Biomethanation of cheese whey using anaerobic upflow fixed film reactor

Performance of anaerobic upflow fixed film reactors for biomethanation of high-strength cheese whey using different support material such as charcoal, gravel, brick pieces, PVC pieces and pumice stones at 37°C has been studied. Among them the charcoal fixed film reactor showed the best performance when operated at 2 d hydraulic retention times (HRT), achieving maximum COD removal of 81% (COD influent=70 g/l) and improved total gas production (6.7 l/d/l digester) with high methane content (72%).     

Anaerobic digestion of cheese whey using an upflow anaerobic sludge blanket reactor: III. Sludge and substrate profiles

Anaerobic treatment of cheese whey using a 17·5 litre upflow anaerobic sludge blanket reactor was investigated in the laboratory over a range of influent concentration from 4·5 to 38·1 g COD litre⁻¹ at a constant hydraulic retention time of 5 days. The results indicated that two sludge distribution regions, a sludge bed and a sludge blanket, as well as two distinct reaction phases, acidogenic and methanogenic, were formed. However, as the substrate loading was increased, the acidogenic region extended into the methanogenic region in the upper portion of the reactor until the whole region was acidogenic, leading to the failure of the reactor.     

Anaerobic digestion of cheese whey using up-flow anaerobic sludge blanket reactor

Anaerobic treatment of cheese whey using a 17·5-litre up-flow anaerobic sludge blanket reactor was investigated in the laboratory. The reactor was studied over a range of influent concentration from 4·5 to 38·1 g chemical oxygen demand per litre at a constant hydraulic retention time of 5 days. The reactor start-up and the sludge acclimatization were discussed. The reactor performance in terms of methane production, volatile fatty acids conversion, sludge net growth and chemical oxygen demand reduction were also presented in this paper. Over 97% chemical oxygen demand reduction was achieved in this experiment. At the influent concentration of 38·1 g chemical oxygen demand per litre, an instability of the reactor was observed. The results indicated that the up-flow anaerobic sludge blanket reactor process could treat cheese whey effectively.     

Cotton yarn and fabric finishing wastewater treatment in upflow anaerobic filter

Summary Wastewater from cotton yarn and fabric finishing was successfully treated in an upflow anaerobic filter at 35°C up to a COD loading of 1 Kgr COD/m³ · day; the COD removal varied from 50 to 90% and production of biogas was 0,2–0.4 L/g influent COD, having 70–80% CH₄. At higher COD loading biogas production stopped although COD removal remainedca 50%.     

Cotton fabric desizing and scouring wastewater treatment in upflow anaerobic filter

Summary Wastewater from textile desizing and scouring was successfully treated in an upflow anaerobic filter at 35°C; the COD loading waas gradually increased up to 2.75 kg/m³day with COD removal of 60–90%, and production of 0.2–0.5 L gas/g. influent COD, having 75–80% CH₄.     

Anaerobic digestion of wood ethanol stillage using upflow anaerobic sludge blanket reactor

The anaerobic digestion of wood ethanol stillage in a UASB reactor was studied. At organic loading rates be low 16 kg COD/m(3) day the reactor performed effectively, achieving soluble COD and BOD removals in excess of 86 and 93%, respectively. Removal of color averaged 40%. At a loading rate of 16 kg COD/m(3) day the methane yield was 0.302 L CH(4) (STP)/g COD removed, and the observed cell yield was 0.112 g VSS/g COD removed. Operation of the reactor at higher loading rates was unsuccessful. Nitrogen, phosphorus, and alkalinity were supplemented. No additions of the essential trace elements Fe, Co, and Ni were required.     

Semi-continuous anaerobic digestion of a food industry wastewater in an anaerobic filter

The experimental results of semi-continuous tests of anaerobic digestion of confectionery industry wastewater, carried out at different residence times and organic loads in an upflow anaerobic filter, are presented and discussed. Giving COD removals higher than 80% under the whole range of conditions tested, the anaerobic filter demonstrated not only a great ability of biomass to adapt itself to a new carbon source but also an excellent capability to deal with organic load fluctuations and to utilise dilute feeds. Sampling at different filter heights demonstrated that the biogas development ensured mixing within the filter and that most of the organic substances were utilised at the bottom of the reactor, especially when very dilute wastewater was fed. The results of this work could be taken as a starting basis for scaling-up the process to the industrial scale.     

Anaerobic digestion of a petrochemical effluent using an upflow anaerobic sludge blanket reactor

Summary An UASB reactor was used for the anaerobic conversion of an acidic petrochemical effluent into a methane-rich biogas. Reactor efficiency was optimal at an HRT of 1.78 days and loading rate of 7.255 kg COD/m₃.d, A COD reduction of 83% was obtained. The gas production was 2.64 m/m .d (STP) and contained more than 90% CH₄. A further increase in the loading rate resulted in a drastic decrease in the reactor effectivity.     

