Serum to Compost Rubber Biomass Wastes and Its Effect on Planting Brassica alboglabra

Ammonium-enriched skim latex serum - used for absorption of contaminating ammonia gas - when composted with other rubber tree wastes, is promising as a good compost. The objective of this research was to utilize ammonium-enriched skim latex serum (S) as a raw composting ingredient after being combined with para sawdust (W1) and para rubber leaves (W2). Several ratios of S, W1 and W2 were experimented in a 15L composting vessel to determine the most effective compost. The best ratio was found to be 3:1:3 by weight at 12-day retention. The modified 30 L composting reactor employed with the derived optimum mixing conditions yielded N, P and K of 2.40, 1.51 and 14.84 %w/w. The growth of Brassica alboglabra after application of this compost combined with a chemical fertilizer generated the highest fresh weight (4.48 g/plant). Thus, compost from these wastes could be used as a fertilizer and logically should contribute to cost saving of waste disposal.

Treatment of effluent (skim latex serum) from a rubber processing plant with Fenton’s reagent

Treatment of effluent (skim latex serum) from a rubber processing plant with Fenton’s reagent

THE EFFECT OF OPERATING CONDITIONS ON CRITICAL FLUX AND REVERSIBLE FOULING IN MEMBRANE FILTRATION USING GAS SPARGING TECHNIQUE

Gas sparging method utilizing injection of nitrogen gas was employed during the ultrafiltration of the natural rubber effluent (latex serum). The objective of this research was to investigate the effect of gas sparging on the critical flux and the observed reversible cake layer resistance during the ultrafiltration of skim latex serum. Experiments were conducted using a 100 kDa MWCO tubular membrane (PCI Membrane System) mounted vertically. The effect of operating parameters, such as feed flow rate, concentration and transmembrane pressure were investigated. The results showed that when the feed flow rate was increased, the permeate was correspondingly increased and the reversible cake resistance decreased. In this research a feed flow rate of 1400 ml/min and transmembrane pressure of 13.00 psig resulted in the maximum total permeate flux of 70.80 L/m2h. Results from this study obtained so far showed that the use of gas sparging has been able to increase total permeate flux between 8.3% and 145.3% compared to non-gas sparged condition. Critical flux occurrence was increased to 82.63% above the value obtained for non-sparged condition and applied transmembrane pressure can be reduced to 2.4% of the non-gas sparged condition.Keyword: skim latex serum, reversible fouling, gas sparged, critical flux

Bio-hydrogen and bio-methane potentials of skim latex serum in batch thermophilic two-stage anaerobic digestion

Anaerobic digestion by two-stage process, containing hydrogen-producing (acidogenic) first stage and methanogenic second stage, has been proposed to degrade substrates which are difficult to be treated by single stage anaerobic digestion process. This research was aimed to evaluate the bio-hydrogen and the bio-methane potentials (BHP and BMP) of skim latex serum (SLS) by using sequential batch hydrogen and methane cultivations at thermophilic conditions (55°C) and with initial SLS concentrations of 37.5–75.0% (v/v). The maximal 1.57L H2/L SLS for BHP and 12.2L CH4/L SLS for BMP were both achieved with 60% (v/v) SLS. The dominant hydrogen-producing bacteria in the H2 batch reactor were Thermoanaerobacterium sp. and Clostrdium sp. Meanwhile, the CH4 batch reactor was dominated by the methanogens Methanosarcina mazei and Methanothermobacter defluvii. The results demonstrate that SLS can be degraded by conversion to form hydrogen and methane, waste treatment and bioenergy production are thus combined.

Anaerobic digestion of skim latex serum (SLS) for hydrogen and methane production using a two-stage process in a series of up-flow anaerobic sludge blanket (UASB) reactor

A series of up-flow anaerobic sludge blanket (UASB) reactors operated under thermophilic conditions was used to investigate the two-stage anaerobic process for continuous hydrogen and methane production from skim latex serum (SLS). The first reactor for producing hydrogen was operated by feeding 38 g-VS/L-SLS at various hydraulic retention times (HRTs) of 60, 48, 36, and 24 h. The optimum hydrogen production yield of 2.25 ± 0.09 L-H2/L-SLS was achieved at a 36 h HRT. Meanwhile, the effluents containing mainly with acetate was fed to the second UASB reactor for methane production at 9-day HRT and could be converted to methane with the production yield of 6.41 ± 0.52 L-CH4/L-SLS. The efficiency of organic matters removal obtained from this two-stage process was 62%. The present study shows high value fuel gases in a form of hydrogen and methane can be potentially generated by using a continuous two-stage anaerobic process, in which available organic matters is simultaneously degraded.

Utilization of Waste from Para Rubber Industry to Produce Compost

A survey of cooperative concentrated rubber latex industry in southern Thailand showed that most of them do not have adequate treatments for their wastes. Especially, skim latex serum (SS) with high source of ammonia is a main wastewater generated from their industries and concentrated latex sludge (CS) with high source of phosphorus is a main solid waste obtained from their industries. It was noted that both of the wastes cause environment problems. Water pollution and bad smell of NH3from these waste systems have also been generated and affected to human health. One low investment possibility is the elaboration of these wastes by composting because these wastes contain some nutrients (N, P, K) in available forms resulting in high potential to add value for fertilizer production. However, both of the wastes have a small amount of organic matter content that need to be mixed with other materials with high organic matter such as sawdust (SD). Thus, the aim of this research was to investigate the utilization of these wastes to produce compost. In this work, the SS, CS and SD were composted in specially designed composting vessel (6L) with various mixing ratios of the SS, CS and SD in order to examine the optimized mixing condition and physical properties of the compost. Each treatment was composted with 60 days of composting duration. The performance of composting process was analyzed in term of the following: temperature, pH, electric conductivity, total organic carbon, total nitrogen, total phosphorus and C/N ratio. The analysis of temperature, pH, and electric conductivity was measured every day while the analysis of total organic carbon, total nitrogen, total phosphorus and C/N ratio was investigated every 10 days. According to the results, the optimized mixing ratio of SS, CS and SD for composting was 1:1:1. The final resultant compost was feasible for agricultural use. From the view point of compost qualities, it was in the range of the Thai compost standard with 7.91 of pH, 15.06 (%w/w) of total organic carbon, 1.24 (%w/w) of total nitrogen, 0.69 (%w/w) of total phosphorus and 21.6 of C/N ratio.

Treatment of Skim Latex Serum Using Gas Sparged Ultrafiltration

AbstractThe major pollutants from a natural rubber processing factory have high organic content and emit an offensive smell due to the biodegradation of the organic matter. In latex concentrate factories, the main sources of effluent are the skim latex serum and washings from all process equipment. This paper presents an application of membrane technology that involves gas sparging for the treatment of skim latex serum. A semi‐pilot‐scale system using a PVDF vertical tubular membrane (MWCO 100,000) was installed as the experimental setup. Nitrogen gas was bubbled vertically upwards at flowrates ranging from 300 to 500 ml/min. Results obtained thus far show that gas sparging has increased the permeate flux between 1.37% and 146.34% compared to non‐gas sparged conditions. In terms of permeate quality, the reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 83%, 95%, 67%, 77%, 51%, 74%, respectively, for the gas‐sparged condition. Under non gas‐sparging conditions, reductions achieved for suspended solids, total solids, COD, BOD, total nitrogen and ammoniacal nitrogen were 92%, 96%, 67%, 72%, 60%, 75%, respectively.

Laboratory studies on the use of Eichhornia crassipes in treatment systems for skim latex serum

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