Bioaugmentation of latex rubber sheet wastewater treatment with stimulated indigenous purple nonsulfur bacteria by fermented pineapple extract

AbstractBackgroundTreating latex rubber sheet wastewater often leads to the generation of a rotten-egg odor from toxic H2S. To increase the treatment efficiency and eliminate H2S, purple nonsulfur bacteria (PNSB), prepared by supplementing non-sterile rubber sheet wastewater (RAW) with fermented pineapple extract (FPE), were used to treat this wastewater under microaerobic light conditions. The following 3 independent variables: chemical oxygen demand (COD), initial pH and FPE dose were investigated using the Box–Behnken design to find optimal conditions for stimulating the growth of indigenous PNSB (PNSBsi).ResultsThe addition of 2.0% FPE into RAW, which had a COD of 2000mgL-1 and an initial pH of 7.0, significantly decreased oxidation reduction potential (ORP) value and stimulated PNSBsi to reach a maximum of 7.8logcfumL-1 within 2d. Consequently, these PNSBsi, used as inoculants, were investigated for their ability to treat the wastewater under microaerobic light conditions. A central composite design was used to determine the optimal conditions for the wastewater treatment. These proved to be 7% PNSBsi, 0.8% FPE and 4d retention time and this combination resulted in a reduction of 91% for COD, 75% for suspended solids, 61% for total sulfide while H2S was not detected. Results of abiotic control and treatment sets indicated that H2S was produced by heterotrophic bacteria and it was then effectively deactivated by PNSBsi.ConclusionsThe stimulation of PNSB growth by FPE under light condition was to lower ORP, and PNSBsi proved to be effective for treating the wastewater

Effect of Silicon Carbide on the Properties of Natural Rubber Blends with EPDM Rubber

Blends of natural rubber/ ethylene propylene diene monomer were prepared in an internal mixer. The semi-EV of sulphur was used. The effect of the silicon carbide (SiC) level (5, 10, 15, and 20 phr) on the cure characteristic, mechanical, thermal and morphology properties of silicon carbide ï¬lled 30:70 NR/EPDM were studied. The curing properties show that the tc90 and tS2 of NR/EPDM blends increased with the increasing SiC loading. The effect of SiC loading on the tensile strength of NR/EPDM blends showed that tensile of vulcanizates increased with the increasing SiC up until 10 phr, extra addition of SiC would deteriorate the tensile properties. The thermal oxidative property of SiC filled NR/EPDM were satisfactory at all SiC loadings

Use of wood vinegar to enhance 5-aminolevulinic acid production by selected Rhodopseudomonas palustris in rubber sheet wastewater for agricultural use

AbstractThis study aimed to produce inexpensive 5-aminolevulinic acid (ALA) in a non-sterile latex rubber sheet wastewater (RSW) by Rhodopseudomonas palustris TN114 and PP803 for the possibility to use in agricultural purposes by investigating the optimum conditions, and applying of wood vinegar (WV) as an economical source of levulinic acid to enhance ALA content. The Box–Behnken Design experiment was conducted under microaerobic-light conditions for 96h with TN114, PP803 and their mixed culture (1:1) by varying initial pH, inoculum size (% v/v) and initial chemical oxygen demand (COD, mg/L). Results showed that the optimal condition (pH, % inoculum size, COD) of each set to produce extracellular ALA was found at 7.50, 6.00, 2000 for TN114; 7.50, 7.00, 3000 for PP803; and 7.50, 6.00, 4000 for a mixed culture; and each set achieved COD reduction as high as 63%, 71% and 75%, respectively. Addition of the optimal concentration of WV at mid log phase at 0.63% for TN114, and 1.25% for PP803 and the mixed culture significantly increased the ALA content by 3.7–4.2times (128, 90 and 131μM, respectively) compared to their controls. ALA production cost could be reduced approximately 31times with WV on the basis of the amount of levulinic acid used. Effluent containing ALA for using in agriculture could be achieved by treating the RSW with the selected ALA producer R. palustris strains under the optimized condition with a little WV additive

Using machine learning to predict the performance of a cross-flow ultrafiltration membrane in xylose reductase separation

