TGGE-monitoring of the microbial community along the olive mill wastewaters anaerobic treatment

Monitoring the microbial community present during the olive mill wastewater (OMW) anaerobic treatment was carried out using PCR-TGGE analysis. Phase-contrast microscopy was used in order to directly examine microbial cells morphology. Samples were collected from the anaerobic digester bottom along the successive increases of OMW loading rate. TGGE banding patterns showed a significant diversity of OTUs. Cluster analysis of TGGE banding patterns shows two major groups: one cluster composed of samples belonging to the initial phases of treatment and a second cluster that encloses the other two samples. According to BLAST results, four sequences affiliated with group Cytophaga-Flexibacter-Bacteroidetes (CFB), one with sub-class Epsilon-Proteobacteria and other with phylum Firmicutes. The sequences obtained from each band were used to construct phylogenetic trees, and also using bacterial 16S rDNA sequences from environmental clones and reference taxa. Archaeal 16SrDNA PCR detection analysis revealed the presence of Archaea only in the initial sample of the digester start-up suggesting that methanogenesis along the treatment process occurs at an upper level of the unit. Concerning microscopic observations, the more representative morphological forms found in the bottom of digester were Clostridium spp. and Clostridium spp. sarcina-like forms

Ethanol production from enzymatically pretreated wheat straw

Lignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. Wheat straw is an abundant agricultural residue which can be used as lignocellulosic raw material for bioconversion. There are mainly two processes involved in the bioconversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The current study involved the optimization of enzymatic hydrolysis of a wheat straw pretreated by acid hydrolysis, using a mixture of commercial cellulases: celluclast 1.5L + Novozym 188, with further fermentation of the hydrolisate’ sugar content by three ethanologenic strains, namely two yeast of Saccharomyces cerevisiae (strains F and K) and a bacterial strain, Zymomonas mobilis (strain CP4). The fermentation assays, using undiluted hydrolisate with or without nutrient supplements, were monitored by the evaluation of glucose and ethanol yields. In the assays using no supplemented hydrolisate the results obtained for the two yeasts strains F and K, and Zymomonas mobilis were 74%, 79% and 58% of ethanol yield, respectively. However, when the hydrolisate was supplemented the fermentation results showed a better bioconversion process by the Z. mobilis, reaching 98% ethanol yield while the two strains of S. cerevisiae used maintained their behaviour. So, the fermentation results showed the necessity of the addition of nutrients for a good bioconversion process by the Z. mobilis, resulting in better ethanol yield than S. cerevisiae strains (F and K) from WSP hydrolisate

Kinetics of a packed-bed bacth reactor for the treatment of olive oil wastewaters from a Portuguese mill

Olive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater. This effluent does not undergo any treatment and is usually stored in evaporation lagoons or spread on the land. This can have a negative impact in the environment since this effluent has a high level of organic matter leading to a high chemical oxygen demand. In addition it has also a high content of polyphenols that contributes to the ecotoxicity of this effluent.Different techniques for the treatment of these wastewaters have been studied. In this work a 60 litre vessel was filled with a packaging of plastic material consisting of a cubic geometry (Biological Carrier Media from Rauschert). The non-inoculated reactor was filled with effluent from an olive mill farm (from Alfândega da Fé, Trás-os-Montes) and the effluent was re-circulated daily for homogeneity. COD, colour, nitrogen, solids and phosphorous were measured to follow the evolution of the system. Microbial composition and polyphenols were also evaluated. As an indicator of the microbial activity in the reactor, lipase activities were measured. Ecotoxicity tests were carried out to follow the detoxification capacity of the system as well as its potential for using in the treatment of this type of agroindustrial effluent

Olive Mill wastewater bioremediation towards detoxification

Olive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater (OMW), which does not undergo any treatment and, usually, is stored in evaporation lagoons or spread on the land. Disposal of olive oil mill wastewaters is a serious environmental problem due to its high organic loading, presence of polyphenols and tannins, high content in suspended solids and acidity, which contributes to its ecotoxicity. In this work it was intended to study the biodegradation of OMW by microrganisms naturally present in these wastewaters. Thus, an aerobic biological treatment system: a packed-bed batch reactor was applied to a OMW from a mill on northern of Portugal, exploring its autochthon microbial population as inoculum. The biodegradation ability of OMW by microrganisms naturally present in these wastewaters was assessed, by following the evolution of the process and monitoring several of its physico-chemical parameters. Furthermore, an ecotoxicological evaluation, using chronic toxicity tests (Pseudomonas putida growth inhibition test and Vibrio fischeri growth inhibition test), was performed to follow the detoxification capacity of the system as well as its potential to be used in the treatment of this type of agroindustrial effluent

