Initial pH Adjustment Research Articles

Removal of Reactive Dye from Textile Mill Wastewater by Leading Electro-Coagulation Process Using Aluminum as a Sacrificial Anode

This work presents the highest color removal efficiency for Textile wastewater by Electrocoagulation (EC) process using Aluminum as a sacrificial anode which is presently used for the purification of many types of water and wastewater. The effecting parameters such as applied electrical current, electrolysis time and initial pH were studied to achieve higher removals. In this process, sample was taken from real effluent of reactive dyes fabric. The performance of Electrocoagulation process was carried out in batch reactor at regular interval of 20 minutes. Obtained results indicated the most effective color removal efficiency was achieved at 0.75A of applied electrical Current. They were (97.5% - 98.1%), at electrolysis time of 120 minutes, pH10, pH7 respectively and COD removal efficiency was (54 % - 65%) at 0.75A, 0.9A respectively. In this work, the initial pH did not strongly affect the removal efficiencies significantly over a wide range. Therefore, adjustment of initial pH before treatment was not required in this practical application. The power consumption was found to be 6 kWh/m3. To determine COD removal rate dependency to electrical current, a kinetic study was carried out and data were in good covenant with the first order kinetic model.

Removal of bromophenol blue dye from aqueous solutions through the synthesis and characterization of a polymer-clay composite

ABSTRACTIn this study, the synthesis of a clay-polymer composite was carried out by the in-situ polymerization method of two biopolymers, Alginate-Chitosan (Alg-Chit), with the intercalation of an organo-modified clay, for the removal of bromophenol blue dye (BP-Dye). For this purpose, a natural Montmorillonite clay from Mexico was modified with a cationic surfactant, in order to exchange the cations of the clay galleries with those of the surfactant, and to change its nature from hydrophilic to hydrophobic. Moreover, the synthesis of the copolymer was carried out using different ratios between both biopolymers. Once the copolymer was obtained, it was characterized through FTIR technique. On the other hand, the modified clay was used to obtain the polymer-clay composites using a ratio of 2%-wt of the homopolymer, and the obtained material was characterized with the same technique. Finally, a contact test was carried out by preparing a solution of BP-Dye at a concentration of 5 mg/L, with and without initial pH adjustment, for 1 h, in a bath at controlled room temperature and constant stirring (100 rpm). After this time, phases were separated, and the quantification of the dye was carried out by UV-Vis spectroscopy.

Sulfate radical induced degradation of Methyl Violet azo dye with CuFe layered doubled hydroxide as heterogeneous photoactivator of persulfate

Persulfate (PS)-based advanced oxidation processes have aroused considerable attentions due to their higher efficiency and wider adaptability to the degradation of bio-recalcitrant organic contaminants. In this study, Cu-Fe layered doubled hydroxide (CuFe-LDH) was employed to degrade Methyl Violet (MV) through heterogeneous photo-activation of PS under visible-light irradiation. The reaction kinetics, degradation mechanism, catalyst stability were investigated in detail. Under the conditions of CuFe-LDH (3:1) dosage 0.2 g/L, PS concentration 0.2 g/L and without initial pH adjustment, 20 mg/L MV was almost completely degraded within 18 min. Electron Spin Resonance (ESR) test and radical quenching experiment indicated that sulfate radicals (SO4-) were the dominant reactive oxidants for the MV decolorization, while hydroxyl radicals (OH) were also involved. The CuFe-LDH/PS/Vis system was applicable at wide range of pH level (3–9). However, extreme pH level would lead to the reduction or transformation of SO4-. The catalyst CuFe-LDH exhibited excellent stability and maintained relatively high catalytic activity to PS even after four recycles. Mechanism study revealed that the redox cycle of Fe3+/Fe2+ and Cu2+/Cu3+ assisted by visible-light irradiation accounted for the enhanced generation of radicals in CuFe-LDH/PS/Vis system, resulting in the improved degradation of organic contaminants. Overall, the CuFe-LDH/PS/Vis process could be a promising approach for the removal of refractory organic pollutants in wastewater.