This study provides a new perspective for xylose reductase enzyme separation from the reaction mixtures—obtained in the production of xylitol—by means of machine learning technique for large-scale production. Two types of machine learning models, including an adaptive neuro-fuzzy inference system based on grid partitioning of the input space and a boosted regression tree were developed, validated, and tested. The models’ inputs were cross-flow velocity, transmembrane pressure, and filtration time, whereas the membrane permeability (called membrane flux) and xylitol concentration were considered as the outputs. According to the results, the boosted regression tree model demonstrated the highest predictive performance in forecasting the membrane flux and the amount of xylitol produced with a coefficient of determination of 0.994 and 0.967, respectively, against 0.985 and 0.946 for the grid partitioning-based adaptive neuro-fuzzy inference system, 0.865 and 0.820 for the best nonlinear regression picked from among 143 different equations, and 0.815 and 0.752 for the linear regression. The boosted regression tree modeling approach demonstrated a superior capability of predictive accuracy of the critical separation performances in the enzymatic-based cross-flow ultrafiltration membrane for xylitol synthesis

Recent advances in process improvement of dark fermentative hydrogen production through metabolic engineering strategies

Biological means of hydrogen (H2) production has attracted tremendous research and development attention. Dark fermentation provides a possible way of producing H2 from a range of renewable energy sources, including wastewater. During fermentation, various metabolites are formed to create a complex metabolic flux network. Insufficient focus has been placed on the metabolic engineering that is intrinsic to fermentation. This current review summarizes the biochemical pathways occurring in the metabolic network of dark fermentation and how the key operational factors influence metabolism during dark fermentation. Recent developments and strategies for metabolic engineering that have been described to enhance H2 production are recommended. Finally, the economic analysis related to bio-H2 production and prospects is examined. It is envisaged that this study can give beneficial aspects in terms of fundamental knowledge, understanding, and the latest technology for scientists and research engineers in the field of bio-based H2 generation

Fouling characteristics and cleaning approach of ultrafiltration membrane during xylose reductase separation

Many operating parameters of ultrafiltration (UF) are playing a crucial role when using a polyethersulfone membrane to separate xylose reductase (XR) enzyme from reaction mixtures during xylitol synthesis. The present study focuses on the separation of XR enzyme using a cross-flow ultrafiltration (UF) membrane. The filtration process was analyzed using the three effective variables such as filtration time, cross-flow velocity (CFV), and the transmembrane pressure (TMP), which were ranging from 0 to 100 min, 0.52 to 1.2 cm/s and 1–1.6 bar, respectively. Then, using the resistance in series model, the hydraulic resistance for alkali chemical cleaning during XR separation was estimated. During separation, increased TMP showed a positive-flux effect as a driving force, however, fouling and polarized layer were more prominent under higher TMP. Increased CFV, on the other hand, was found more efficient in fouling control. In terms of the membrane cleaning techniques, an alkaline solution containing 0.1 M sodium hydroxide was shown to be the most effective substance in removing foulants from the membrane surface in this investigation. Cleaning with an alkaline solution resulted in a maximum flux recovery of 93% for xylose reductase separation. This work may serve as a useful guide to better understand the optimization parameters during XR separation and alleviating UF membrane fouling induced during XR separation

รายงานวิจัยฉบับสมบูรณ์โครงการ การเพิ่มประสิทธิภาพการบำบัดน้ำเสียจากอุตสาหกรรมน้ำยางพาราข้นโดยระบบหมักไร้อากาศซัลฟิโดเจนิคอัตราสูงและการผลิตกรดซัลฟูริกจากก๊าซชีวภาพเสีย

สำนักงานกองทุนสนับสนุนงานวิจั

Development of Data-Driven Models to Predict Biogas Production from Spent Mushroom Compost

