Microbiological Degradation of Malodorous Substances of Swine Waste under Aerobic Conditions

Phenol, p-cresol, and volatile fatty acids (VFA; acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids) were used as odor indicators of swine waste. Aeration of the waste allowed the indigenous microorganisms to grow and degrade these malodorous substances. The time required for degradation of these substances varied according to the waste used, and it was not necessarily related to their concentrations. Using a minimal medium which contained one of the malodorous compounds as sole carbon source, we have selected from swine waste microorganisms that can grow in the medium. The majority of these microorganisms were able to degrade the same substrate when inoculated in sterilized swine waste but with an efficiency varying from one strain to the other. None of these strains was able to degrade all malodorous substances studied. Within 6 days of incubation these selected strains degraded the following: Acinetobacter calcoaceticus, phenol and all VFA; Alcaligenes faecalis, p-cresol and all VFA; Corynebacterium glutamicum and Micrococcus sp., phenol, p-cresol, and acetic and propionic acids; Arthrobacter flavescens, all VFA. On a laboratory scale, the massive inoculation of swine waste with C. glutamicum or Micrococcus sp. accelerated degradation of the malodorous substances. However, this effect was not observed with all of the various swine wastes tested. These results suggest that an efficient deodorization process of various swine wastes could be developed at the farm level based on the aerobic indigenous microflora of each waste.     

Biological Control of Hog Waste Odor through Stimulated Microbial Fe(III) Reduction

Odor control and disposal of swine waste have inhibited expansion of swine production facilities throughout the United States. Swine waste odor is associated primarily with high concentrations of volatile fatty acids (VFAs). Here, we demonstrate that stimulated Fe(III) reduction in hog manure can rapidly remove the malodorous compounds and enhance methane production by 200%. As part of these studies, we enumerated the indigenous Fe(III)-reducing population in swine waste and identified members of the family Geobacteraceae as the dominant species. These organisms were present at concentrations as high as 2 × 10⁵ cells g⁻¹. Several pure cultures of Fe(III) reducers, including Geobacter metallireducens, Geobacter humireducens, Geobacter sulfurreducens, Geobacter grbiciae, Geothrix fermentans, and Geovibrio ferrireducens, readily degraded some or all of the malodorous VFAs found in swine manure. In contrast, Shewanella algae did not degrade any of these compounds. We isolated an Fe(III) reducer, Geobacter strain NU, from materials collected from primary swine waste lagoons. This organism degraded all of the malodorous VFAs tested and readily grew in swine waste amended with Fe(III). When raw waste amended with Fe(III) was inoculated with strain NU, the VFA content rapidly decreased, corresponding with an almost complete removal of the odor. In contrast, the raw waste without Fe(III) or strain NU showed a marked increase in VFA content and a rapid pH drop. This study showed that Fe(III) supplementation combined with appropriate bioaugmentation provides a simple, cost-effective approach to deodorize and treat swine waste, removing a significant impediment to the expansion of pork production facilities.     

Microalgae-based processes for the biodegradation of pretreated piggery wastewaters

The potential and limitations of photosynthetic oxygenation on carbon and nitrogen removal from swine slurry were investigated in batch experiments using Chlorella sorokiniana and an acclimated activated sludge as model microorganisms. While algal-bacterial systems exhibited similar performance than aerated activated sludge in tests supplied with four and eight times diluted slurry, a severe inhibition of the biodegradation process was recorded in undiluted and two times diluted wastewater. Daily pH adjustment to 7 in enclosed algal-bacterial tests at several swine slurry dilutions allowed the treatment of up to two times diluted slurries (containing up to 1,180 mg N-NH(4) (+) l(-1)). The combination of high pH levels and high NH(4) (+) concentrations was thus identified as the main inhibitory factor governing the efficiency of photosynthetically oxygenated processes treating swine slurry. Measurements of soluble total organic carbon (TOC) and volatile fatty acids (VFA) present in the slurry suggested that VFA degradation (mainly acetic and propionic acid) accounted for most of the soluble TOC removal, especially during the initial stages of the biodegradation process. On the other hand, assimilation into biomass and nitrification to NO(2) (-) constituted the main NH(4) (+) removal processes in enclosed algal-bacterial systems.     