Phagotrophic microalgae production from waste activated sludge under non-sterile conditions

In this study waste activated sludge (WAS) was sonicated to release bacteria-sized volatile solids (VS) from flocs, after initial pH adjustment to 10 for higher energy efficiency. The released VS supported growth of phagotrophic alga Ochromonas danica. Initial-rate growth experiments confirmed the Monod-type kinetics but the specific cell growth rate, μ, correlated with the prey-to-predator ratio, i.e., the ratio of (fed VS concentration)-to-(initial O. danica concentration), significantly better than with the VS alone, as the typical Monod dependency on soluble substrates. The best-fit kinetics had the following parameters: μmax = 0.198 h−1 and KM = 1.056 (g-VS/g-algae). Post-sonication reflocculation could render particles too large to ingest by O. danica; therefore, pH and VS effects on reflocculation were investigated. Batch cultivations were then conducted in fermentors at pH 5, under nonsterile conditions. Algae number reached 8.86 × 1010 L−1 after 20 h, corresponding to ∼2.3 g/L dry-weight and volumetric algae productivity of 2.8 g/L-day. VS reduction was 38%, giving an O. danica VS yield of 44.5%. The ultrasonication-algae process can be used to produce algae while achieving at least partial WAS treatment.

The response of metabolically active Clostridium community to initial pH shift is closely correlated with microbial Fe(III) reduction in flooded paddy soils

Soil pH could be greatly affected by agriculture practices in paddy soils, in which microbial Fe(III) reduction is a prevalent and important biogeochemical process. There is increasing evidence that microbial fermentative processes can play an important role in Fe(III) reduction. In this study, the response of metabolically active Clostridium community to initial pH adjustment was investigated to elucidate the mechanism of the effects of soil pH on microbial Fe(III) reduction through fermentative microbes. Two paddy soils with different original pH were incubated anaerobically for 40 days. The initial pH of alkaline paddy soil (Baodi district; pH 7.89) was adjusted to acidic levels (approximately pH 5.2), and the initial pH of acidic paddy soil (Nanchang county; pH 5.17) was adjusted to alkaline levels (approximately pH 7.9). The abundance and the structure of metabolically active Clostridium community were measured on days 0, 1, 5, 10, 20, and 40 during anaerobic incubation. Decreasing the initial pH of alkaline paddy soil decreased the Clostridium abundance by 3.77 × 104 to 1.30 × 107 copies g−1 soil, while increasing the initial pH of acidic paddy soil decreased the Clostridium abundance by 1.25 × 108 to 1.80 × 1010 copies g−1 soil within the first 20 days. Decreased initial pH stimulated the growth of H2-producing Clostridium species, while increased initial pH was conducive to the growth of Fe(III)-reducing Clostridium species. The dynamics of the abundance and structure of Clostridium community were closely correlated with processes of hydrogen production and Fe(III) reduction. Decreased pH could inhibit Fe(III) reduction by reducing the abundance and changing the structure of Clostridium community. However, the effects of increased pH on Fe(III) reduction were not obvious as a result of stimulation of the growth of Fe(III)-reducing Clostridium species and H2 utilization ability. Decreasing the initial pH of alkaline paddy soil and increasing the initial pH of acidic paddy soil led to significant decreases in the abundances and great differences in the structures of metabolically active Clostridium community. This study further demonstrated that fermentative microbes could play an important role in Fe(III) reduction via direct and indirect effects, and their optimum pH for growth was closely related to the inherent soil pH.

Photochemical Degradation of Organic Pollutants in Wastewaters

In the present work, the photochemical treatment of a synthetic wastewater in a batch recycle photochemical reactor using ultraviolet irradiation (254 nm, 6 W), hydrogen peroxide and ferric ions was studied. Reactor volume was 250 mL with 55.8 mL of irradiated volume in the annular photoreactor. The synthetic wastewater was composed mainly of organic carbon. The effect of initial total carbon (136-1080 mg L-1), initial H2O2 amount (1332-5328 mg L-1), pH, and Fe(III) presence (2-40 ppm), on total carbon (TC) removal was studied. Each experiment lasted 120 min, and the process was attended via pH and TC concentration. Direct photolysis in the absence of any oxidant had practically no effect on TC removal. Regarding the effect of initial TC concentration in the wastewater keeping the same initial hydrogen peroxide concentration (2664 mg L-1), it was observed that for 136-271 mg L-1 TC, around 60% TC removal was achieved, while when initial TC was increased at 528 mg L-1, the TC removal observed decreased to 50%. For a further increase in TC at 1080 mg L-1, TC removal dropped to 14%. Initial pH adjustment of the wastewater resulted in slight variations of the TC removals achieved. Finally, adding Fe(III) in the process was beneficial in terms of TC removal obtained. Particularly, the addition of 40 ppm Fe(III) in the presence of 2664 mg L-1 H2O2 and initial TC equal to 528 mg L-1 increased the TC removal from 50% to 72%.