Bioethanol production from agricultural wastes

In this study, different strains of Saccharomyces cerevisiae have been screened for the ability of bioethanol production. Yeasts were grown in synthetic liquid medium containing two different substrates: sucrose at different concentrations (10 to 400g/l) and cane molasses (120g/l of sucrose). The screening was made in batch regime and the growth rates, ethanol and biomass productions were determined. The results indicate a flocculent yeast strain – F as the more suitable microorganism to produce ethanol, presenting the highest value of growth rate (0.49h-1) and ethanol yield (0.40g/g) with 120g/l of sucrose concentration. In addition, ethanol production was also studied in a continuous process with the selected yeast strain (F strain), with sucrose and cane molasses (120g/l) at different dilution rates (0.05-0.5 h-1). Data showed that when dilution rate raised to 0.4h-1 the highest sugar conversion, 85% and 90%, were achieved with an ethanol production of 40.5g/l and 50.8g/l for sucrose and molasses, respectively

Detoxification of olive mill wastewaters using a packed-bed batch reactor

Olive oil production is a traditional agricultural industry in Mediterranean countries and Portugal is one of the ten major producers. This industry generates an effluent, olive mill wastewater (OMW), which does not undergo any treatment and, usually, is stored in evaporation lagoons or spread on the land. Disposal of olive oil mill wastewaters is a serious environmental problem due to its high organic loading, presence of polyphenols and tannins, high content in suspended solids and acidity, which contributes to its ecotoxicity. In this work, a biological treatment system: a packed-bed batch reactor was applied to a Portuguese OMW using its autochthon microbial population as inoculum. Thus, the biodegradation potential of OMW’ microrganisms naturally present in these wastewaters was assessed monitoring several physico-chemical parameters along the process. Ecotoxicity tests (Pseudomonas putida growth inhibition test and Vibrio fisheri growth inhibition test) were carried out to follow the detoxification capacity of the system as well as its potential to be used in the treatment of this type of agroindustrial effluent. In this aerobic treatment, an active microbial community with high degradation ability for the OMW organic load was detected, accounting for 80%, 71% and 61% removal of COD, TSS and phenols, respectively. In addition, a significant decrease in the chronic toxicity of the treated OMW to both bacteria, V. fisheri (62.8%) and P. putida (64.3%), was also observed after 140 days of treatment, highlighting the detoxification potential of the system studie

Treatment and reutilization of effluents: one Mediterranean project

The problematic of effluent treatment from olive oil industry as been the subject of an European Commission funded project (INCO-MED programme): “Mediterranean Usage of Biotechnological Treated effluent Water”. The potential that effluent offers to increase the availability of water, in mediterranean regions, was the final goal of the project, co-ordinated by INETI with partners from EU and MPC. In the project different systems for the treatment of this effluent had been studied: reactors systems (Intensive type) based on the jet-loop principle (JACTO) and an anaerobic UASB hybrid type reactor technology; lagoons (extensive type) for municipal wastewater treatment were also applied. The aerobic JACTO system demonstrated high unit capacity for biological conversion and operation at different loadings, allowing the removal of the pollutant organic load and the toxicity associated with this effluent. The use of this type of reactor for pre-treatment of OOWW prior to disposal on a lagoon system was tested at FSS (Morocco). Use of fungi as a pre-treatment was tested by UNITUS (Italy), EBC (Turkey) and CBS (Tunisia). In this way the effluent could be “improved” as demonstrated in the case of anaerobic digestion and biogas production (CBS). Effluent improvement and enrichment with phosphate was also tested by UNITUS. Analytical monitoring methodologies were developed at IA (Spain) and treated effluents were tested for a number of agricultural applications in different countries. The different alternatives studied will be analysed and compared taking account of technological and socio-economical criteria in relation with the project objectives