Volatile fatty acids production from food wastes and its application to biological nutrient removal

Korean food wastes were anaerobically digested to produce volatile fatty acids (VFA) that can be used as a carbon source in biological nutrient removal in a sequential batch reactor (SBR). Acetate, propionate and butyrate were produced at a yield of 379-400 g VFA/kg VS₀ (initial volatile solids). The ratio of SCOD (Soluble Chemical Oxygen Demand) of VFA to ammonia nitrogen (N) was in the range of 36.2-36.5 and the ratio of SCOD to phosphorus was between 151 and 162. The removal rate of nitrogen and phosphorus improved from 44% and 37% to 92% and 73%, respectively when the VFA were added to the influent of the Taejon municipal wastewater plant. The concentration of nitrogen and phosphorus were maintained below 3 mg/l and 1 mg/l, respectively. The N- and P-content of the food waste was low enough not to influence the final N- and P-concentrations of the wastewater.     

Phosphate Release and Uptake by Pure Cultures of Acinetobacter sp.: Effect of the Volatile Fatty Acids Concentration

Phosphorus release and uptake by pure cultures of Acinetobacter strains were investigated under anaerobic and aerobic conditions respectively. Tests were performed to study the relationship between phosphorus release-storage reaction and behavior of extracellular organic substrates: acetic, propionic, and butyric acids have been used at four concentrations (50, 100, 500, and 1000 mg · L⁻¹) in the anaerobic step of biological phosphorus removal. The results obtained depend on the strain and the volatile fatty acid (VFA) used. Phosphorus released under anaerobic condition was not always related to the amount of VFA or phosphorus consumed. Phosphorus uptake (P-uptake) in the aerobic step was found to be independent of phosphorus release rates. The best phosphorus uptake rates were obtained by Acinetobacter lwoffi ATCC21130 and Acinetobacter calcoaceticus Genoespecie SUCT-5 with butyric acid as carbon source. Received: 20 May 1996 / Accepted: 8 July 1996     

Performance of microbial fuel cell with volatile fatty acids from food wastes

Food wastes were used as feedstock for the direct production of electricity in a microbial fuel cell (MFC). MFC operations with volatile fatty acids (VFA) produced 533 mV with a maximum power density of 240 mW/m². Short-chain VFAs, such as acetate, were degraded more rapidly and thus supported higher power generation than longer chain ones. In general, the co-existence of other, different VFAs slowed the removal of each VFA, which indicated that anodic microbes were competing for different substrates. 16S rRNA gene analysis using PCR-DGGE indicated that the MFC operation with VFAs had enriched unique microbial species.     

Growth monitoring of <Emphasis Type="Italic">Fibrobacter succinogenes</Emphasis> by pressure measurement

In life support systems, such as the MELiSSA (Micro-Ecological Life Support Alternative) project, developed by the European Space Agency, the aim is to understand and assemble artificial ecosystems for ensuring human subsistence in space. Fibrobacter succinogenes, an anaerobic bacterium, was used for the degradation of vegetable wastes produced in higher plants chambers, but the process does not allow the monitoring of biomass concentration and degradation rates. This study proposes a growth and a degradation monitoring technique using pressure measurements. First, volatile fatty acids (VFA) production was compared with biomass growth and with CO₂ production. The experiments were carried out in batch and fed-batch processes on glucose and on vegetables. The results have shown that a link could be established between VFA production, degradation rate and gas pressure measurements. Thus, the pressure could be used both as a relevant variable for online evaluation of biomass growth and of degradation of complex vegetable wastes.     

Growth of Candida ingens on Supernatant from Anaerobically Fermented Pig Waste: Effects of Temperature and pH

Candida ingens, a pellicle-forming yeast utilizing volatile fatty acids, grew over a pH range of 4.1 to 6.0 on nonsterile supernatants from anaerobically fermented pig wastes; growth was inconsistent between pH 4.1 and 4.6. When ambient temperature above the pellicle was 21°C and the temperature of the medium was 29 to 32°C, a pH range of 4.8 to 5.0 gave yields of 1.90 to 3.31 g of dry matter per liter, and 0.059 to 0.065 mol of volatile fatty acids was utilized per liter. There was no advantage in utilization of volatile fatty acids and yield of dry matter in keeping the pH constant during a 24-h growth period. C. ingens grew at pH 4.8 and 5.0 when both ambient and medium temperatures were 30°C. When ambient temperature was 10°C, maximum yield and utilization of volatile fatty acids occurred at a medium temperature of 28 to 30°C.     