Enhanced bioelectricity generation of air-cathode buffer-free microbial fuel cells through short-term anolyte pH adjustment

Short-term initial anolyte pH adjustment can relieve the performance deterioration of the single-chamber air-cathode buffer-free microbial fuel cell (BFMFC) caused by anolyte acidification. Adjusting the initial anolyte pH to 9 in 5 running cycles is the optimum strategy. The relative abundance of the electrochemically active Geobacter in the KCl-pH9-MFC anode biofilm increased from 59.01% to 75.13% after the short-term adjustment. The maximum power density (Pmax) of the KCl-pH9-MFC was elevated from 316.4mW·m−2 to 511.6mW·m−2, which was comparable with that of the PBS-MFC. And, after the short-term adjusting, new equilibrium between the anolyte pH and the anode biofilm electrochemical activity has been established in the BFMFC, which ensured the sustainability of the improved bioelectricity generation performance.

Low-temperature hydrothermal pretreatment followed by dry anaerobic digestion: A sustainable strategy for manure waste management regarding energy recovery and nutrients availability

This study evaluated the feasibility of low-temperature hydrothermal (HT) pretreatment for improving dry anaerobic digestion (AD) of swine manure (SM) and nutrient elements reclamation, with specific goals to minimize the drawbacks of conventional HT process including high energy consumption, inhibitory compounds formation and unfavorable pH/alkalinity decrease. Pretreatment at 110–130°C for holding 30min increased the soluble organic carbon (SOC) concentration in SM by 13–26%. After being mixed with inocula, the pretreated SM was applied for dry AD tests successfully without initial pH adjustment, achieving a CH4 yield of 280.18–328.93ml/g-VSfed (14–34% increase compared to that from raw SM). Energy assessment indicated a positive net gain of 0.95kJ/g-VS by adopting HT pretreatment at 130°C. Except for increment in CH4 yield, low-temperature HT pretreatment also promoted organic-N mineralization, increasing N fractions in the digestate available for plants. After 70days’ dry AD, a high ammonia-N to total nitrogen (TN) ratio of 71% was obtained for the SM sample pretreated at 130°C, in sharp contrast to that of 38% in raw SM. P bioavailability in the final digestate was not greatly affected by the HT pretreatment since the labile organics were mostly degraded after AD, in which P existing forms were influenced by the multivalent metals content in SM. Overall, 23–27% of the total P was potentially bioavailable in all digestates.

Aerobic composting of distilled grain waste eluted from a Chinese spirit-making process: The effects of initial pH adjustment

Aerobic composting of distilled grain waste (DGW) at different initial pH values adjusted by CaO addition was investigated. Three pH-adjusted treatments with initial pH values of 4 (R1), 5 (R2) and 6 (R3) and a control treatment (R0) with a pH value of 3.5 were conducted simultaneously. The results showed that R0 had an unsuccessful start-up of composting. However, the pH-adjusted treatments produced remarkable results, with a relatively high initial pH being beneficial for the start-up. Within 65days of composting, the degradation of volatile solids (VS) and the physicochemical properties of R2 and R3 displayed similar tendencies, and both produced a mature end-product, while R1 exhibited a lower VS degradation rate, and some of its physicochemical properties indicated the end-product was immature. Quantitative PCR analysis of ammonia oxidizers indicated that the occurrence of nitrification during the composting of DGW could be attributed to the activity of ammonia-oxidizing bacteria.

Effects of different alkalis on hydrolysis of swine manure during dry anaerobic digestion and resultant nutrients availability

Hydrolysis is regarded as the rate-limiting step for dry anaerobic digestion (AD) of organic solid wastes. This study investigated the effect of different alkalis (Ca(OH)2, CaO, KOH and NaOH) on hydrolysis of swine manure during thermophilic dry AD at initial pH 10 and nutrients availability of the digestate by evaluating soluble organics production, hydrolase activity, nitrogen mineralization degree and phosphorus fractionation. Compared to their initial values, addition of Ca(OH)2 promoted the hydrolysis rate by 140% and enhanced volatile fatty acids (VFAs) production by 320%. Nitrogen mineralization was enhanced from 56% of control group to 64% when Ca(OH)2 was applied for initial pH adjustment, while decrease in P bioavailability was unavoidable. Both addition of NaOH and KOH achieved an increase around 250% on soluble total organic carbon (TOC) after 18 days’ fermentation, while little VFAs production and ammonia nitrogen were detected. In addition, the correlation between hydrolase activity and solid organics solubilization was also addressed. Further work is necessary to shed light on the mechanisms of dry AD after alkali addition to manure wastes.