Performances of a full-scale novel multiplate anaerobic reactor treating cheese whey effluent

A 450-m(3) multiplate anaerobic reactor (MPAR) has been started-up in April 1992 for treating wastewater (whey permeate and domestic wastewater) at the Nutrinor (Lactel) cheese factory in Chambord (Québec, Canada). The MPAR consists of four superimposed sections. The liquid flows upwards from one section to the next, while the gas is collected below each plate and evacuated through side-outlets. The wastewater is concurrently distributed at the bottom of the first, second, and third sections, as 50%, 33%, and 17% of the total influent stream, respectively. Granular anaerobic sludge at an initial concentration of 30 kg of volatile suspended solids (VSS) per cubic meter of reactor liquid volume was used to inoculate the reactor. Under normal operation of the factory, the chemical oxygen demand (COD) concentration of the influent ranged from 20 to 37 kg COD m(-3). The reactor organic loading rate (OLR) fluctuated between 9 and 14.7 kg COD m(-3) d(-1) for hydraulic retention times (HRT) maintained between 55 and 68 h. At the highest OLR, the MPAR showed an efficiency of 98% and 92% for soluble and total COD removal, respectively, and a methane production rate averaging around 4 m(3) m(-3) d(-1).Biomass-specific activities ranged between 7 and 51, 1.3 and 8.5, 5.3 and 12.2, 60 and 119, and 119 and 211 mmol g(-1) VSS d(-1) for glucose, propionate, acetate, formate, and hydrogen, respectively. Average equivalent-diameter of the granules was around 0.65 mm. The MPAR reactor generally showed a large capacity for solid retention with a biomass content between 32 and 37 kg VSS m(-3). (c) 1995 John Wiley & Sons, Inc.     

Continuous propionic acid production from cheese whey usingin situ spin filter

The potential use of spin filter device to retainPropionibacterium acidipropionici in the bioreactor under continuous mode of fermentation and improve propionic acid productivity, was examined. The yield of propionic acid based on lactose concentration was 51% in batch and 54% in continuous (dilution rate=0.05 h⁻¹) operation. The yield in continuous fermentation with cell retention using spin filter of 10 micron size (dilution rate=0.05 h⁻¹) was even higher at 70% (w/w). The volumetric productivity under batch and continuous mode of operation were 0.312 g L⁻¹ h⁻¹ and 0.718 g L⁻¹ h⁻¹ respectively. Continuous fermentation with cell retention demonstrated even higher volumetric productivities at 0.98 g L⁻¹ h⁻¹ with out clogging problems It could be used for utilization of cheese whey to produce propionic acid at higher yield and productivities.     

Anaerobic digestion of high-strength cheese whey utilizing semicontinuous digesters and chemical flocculant addition

Semicontinuous digesters were used to anaerobically treat high-strength whey (70 kg/m(3).COD). A maximum loading of 16.1 kg COD/m(3).day was obtained with soluble COD removal efficiencies greater than 99%. The use of a chemical flocculant resulted in an increased biomass concentration in the digester compared to a control, thus enabling correspondingly higher space loadings to be applied. With the onset of substantial levels of granulation of the biomass, flocculant dosage was able to be discontinued. This article discusses the performance of the digesters in detail and, briefly, the long-term operational difficulties experienced and the control strategies employed on such systems.     

Fault detection filter design for an anaerobic digestion process

In this paper, a Fault Detection and Isolation observer based method has been applied to biological wastewater treatment process. The method is designed with a dynamic model and the observer is determined using the eigenstructure assignment approach. The efficiency of the method is demonstrated for both detection and isolation of an actuator and a sensor failure using experimental data from a pilot scale anaerobic digestion process for the treatment of an industrial wine distillery vinasses.     

Microbiological aspects of anaerobic digestion of swine slurry in upflow fixed-bed digesters with different packing materials

Samples taken from liquid influents, liquid effluents, bottom sediments and biofilms attached to the supports of three laboratory anaerobic, fixed-bed, upflow digesters, filled with wood chips, PVC or expanded-clay support media and fed with swine slurry, were tested microbiologically. The numbers of anaerobic heterotrophic, anaerobic cellulolytic, acidogenic-peptone-glucose fermenting and methanogenic bacteria were determined. For each digester the biogas production was monitored.The highest biogas production, referred to the volatile solids concentration in the feed, was obtained in the digester with wood chips, while production was almost nil in the digester with expanded clay.     

Conversion of cheese whey to single-cell protein

Thirteen yeast species belonging to nine genera were screened for the production of single-cell protein (SCP) using cheese whey as the substrate. Cheese whey supplemented with minerals and yeast extract proved to the best medium for yield, lactose utilization, biomass production, and conversion efficiency. Production of beta-galactosidase was studied in Brettanomyces anomalus, Kluyveromyces fragilis, Trichosporon cutaneum, and Wingea robertsii; the last proved to be the best strain combining high yield with shorter incubation period.     