In this study, two types of data-driven models were proposed to predict biogas production from anaerobic digestion of spent mushroom compost supplemented with wheat straw as a nutrient source. First, a k-nearest neighbours (k-NN) model (k = 1–10) was constructed. The optimal k value was determined using the cross-validation (CV) method. Second, a support vector machine (SVM) model was developed. The linear, quadratic, cubic, and Gaussian models were examined as kernel functions. The kernel scale was set to 6.93, while the box constraint (C) was optimized using the CV method. Results demonstrated that R2 for the k-NN model (k = 2) was 0.9830 at 35 °C and 0.9957 at 55 °C. The Gaussian-based SVM model (C = 1200) provided an R2 of 0.9973 at 35 °C and 0.9989 at 55 °C, which are slightly better than those achieved by k-NN. The Gaussian-based SVM model produced RMSE of 0.598 at 35 °C and 0.4183 at 55 °C, which are 58.4% and 49.5% smaller, respectively, than those produced by the k-NN. These findings imply that SVM modeling can be considered a robust technique in predicting biogas production from AD processes as they can be implemented without requiring prior knowledge of biogas production kinetics

Effect of organic loading rate on methane and volatile fatty acids productions from anaerobic treatment of palm oil mill effluent in UASB and UFAF reactors

Anaerobic treatment of palm oil mill effluent (POME) with the separation of the acidogenic and methanogenic phase was studied in an up-flow anaerobic sludge blanket (UASB) reactor and an up-flowanaerobic filter (UFAF) reactor. Furthermore, the effect of OLR on methane and volatile fatty acid productions in UASB and UFAF reactors was investigated. In this research, UASB as acidogenic reactor wasused for volatile fatty acid production and UFAF as methanogenic reactor was used for methane production. Therefore, POME without pH adjustment was used as influent for the UASB reactor. Moreover, the syntheticwastewater with pH adjustment to 6.00 was fed into the UFAF reactor. The inoculum source for both reactors was the combination of POME sludge collected from the CSTR of a POME treatment plant and granulesludge collected from the UASB reactor of a frozen sea food industry treatment plant. During experimental operation, the organic loading rate (OLR) was gradually increased from 2.50 to 17.5 g COD/l/day in theUASB reactor and 1.10 to 10.0 g COD/l/day in the UFAF reactor. Consequently, hydraulic retention time (HRT) ranged from 20.0 to 2.90 days in the UASB reactor and from 13.5 to 1.50 days in the UFAF reactor.The result showed that the COD removal efficiency from both reactors was greater than 60.0%. In addition, the total volatile fatty acids increased with the increasing OLR. The total volatile fatty acids and acetic acidproduction in the UASB reactor reached 5.50 g/l and 4.90 g/l, respectively at OLR of 17.5 g COD/l/day and HRT of 2.90 days before washout was observed. In the UFAF reactor, the methane and biogas productionincreased with increasing OLR until an OLR of 7.50 g COD/l/day. However, the methane and biogas production significantly decreased when OLR increased up to 10.0 g COD/l/day. Therefore, the optimum OLR inthe laboratory-scale UASB and UFAF reactors were concluded to be 15.5 and 7.50 g COD/l/day, respectively

Integrative Effects of Sonication and Particle Size on Biomethanation of Tropical Grass Pennisetum purpureum Using Superior Diverse Inocula Cultures

Biogas from the fast growing crop, Pennisetum purpureum, has received considerable attention in Southeast Asia since wastewater and bio-waste materials are almost completely utilized. To overcome slow hydrolysis, a rate-limiting step in anaerobic digestion of lignocellulosic biomass, superior microorganism culture, size reduction, and sonication pretreatment were co-applied. In the first experiment, the selection of anaerobic microbial culture to be used in digestion, so-called inoculum, was carried out. Specific anaerobic activities for hydrolysis and methanogenesis of sludge from different sources, a slurry digester of cattle farm (CF) and a wastewater digester of rubber latex factory (RL) were assessed. Results revealed a remarkable synergistic capability in the combined sludge, adding 10% and 49% to the overall biomethanation efficiency over the individual CF and RL sludges. In the second part, interactive effects of size reduction and sonication intensity were studied. Biomethanation efficiency as methane yield increased by 62% by size and 115% by sonication variation, but when optimally combined an additional gain of 40% was recorded. The regression model generated could estimate the energy yield increase as a function of size and sonication intensity with a satisfactory statistical precision R2 of 0.945