Ozone-based advanced oxidation process as pre-treatment of wastewater from the wood-based industry

Three ozone-based advanced oxidation treatments (O3; O3 with initial pH adjustment and; O3/UV with initial pH adjustment) were compared for the treatment of a recalcitrant wastewater generated during washing/cleaning of surfaces and equipment used in filling and gluing processes (urea-formaldehyde and phenol-formaldehyde resins) in a wood-floor industry in Sweden. The wastewater (initial COD 3,400-4,000 mg/L) was obtained at the outlet of a sedimentation tank, which receive an inflow with an average COD of 45,000 mg/L. The experiments were performed in a semi-batch microbubble column reactor connected to a UV reactor, where 2.5 L samples of wastewater were submitted to the maximum dose of 2 g of O3 per gram of initial COD. For the full-factorial design, the independent variables were O3 concentration (g O3/Nm3); recirculation flow (L/min); and initial pH (pHi). The evaluation of the treatment performance was based on COD and TOC reductions (in %), and the effluent obtained was used in respirometric assays with activated sludge obtained at a municipal wastewater treatment plant to assess biodegradability/inhibitory effects. The results showed that ozonation at the original low pH promoted a reduction of 65% and 31% of COD and TOC respectively, but made the effluent less biodegradable. The highest COD and TOC reductions were achieved when O3 /UV treatment with pHi = 9.3 were applied (93% e 56% reductions for COD and TOC respectively). The results with the respirometry tests suggest that application of O3 only at higher pH values promoted biodegradability enhancement of the effluent, making it treatable by microbiota obtained with activated sludge from a municipal wastewater treatment plant.

Precise Tuning of Facile One-Pot Gelatin Methacryloyl (GelMA) Synthesis.

Gelatin-methacryloyl (GelMA) is one of the most commonly used photopolymerizable biomaterials in bio-applications. However, GelMA synthesis remains suboptimal, as its reaction parameters have not been fully investigated. The goal of this study is to establish an optimal route for effective and controllable GelMA synthesis by systematically examining reaction parameters including carbonate-bicarbonate (CB) buffer molarity, initial pH adjustment, MAA concentration, gelatin concentration, reaction temperature, and reaction time. We employed several analytical techniques in order to determine the degree of substitution (DS) and conducted detailed structural analysis of the synthesized polymer. The results enabled us to optimize GelMA synthesis, showing the optimal conditions to balance the deprotonation of amino groups with minimizing MAA hydrolysis, which led to nearly complete substitution. The optimized conditions (low feed ratio of MAA to gelatin (0.1 mL/g), 0.25 M CB buffer at pH 9, and a gelatin concentration of 10–20%) enable a simplified reaction scheme that produces GelMA with high substitution with just one-step addition of MAA in one pot. Looking forward, these optimal conditions not only enable facile one-pot GelMA synthesis but can also guide researchers to explore the efficient, high methacrylation of other biomacromolecules.

Kinetic modeling and dynamic simulation for the catalytic wet air oxidation of aqueous ammonia to molecular nitrogen

A kinetic model for the catalytic wet air oxidation of aqueous ammonia over Ru/TiO2 catalyst was developed considering the consecutive reaction steps as follows: (i) formation of active oxygen sites O* by the dissociative adsorption of aqueous O2 on the catalyst, (ii) oxidation of aqueous NH3 by the reaction with three O* sites to produce HNO2, (iii) aqueous phase dissociation of HNO2 into H+ and NO 2 − , (iv) formation of NH 4 + by the association of NH3 with the HNO2-dissociated H+, (v) formation of N2 by the aqueous phase reaction between NO 2 − and NH 4 + , (vi) formation of NO3 by the reaction of NO 2 − with an O* site. For each reaction step, a rate equation was derived and its kinetic parameters were optimized by experimental data fitting. Activation energies for the reactions (ii), (v), and (vi) were 123.1, 76.7, and 54.5 kJ/mol, respectively, suggesting that the oxidation reaction of aqueous NH3 to HNO2 was a ratedetermining step. From the simulation using the kinetic parameters determined, the initial pH adjustment of the ammonia solution proved to be critical for determining the oxidation product selectivity between desirable N2 and undesirable NO 3 − as well as the degree of oxidation conversion of ammonia.