Carbohydrate fermentation and by-product absorption studied with labelled cellulose in Oryctes nasicornis larvae (Coleoptera:Scarabaeidae)

Isolated gut segments of Oryctes nasicornis larvae were incubated in vitro after injection with ¹⁴C-cellulose. The incubation medium became progressively richer in labelled volatile fatty acids (VFA), demonstrating the process of cellulolysis and the absorption of carbohydrate degradation products. The mesenteron and the proctodeal dilation were both shown to be sites of cellulolysis and VFA absorption. The major acid formed and absorbed was acetic acid which, in the absence of any detectable glucose, would seem to constitute the essential product of carbon metabolism in Oryctes larvae as in ruminant mammals. The cellulolytic capacities of the different intestinal segment were tested and compared to each other.     

Branched chain amino acids as source of specific branched chain volatile fatty acids during the fermentation process of fish sauce

Summary.  The source of the formation of branched chain volatile fatty acids (VFA) in fish sauce was investigated. Certain branched VFA were derived from the degradation of specific amino acids as iso-butyric acid from valine and iso-valeric acid from leucine. Short and long straight chain VFA were significantly higher in the linoleic acid added sample than in the control but did not significantly bring changes to the branched chain VFA. It is suggested that straight chain VFA developed from fish fats. Alanine and isoleucine did not have a clear influence on the production of volatile fatty acids. Received November 23, 2001 Accepted June 20, 2002 Published online December 18, 2002 RID="*" ID="*" Part of this paper was presented in the 7th International Congress on Amino Acids and Proteins in Vienna, Austria from August 6–10, 2001. Authors' address: Norlita G. Sanceda, Ph.D., Institute of Environmental Science for Human Life, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112, Japan, Fax: + 81-3-5978-5805, E-mail: lita@cc.ocha.ac.jp     

Eugenol stimulates lactate accumulation yet inhibits volatile fatty acid production and eliminates coliform bacteria in cattle and swine waste

AIM: To determine how eugenol affects fermentation parameters and faecal coliforms in cattle and swine waste slurries stored anaerobically. METHODS AND RESULTS: Waste slurries (faeces:urine:water, 50:35:15) were blended with and without additives and aliquoted to triplicate 1-l flasks. Faecal coliforms were eliminated in cattle and swine waste slurries within 1 or 2 days with additions of eugenol at 10.05 mm (0.15%) and 16.75 mm (0.25%). At these concentrations volatile fatty acids (VFA) were reduced ca 70 and 50% in cattle and swine waste, respectively, over 6-8 weeks. Additionally, in cattle waste, eugenol stimulated the accumulation of lactate (>180 mm) when compared with thymol treatment (20 mm lactate). In swine waste, lactate accumulation did not occur without additives; eugenol and thymol stimulated lactate accumulation to concentrations of 22 and 32 mm, respectively. CONCLUSIONS: Eugenol added to cattle waste may be more beneficial than thymol because not only does it effectively control faecal coliforms and odour (VFA production), it also stimulates lactate accumulation. This in turn, causes the pH to drop more rapidly, further inhibiting microbial activity and nutrient emissions. SIGNIFICANCE AND IMPACT OF THE STUDY: Plant essential oils have the potential to solve some of the environmental problems associated with consolidated animal feeding operations. Thymol and eugenol reduce fermentative activity, thus, have the potential to reduce emissions of greenhouse gases and odour, and curtail transmission of pathogens in cattle and swine wastes.     

Detection of Industrial Pollutants and Toxic Chemical Wastes in Sewage Treatment Plant Influents by Use of a Biological Monitor

Heterogeneous mixtures of toxic chemical wastes affecting the normal operations of a sewage treatment facility employing anaerobic digestion were detected by dark-field observation of uncoordinate flagellar orientation patterns displayed by cells of Spirillum volutans. These results were compared with plant parameters determined by gas production, volatile fatty acids, and alkalinity measurements.     

