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EPS production by bacteria from high salinity wastewater.

Publication . Paulo, Ana M.S.; Amorim, Catarina L.; Castro, Paula M.L.

Aerobic granular sludge (AGS) is a promising technology for treating industrial wastewater, possessing higher biomass retention and tolerance to toxic substrates than conventional activated sludge systems. The presence of extracellular polymeric substances (EPS) in the aerobic granules structure increases the bacterial protection towards stress conditions and the stability of granules. Several industrial wastewaters contain high salt concentrations in their composition, which can inhibit the bacteria responsible for nutrients removal in the AGS process [1]. A novel strategy to increase the robustness of the system to high salinity is to bioaugment the aerobic granules with halotolerant bacteria with ability to produce EPS. Using a robust AGS process, extra value can be obtained from the wastewater since the EPS from the biomass can be recovered and used as new biomaterials in different applications. The aim of the present study is to investigate the feasibility of EPS production by halotolerant bacteria isolated from high salinity wastewater collected in a fish canning industry. Bacterial isolates obtained from the saline water were grouped according to species similarity, based on RAPD profiles. Isolates displaying unique RAPD profiles were subsequently identified by 16S rRNA gene sequencing analysis. The potential for EPS production by isolates presenting a sticky growth on agar plates is currently being evaluated. The content in proteins, humic acids and carbohydrates of the extracted EPS is quantified using reference methods. The obtained isolates are closely related to bacterial strains from the Acinetobacter, Psychrobacter, Arthrobacter, Bacillus, Exiguobacterium and Kocuria genera. The isolated halotolerant bacteria present different ability to produce EPS. The most promising EPS producers will be used for bioaugmentation of an AGS process treating high salinity wastewater. Valorization of the wastewater through EPS recovery from the AGS is in line with the circular economy concept.

2017-12-07Conference object

Open access

Screening of bacteria and microalgae for bioremediation of florfenicol in aquaculture water streams

Publication . Amorim, Catarina L.; Couto, Ana T.; Castro, Paula M.L.

The occurrence of antibacterial agents in natural environment had recently received growing concern due to potential adverse effects on human health and aquatic ecosystems. Florfenicol (FF) is a synthetic phenicol antibiotic, widely used in veterinary medicine for treating diverse infections, and inevitably released into the environment, either from uneaten medicated pelleted feed or through urinary, branchial, and fecal excretion. This is one of the few approved antibiotics for use in aquaculture during both production and processing operations, mainly to prevent and treat bacterial diseases. Up to now, removal of FF has been mainly reported using physical-chemical processes but its removal by biological processes is scarce. Considering that many species of bacteria and microalgae can grow in a wide variety of wastewaters and industrial effluents and have been proven to be efficient in removing nitrogen, phosphorus and other pollutants, there is a niche opportunity to use those microorganisms in bioremediation processes. In this study, the potential of bacteria and microalgae, some isolated from a fish farm, to deal with FF was evaluated. Biodegradation of FF was assessed in batch mode in the presence of a conventional carbon source. Labrys portucalensis F11 could degrade ca. 36% of FF, initially supplied at 12 µM, releasing about 24% of fluoride ion. Several microalgae strains were isolated from sludge and water collected in a fish farm using different nutrient media Screening of microalgae able to cope with FF toxicity is under evaluation using a disc-diffusion type bioassay. Microorganisms able to deal with FF are suitable for application in bioremediation processes towards more efficient biological removal processes.

2018-09-09Conference object

Open access

Simultaneous partial nitrification and 2-fluorophenol biodegradation with aerobic granular biomass: reactor performance and microbial communities

Publication . Ramos, Carlos; Amorim, Catarina L.; Mesquita, Daniela P.; Ferreira, Eugénio C.; Carrera, Julián; Castro, Paula M. L.

An aerobic granular bioreactor was operated for over 4months, treating a synthetic wastewater with a high ammonium content (100mgNL-1). The inoculum was collected from a bioreactor performing simultaneous partial nitrification and aromatic compounds biodegradation. From day-56 onwards, 2-fluorophenol (2-FP) (12.4mgL-1) was added to the feeding wastewater and the system was bioaugmented with a 2-FP degrading bacteria (Rhodococcus sp. FP1). By the end of operation, complete 2-FP biodegradation and partial nitrification were simultaneously achieved. Aerobic granules remained stable over time. During the 2-FP loading, a shift in the community structure occurred, coinciding with the improvement of 2-FP degradation. DGGE analysis did not allow to infer on the bioaugmented strain presence but pyrosequencing analysis detected Rhodococcus genus by the end of operation. Together with other potential phenolic-degraders within granules, these microorganisms were probably responsible for 2-FP degradation.

2017Journal article

Restricted access

Aerobic granular sludge: treatment of wastewaters containing toxic compounds

Publication . Amorim, Catarina L.; Moreira, Irina S.; Duque, Anouk F.; Loosdrecht, Mark C. M. van; Castro, P. M. L.

Aerobic Granular Sludge (AGS) has been successfully applied for carbon, nitrogen and phosphorous removal from wastewaters, in a single tank, reducing the space and energy requirements. This is especially beneficial for, often space restricted, industrial facilities. Moreover, AGS holds a promise for the toxic pollutants removal, due to its layered and compact structure and the bacteria embedding in a protective extracellular polymeric matrix. These outstanding features contribute to AGS tolerance to toxicity and stability. Strategies available to deal with toxic compounds, namely granulation with effluents containing toxics and bioaugmentation, are addressed here. Different applications for the toxics/micropollutants removal through biosorption and/or biodegradation are presented, illustrating the technology versatility. The anthropogenic substances effects on system performance and bacterial populations established within AGS are also addressed. Combination of contaminants removal to allow water discharge, and simultaneous valuable products recovery are presented as final remark.

2017Book part

Restricted access

Wastewater valorization by pure bacterial cultures to Extracellular Polymeric Substances (EPS) with high emulsifying potential and flocculation activities

Publication . Drakou, Efi‑Maria; Amorim, Catarina L.; Castro, Paula M. L.; Panagiotou, Fostira; Vyrides, Ioannis

Nowadays much effort has been devoted for the development of cost-effective and environmentally friendly processes to obtain extracellular polymeric substances (EPS) with high emulsifying and flocculation activities. The aim of this study was to evaluate the capacity of bacterial strains previously isolated from oil-contaminated areas to produce EPS with high emulsification and bioflocculant properties during cultivation in domestic and bilge wastewater and in industrial crude glycerol. A total of seven bacterial strains were screened for EPS production, from which two strains, Pseudomonas aeruginosa LVD-10 and Enterobacter sp. SW, were selected as potential EPS producers. EPS with high emulsifying capacity in olive oil (a maximum of 96.6 and 89.8% for strain SW and LVD-10, respectively) was produced using bilge wastewater as substrate. EPS with a slightly lower emulsifying capacity was obtained using crude glycerol. In addition, the flocculation activity of the EPS extracted from strains LVD-10 and SW grown on crude glycerol was considerably higher (81.6 and 73.3%, respectively) than that obtained with other substrates. This is the first study that points out that EPS with emulsifying and flocculation potential activity can be produced from bilge wastewater and crude glycerol. The production of biopolymers with broad biotechnological applications using low-cost substrates can be a means to valorise waste streams.

2018Journal article

Open access