MODELING OF ANAEROBIC CO-DIGESTION OF PIG MANURE AND DOMESTIC ORGANIC WASTE

The normal practice in Thailand is that the wastes from pig-farms and households are treated separately. Nutrient imbalance as well as other physico-chemical characteristics of each waste cause the anaerobic digestion process to work at suboptimal rates. This work is an attempt to describe the kinetics of anaerobic co-digestion of wastewater mixture from a pig-farm and domestic organic waste to understand the effect of their ratio on the biogas production efficiency in batch digesters which mimic a similar industrial practice. The batch experiments were carried out at three different temperatures (28 oC, 32oC and 35oC ), with and without initial pH adjustment (pH 7), and four levels of total solid (8%,12%,16% and 20% TS). It was found that the best operating condition was 35 oC, 16% TS and the pig-manure-to-domestic-waste ratio of 75:25. The modified Gompertz equation was used to estimate some Monod parameters and biomethane potential. Then modified two-substrate Monod equation was used to estimate the maximum specific biogas production rate (MBPR). It was also used to describe the microbial growth, substrate consumption and biogas production satisfactorily.

Impact of AC/O3 pretreatment on ultrafiltration processing sewage effluent for fouling alleviation

To resolve membrane fouling in the ultrafiltration process of sewage effluent, the impact of activated carbon catalytic ozonation (AC/O3) on fouling control was investigated. The influence of initial pH on AC/O3 for fouling alleviation was further explored. The results revealed that AC/O3 pretreatment greatly mitigated the membrane fouling. The total fouling, reversible fouling, and irreversible fouling were all decreased. The initial pH influenced the alleviation effect of AC/O3 on fouling control obviously, although it only slightly impacted the AC adsorption pretreatment on fouling alleviation. Besides, there was no obvious impact of pH on the ultrafiltration process. Compared with the adjustment of initial pH during ultrafiltration and the pretreatment methods such as AC adsorption and preozonation, AC/O3 displayed the greatest effect on both fouling alleviation and permeate quality improvement under all pH conditions. It was the component transformation of sewage effluent after AC/O3 pretreatment that caused the alleviation of membrane fouling. With the increase in initial pH, the high-MW biopolymers as well as humic substances in the effluent organic matter could be preferentially removed by AC/O3, which mitigated the flux decline during the ultrafiltration process and decreased the reversible and irreversible fouling.

Dual purpose recovered coagulant from drinking water treatment residuals for adjustment of initial pH and coagulation aid in electrocoagulation process

ABSTRACTThe present study is focused on the application of recovered coagulant (RC) by acidification from drinking water treatment residuals for both adjusting the initial pH and aiding coagulant in electrocoagulation. To do this, real cotton textile wastewater was used as a target pollutant, and decolorization and chemical oxygen demand (COD) removal efficiency were monitored. A preliminary test indicated that a stainless steel electrode combined with RC significantly accelerated decolorization and COD removal efficiencies, by about 52% and 56%, respectively, even at an operating time of 5 min. A single electrocoagulation system meanwhile requires at least 40 min to attain the similar removal performances. Subsequently, the interactive effect of three independent variables (applied voltage, initial pH, and reaction time) on the response variables (decolorization and COD removal) was evaluated, and these parameters were statistically optimized using the response surface methodology. Analysis of variance showed a high coefficient of determination values (decolorization, R2 = 0.9925 and COD removal, R2 = 0.9973) and satisfactory prediction second-order polynomial quadratic regression models. Average decolorization and COD removal of 89.52% and 94.14%, respectively, were achieved, corresponding to 97.8% and 98.1% of the predicted values under statistically optimized conditions. The results suggest that the RC effectively played a dual role of both adjusting the initial pH and aiding coagulant in the electrocoagulation process.