Mortality of Pratylenchus penetrans by Volatile Fatty Acids from Liquid Hog Manure

As part of our research program assessing the use of liquid hog manure (LHM) to control root-lesion nematodes, Pratylenchus penetrans, a series of acute toxicity tests was conducted to: (i) examine if non-ionized forms of volatile fatty acids (VFA) are responsible for the mortality of P. penetrans exposed to LHM under acidic conditions, (ii) determine if Caenorhabditis elegans can be a surrogate for P. penetrans in screening tests by comparing their sensitivities to VFA, (iii) characterize the nematicidal effect of individual VFA in LHM to P. penetrans, and (iv) determine whether individual VFA in LHM interact in their toxicity to P. penetrans. LHM was significantly (P ≤ 0.05) more toxic to P. penetrans than a mixture of its main VFA components at concentrations of 5% and 10% (vol. VFA or LHM /vol. in buffer). Pratylenchus penetrans was more sensitive to acetic acid than C. elegans, whereas the sensitivity of both nematode species to n-caproic acid was similar. Individual VFA vary in their lethality to P. penetrans. n-valeric acid was the most toxic (LC₉₅= 6.8 mM), while isobutyric acid was the least toxic (LC₉₅ = 45.7 mM). Individual VFA did not interact in their toxicity to P. penetrans, and their effects were considered additive. VFA account for the majority of the lethal effect of LHM to P. penetrans under acidic conditions. Caenorhabditis elegans cannot be used as a surrogate to P. penetrans in toxicity studies using VFA. The efficacy of LHM to control P. penetrans can be evaluated by assessing its VFA content prior to application, and this evaluation is facilitated by the fact that the interaction of individual VFA appears to be simply additive.     

Factors affecting the survival of Salmonella and Escherichia coli in anaerobically fermented pig waste

The survival of Salmonella typhimurium was investigated in acidogenic, anaerobically fermented pig wastes and in synthetic media, each containing volatile fatty acids (VFA). Salm. typhimurium survived at pH 6.8, but not at pH 4.0, when incubated at 37 degrees C for 24 h in either fermented or synthetic medium containing VFA. The minimum inhibiting concentration of VFA for Salm. typhimurium after 48 h incubation at 30 degrees C at pH 4.0 was 0.03 mol/l and for Escherichia coli it was 0.09 mol/l. Fermented pig wastes in a digester, maintained at pH 5.9, were inoculated with Salm. typhimurium and then incubated at 37 degrees C for 24 h. The pH was adjusted to either 4.0 or 5.0 and after a further 48 h at 30 degrees C, Salm. typhimurium survived at pH 5.0 but not at pH 4.0. It was concluded that pH is critical in determining the survival of this organism in acidogenic anaerobically fermented pig waste.     

Factors affecting the survival of Salmonella and Escherichia coli in anaerobically fermented pig waste

The survival of Salmonella typhimurium was investigated in acidogenic, anaerobically fermented pig wastes and in synthetic media, each containing volatile fatty acids (VFA). Salm. typhimurium survived at pH 6·8, but not at pH 4·0, when incubated at 37°C for 24 h in either fermented or synthetic medium containing VFA. The minimum inhibiting concentration of VFA for Salm. typhimurium after 48 h incubation at 30°C at pH 4·0 was 0·03 mol/l and for Escherichia coli it was 0·09 mol/l. Fermented pig wastes in a digester, maintained at pH 5·9, were inoculated with Salm. typhimurium and then incubated at 37°C for 24 h. The pH was adjusted to either 4·0 or 5·0 and after a further 48 h at 30°C, Salm. typhimurium survived at pH 5·0 but not at pH 4·0. It was concluded that pH is critical in determining the survival of this organism in acidogenic anaerobically fermented pig waste.     

Production of volatile fatty acids from bagasse by rumen bacteria

Summary Conditions are described for converting bagasse lignocellulose to volatile fatty acids (VFA) by anaerobic fermentation. Although yields of VFA were as high as 74% by weight of digestible organic matter (or 54% of dry bagasse), limitations were imposed by both fermenter design and fibre digestibility. All fermentations were substrate-limited up to the maximum initial concentration examined of 50 g bagasse · l^-1 and no product inhibition was evident (up to 260 mM VFA produced). Maximum VFA productivities of 0.25 to 0.65 g · l^-1 · h^-1 were obtained in batch fermentations and this is greater than those previously reported using lignocellulosic substrates. Batch fermentations neared completion after 66 h.     