Two-stage anaerobic digestion of biodegradable municipal solid waste using a rotating drum mesh filter bioreactor and anaerobic filter

A rotating drum mesh filter bioreactor (RDMFBR) with a 100 μm mesh coupled to an anaerobic filter was used for the anaerobic digestion of biodegradable municipal solid waste (BMW). Duplicate systems were operated for 72 days at an organic loading rate (OLR) of 7.5 gVS l⁻¹ d⁻¹. Early in the experiment most of the methane was produced in the 2nd stage. This situation gradually reversed as methanogenesis became established in the 1st stage digester, which eventually produced 86–87% of the total system methane. The total methane production was 0.2 l g⁻¹ VS_added with 60–62% volatile solids destruction. No fouling was experienced during the experiment at a transmembrane flux rate of 3.5 l m⁻² h⁻¹. The system proved to be robust and stably adjusted to a shock loading increase to 15 gVS l⁻¹ d⁻¹, although this reduced the overall methane production to 0.15 l g⁻¹ VS_added.     

Thermal and enzymatic pretreatment of sludge containing phthalate esters prior to mesophilic anaerobic digestion

The present study aimed at investigating the effect of thermal pretreatment of sludge at 70 degrees C on the anaerobic degradation of three commonly found phthalic acid esters (PAE): di-ethyl phthalate (DEP), di-butyl phthalate (DBP), and di-ethylhexyl phthalate (DEHP). Also, the enzymatic treatment at 28 degrees C with a commercial lipase was studied as a way to enhance PAE removal. Pretreatment at 70 degrees C of the sludge containing PAE negatively influenced the anaerobic biodegradability of phthalate esters at 37 degrees C. The observed reduction of PAE biodegradation rates after the thermal pretreatment was found to be proportional to the PAE solubility in water: the higher the solubility, the higher the percentage of the reduction (DEP > DBP > DEHP). PAE were slowly degraded during the pretreatment at 70 degrees C, yet this was probably due to physicochemical reactions than to microbial/biological activity. Therefore, thermal pretreatment of sludge containing PAE should be either avoided or combined with a treatment step focusing on PAE reduction. On the other hand, enzymatic treatment was very efficient in the removal of PAE. The enzymatic degradation of DBP, DEP, and DEHP could be one to two orders of magnitude faster than under normal mesophilic anaerobic conditions. Moreover, the enzymatic treatment resulted in the shortest half-life of DEHP in sludge reported so far. Our study further showed that enzymatic treatment with lipases can be applied to raw sludge and its efficiency does not depend on the solids concentration.     

Layered structure of bacterial aggregates produced in an upflow anaerobic sludge bed and filter reactor

The ultrastructure of bacterial granules that were maintained in an upflow anaerobic sludge bed and filter reactor was examined. The reactor was fed a sucrose medium, and it was operated at 35 degrees C. Scanning and transmission electron microscopy revealed that the granular aggregates were three-layered structures. The exterior layer of the granule contained a very heterogeneous population that included rods, cocci, and filaments of various sizes. The middle layer consisted of a slightly less heterogeneous population than the exterior layer. A more ordered arrangement, made up predominantly of bacterial rods, was evident in this second layer. The third layer formed the internal core of the granules. It consisted of large numbers of Methanothrix-like cells. Large cavities, indicative of vigorous gas production, were evident in the third layer. On the basis of these ultrastructural results, a model that presents a possible explanation of granule development is offered.     

Production of vitamin B12 in an upflow anaerobic filter continuous reactor using Acetobacterium sp.

The accumulation of biofilm by Acetobacterium sp. during continuous culture in an upflow anaerobic filter (UAF) growing on methanol-formate was the result of space velocity and inlet concentrations of substrate and Co⁺². To achieve good development of biofilm, a space velocity of 0.38 h^–1, inlet substrate concentrations of 125 mM of both methanol and formate, and Co⁺² at 0.16 mM were required. Cell productivities in the effluent of the UAF-reactor were about 6-fold higher than in chemostat cultures (0.20 g l^–1 h^–1 for UAF and 0.035 g l^–1 h^–1 for chemostat) (previous studies), and the maximum vitamin B₁₂ specific concentration was 5.1 mg g cell^–1.     

Layered structure of bacterial aggregates produced in an upflow anaerobic sludge bed and filter reactor.

The ultrastructure of bacterial granules that were maintained in an upflow anaerobic sludge bed and filter reactor was examined. The reactor was fed a sucrose medium, and it was operated at 35 degrees C. Scanning and transmission electron microscopy revealed that the granular aggregates were three-layered structures. The exterior layer of the granule contained a very heterogeneous population that included rods, cocci, and filaments of various sizes. The middle layer consisted of a slightly less heterogeneous population than the exterior layer. A more ordered arrangement, made up predominantly of bacterial rods, was evident in this second layer. The third layer formed the internal core of the granules. It consisted of large numbers of Methanothrix-like cells. Large cavities, indicative of vigorous gas production, were evident in the third layer. On the basis of these ultrastructural results, a model that presents a possible explanation of granule development is offered.