Oil refinery wastewater treatment using coupled electrocoagulation and fixed film biological processes

Oil refinery wastewater was treated using a coupled treatment process including electrocoagulation (EC) and a fixed film aerobic bioreactor. Different variables were tested to identify the best conditions using this procedure. After EC, the effluent was treated in an aerobic biofilter. EC was capable to remove over 88% of the overall chemical oxygen demand (COD) in the wastewater under the best working conditions (6.5 V, 0.1 M NaCl, 4 electrodes without initial pH adjustment) with total petroleum hydrocarbon (TPH) removal slightly higher than 80%. Aluminum release from the electrodes to the wastewater was found an important factor for the EC efficiency and closely related with several operational factors. Application of EC allowed to increase the biodegradability of the sample from 0.015, rated as non-biodegradable, up to 0.5 widely considered as biodegradable. The effluent was further treated using an aerobic biofilter inoculated with a bacterial consortium including gram positive and gram negative strains and tested for COD and TPH removal from the EC treated effluent during 30 days. Cell count showed the typical bacteria growth starting at day three and increasing up to a maximum after eight days. After day eight, cell growth showed a plateau which agreed with the highest decrease on contaminant concentration. Final TPHs concentration was found about 600 mgL−1 after 30 days whereas COD concentration after biological treatment was as low as 933 mgL−1. The coupled EC-aerobic biofilter was capable to remove up to 98% of the total TPH amount and over 95% of the COD load in the oil refinery wastewater.

Adsorption Removal of Environmental Hormones of Dimethyl Phthalate Using Novel Magnetic Adsorbent.

Magnetic polyvinyl alcohol adsorbent M-PVAL was employed to remove and concentrate dimethyl phthalate DMP. The M-PVAL was prepared after sequential syntheses of magnetic Fe3O4 (M) and polyvinyl acetate (M-PVAC). The saturated magnetizations of M, M-PVAC, and M-PVAL are 57.2, 26.0, and 43.2 emu g−1 with superparamagnetism, respectively. The average size of M-PVAL by number is 0.75 μm in micro size. Adsorption experiments include three cases: (1) adjustment of initial pH (pH0) of solution to 5, (2) no adjustment of pH0 with value in 6.04–6.64, and (3) adjusted pH0 = 7. The corresponding saturated amounts of adsorption of unimolecular layer of Langmuir isotherm are 4.01, 5.21, and 4.22 mg g−1, respectively. Values of heterogeneity factor of Freundlich isotherm are 2.59, 2.19, and 2.59 which are greater than 1, revealing the favorable adsorption of DMP/M-PVAL system. Values of adsorption activation energy per mole of Dubinin-Radushkevich isotherm are, respectively, of low values of 7.04, 6.48, and 7.19 kJ mol−1, indicating the natural occurring of the adsorption process studied. The tiny size of adsorbent makes the adsorption take place easily while its superparamagnetism is beneficial for the separation and recovery of micro adsorbent from liquid by applying magnetic field after completion of adsorption.

아로니아 막걸리의 안토시아닌 안정성

This study was conducted to investigate the effects of koji on the stability of anthocyanin pigments in aronia makgeolli. Adding a 12% amount of aronia was determined due to its feasible alcohol fermentation and color discrimination. Redness and total anthocyanin contents of sul-dut decreased with the fermentation period. In the nuruk group, adjustment of initial pH to 3.0, 3.5, and 4.5 resulted in higher redness and anthocyanin contents than nonpH adjustment at the initial fermentation period, whereas no significant differences in redness and anthocyanin contents were found between the two groups at the termination of fermentation. The ipguk group showed higher stability of pigments than the nuruk groups. The residual cyanidin-3-O-arabinoside of the ipkuk group was determined to be more than three times that of the nuruk groups. Furthermore, cyanidin-3-O-xyloside was only detected in the ipkuk group at the termination of fermentation. Therefore, it was thought that ipguk was a more suitable leavening agent than nuruk for the maintenance of anthocyanin stability on brewing of aronia makgeolli.

Studies on the in vitro cultivation of ciliate protozoa from the kangaroo forestomach

The methods used for culturing rumen protozoa were found to be unsatisfactory for growth of ciliate protozoa from the kangaroo forestomach. Based on published measurements of physical parameters in the marsupial forestomach, several modifications were incorporated into the procedure, i.e., an increase in % hydrogen in the gas phase, adjustment of initial pH of the medium to 6.9–7.0 range, feed only forage as a substrate and incubate at a lower temperature (33–36°C). Only incubation at the lower temperature increased survival time of the kangaroo protozoa. Two species of Bitricha were still viable after 28d in culture. Cultures had to be terminated at that time. One of the species differed considerably in size and shape from previously described species and based on 18S rRNA data, may represent a new species of Bitricha. The second species, present in low numbers was identified as Bitricha oblata. In a separate trial, Macropodinium yalanbense survived for 11d, at which time these cultures also had to be terminated.