Influence of Environmental Conditions on Methanogenic Compositions in Anaerobic Biogas Reactors

The influence of environmental parameters on the diversity of methanogenic communities in 15 full-scale biogas plants operating under different conditions with either manure or sludge as feedstock was studied. Fluorescence in situ hybridization was used to identify dominant methanogenic members of the Archaea in the reactor samples; enriched and pure cultures were used to support the in situ identification. Dominance could be identified by a positive response by more than 90% of the total members of the Archaea to a specific group- or order-level probe. There was a clear dichotomy between the manure digesters and the sludge digesters. The manure digesters contained high levels of ammonia and of volatile fatty acids (VFA) and were dominated by members of the Methanosarcinaceae, while the sludge digesters contained low levels of ammonia and of VFA and were dominated by members of the Methanosaetaceae. The methanogenic diversity was greater in reactors operating under mesophilic temperatures. The impact of the original inoculum used for the reactor start-up was also investigated by assessment of the present population in the reactor. The inoculum population appeared to have no influence on the eventual population.     

Identification and Characteristics of Actinomycetes Useful for Semicontinuous Treatment of Domestic Animal Feces

Selected strains of actinomycetes useful for practicing semicontinuous treatment of swine and poultry feces were identified as Streptomyces antibioticus S-4, S. puniceus N-50-2, S. nigrifaciens N-9-3, Thermoactinomyces vulgaris HIR-60, and Thermomonospora viridis HIR-50. These five obligately aerobic strains grew preferably on nonsterilized fresh swine feces in 24 h without any additives. They assimilated offensive volatile fatty acids in the swine and poultry feces. Cultures of these five strains were mixed and used as seed for the practical treatments of 1 ton of swine feces over the wide temperature range of 15 to 60°C. Strain HIR-50 grew most predominantly on both fresh swine and poultry feces at 50 to 55°C and decomposed uric acid. For the efficient penetration of mycelia into the feces, manures were mixed once a day so as not to break the solid mass, and the dehydration rate of feces had to be controlled in proportion to the mycelial growth rate. The actinomycete biofertilizer thus manufactured in 10 days was odorless and promotive of plant growth.     

Identification of crude-oil components and microorganisms that cause souring under anaerobic conditions

Oil souring has important implications with respect to energy resources. Understanding the physiology of the microorganisms that play a role and the biological mechanisms are both important for the maintenance of infrastructure and mitigation of corrosion processes. The objective of this study was to identify crude-oil components and microorganisms in oil-field water that contribute to crude-oil souring. To identify the crude-oil components and microorganisms that are responsible for anaerobic souring in oil reservoirs, biological conversion of crude-oil components under anaerobic conditions was investigated. Microorganisms in oil field water in Akita, Japan degraded alkanes and aromatics to volatile fatty acids (VFAs) under anaerobic conditions, and fermenting bacteria such as Fusibacter sp. were involved in VFA production. Aromatics such as toluene and ethylbenzene were degraded by sulfate-reducing bacteria (Desulfotignum sp.) via the fumarate-addition pathway and not only degradation of VFA but also degradation of aromatics by sulfate-reducing bacteria was the cause of souring. Naphthenic acid and 2,4-xylenol were not converted.     

Straw- and slurry-associated prokaryotic communities differ during co-fermentation of straw and swine manure

Anaerobic co-fermentation of straw and manure is widely used for waste treatment and biogas production. However, the differences between the straw- and slurry-associated prokaryotic communities, their dynamic changes throughout the co-fermentation process, and their correlations with bioreactor performance are not fully understood. To address these questions, we investigated the prokaryotic community compositions and the dynamics of prokaryotes attached to the straw and in the slurry during co-fermentation of wheat straw and swine manure using pyrosequencing technique. The results showed that straw- and slurry-associated prokaryotes were different in their structure and function. Straw-associated prokaryotic communities were overrepresented by the phyla Spirochaetes and Fibrobacteres, while Synergistetes and Euryarchaeota were more abundant in the slurry. The straw-associated candidate class TG3, genera Fibrobacter, Bacteroides, Acetivibrio, Clostridium III, Papillibacter, Treponema, Sedimentibacter, and Lutispora may specialize in substrate hydrolysis. Propionate was the most abundant volatile fatty acid in the slurry, and it was probably degraded through syntrophic oxidation by the genera Pelotomaculum, Methanoculleus, and Methanosaeta. The protein-fermenting bacteria Aminobacterium and Cloacibacillus were much abundant in the slurry, indicating that proteins are important substrates in the co-fermentation. This study provided a better understanding of the anaerobic co-fermentation process that is driven by spatially differentiated microbiota.