Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: New metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes

Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD-coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation-were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria-Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step

Continuous flow adsorption of phenolic compounds from olive mill wastewater with resin XAD16N: life cycle assessment, cost\u2013benefit analysis and process optimization

BACKGROUND: Olive mill wastewaters (OMWs) represent a major environmental concern due to their high organic load and phytotoxic activity. The selective recovery of phenolic compounds (PCs) from OMW is promising, thanks to the antioxidant and antimicrobial properties of PCs. The goal of this work was to perform a life cycle assessment (LCA) and cost\u2013benefit analysis (CBA) of a full-scale process of PC adsorption/desorption on resin Amberlite XAD16N. The industrial process was designed on the basis of laboratory tests aimed at performing a preliminary process optimization. RESULTS: Adsorption tests were conducted at different velocities in a 1.8-m column packed with XAD16N. The optimal superficial velocity and retention time (2.78 m h \u20131 and 0.56 h) allowed the attainment of satisfactory performances in terms of resin operating capacity (0.46), PC adsorption yield (0.92), PC mass fraction in the sorbed product (0.50 g PC /g VS ) and specific antioxidant activity (3\u20136 g ascorbic acid /g PC ). Six consecutive adsorption/desorption cycles, operated with the same resin load, resulted in stable process performances. The LCA indicated that the environmental impact of the process could be decreased markedly through the addition of an anaerobic digestion step for the production of irrigation-quality water and fertilizers from the dephenolized OMW. The PC market price required for the generation of a positive business case resulted relatively low (\u20ac1.7\u201313.5 kg PC\u20131 ). CONCLUSION: The results indicate that the proposed PC adsorption/desorption technology, if integrated with an anaerobic digestion step, represents a promising solution for the treatment and valorization of OMW, a major agro-industrial waste in Mediterranean countries

Development of a continuous-flow anaerobic co-digestion process of olive mill wastewater and municipal sewage sludge

BACKGROUND: Olive mill wastewater (OMW) represents an environmental problem due to its high organic load and relevant concentration of phenolic compounds (PCs). OMW treatment and disposal represents a relevant challenge and cost for olive mills and multi-utilities in charge of waste management in Mediterranean countries. The goal of this study was to develop an anaerobic co-digestion (co-AD) process of OMW and sewage sludge (SwS) from municipal wastewater treatment. RESULTS: Different volumetric OMW:SwS ratios up to 100% OMW were fed in continuous 1.7-L bioreactors. The reactors fed with raw OMW (rOMW) performed better than those fed with OMW dephenolized by adsorption (dOMW). At a 23-day hydraulic retention time, the best performances were obtained in the reactor fed with 25% rOMW, with a 105% increase in methane yield in comparison to the 100% SwS test. At a 40-day hydraulic retention time, the reactor fed with 40% rOMW attained a 268 NLCH4/kgvolatile solids methane yield. The conversion of phenolic compoundsreached 70% when the hydraulic retention time was increased from 23 to 40 days. A cost\u2013benefit analysis indicated that both rOMW co-AD in existing digesters and phenolic compounds recovery from OMW followed by co-AD of dOMW can lead to relevant additional revenues for the multi-utilities in charge of wastewater management. CONCLUSION: This work proves that, using the existing network of SwS anaerobic digesters, it is feasible to co-digest the entire OMW production in regions characterized by intense olive oil production, thus attaining a relevant increase in methane production yield (a 144% increase in comparison to 100% SwS)

Microorganism and enzyme Immobilization: NOvel Techniques and Approaches for Upgraded Remediation of Underground-, wastewater and Soil

MINOTAURUS will deliver innovative bio-processes (bioaugmentation, enzyme technology, rhizoremediation with halophytes, and bioelectrochemical remediation), which are all based on the concept of IMMOBILIZATION OF BIOCATALYSTS (microorganisms and enzymes), to eliminate emerging and classic organic pollutants. The immobilization-based technologies will be applied to engineered (ex-situ) and natural systems (in situ) for the bioremediation of groundwater, wastewater, and soil. The selection and adaptation of modern physico-chemical, biological, and ecotoxicological monitoring tools combined to a rational understanding of engineering and enzymology/microbial physiology aspects is a pertinent approach to open the black-box of the our technologies. The reliable process-monitoring will constitute a solid basis to develop and refine our biodegradation kinetics models, which will be the mean to improve the predictability of performances to be achieved with our technologies. A key strength of MINOTAURUS is the possibility of direct implementation of our technologies at five EU reference sites that are confronted with pollutants (two technologies will be tested on-site during the first year). We will deliver not only a set of tools, techniques and processes which will enhance the ability of our communities to respond to the challenges of organic pollutants but also frameworks for structuring and making evidence-based decisions for the most sustainable and appropriate bioremediation measures. MINOTAURUS consortium consists of fifteen partners from eight European and Europe-associated countries. Eight research & education institutions, five SMEs covering the whole chain of our bioremediation approaches (production/monitoring of biocatalysts, bioremediation, and engineering), one large end-user installing wastewater treatment plants, and one environmental agency will work together with the support of an advisory board mainly consisting of environmental decision-makers

Numerical parameters estimation in models of pollutant transport with chemical reaction

In this work we present an iterative algorithm for solving a parameter identification problem relative to a system of diffusion, convection and reaction equations. The parameters to estimate are the retardation factors, diffusivity, reaction and transport coefficients relative to a model of pollutant transport with chemical reaction. The proposed method solves the nonlinear least squares problem by means of a sequence of constrained optimization problems. The algorithm does not depend on the type of discretization method used to solve the state equation. The results reported in the numerical tests show the efficiency of the algorithm in terms of performance and solution quality

Investigation of the effect of specific operational parameters on a process of chloroform cometabolic biodegradation by butane-grown biomasses

An aerobic cometabolic CF degradation process by butane-grown biomasses was studied by means of slurry microcosm tests. The lag-phase for the onset of butane utilization by the indigenous biomass of the studied sandy soil was lower than 2 weeks in all the experimental conditions tested. The lag-time for the onset of CF depletion was strongly affected by temperature, with no CF degradation after several weeks in the tests conducted at 15\ub0C. Bioaugmentation treatments performed with 2 types of microbial inocula led, even at the smallest dose tested (0.15 grams of dry cell / m^3 of aq. phase), to a marked decrease of the butane lag-time. Both the initial CF degradation rate and the amount of CF depleted in the absence of butane proved to depend on the type of inoculum utilized, rather than on its dose. The minimum butane/CF molar ratio required to carry out a sustainable CF degradation process proved to be comprised between 1.6 and 14

Biodegradazione aerobica cometabolica di 1,1,2,2-tetracloroetano: prove di bioaugmentation in microcosmi

L\u2019obiettivo di questo lavoro \ue8 stato lo studio del processo di biodegradazione aerobica cometabolica dell\u20191,1,2,2-tetracloroetano (TeCA) ad opera di biomasse metanotrofe e propanotrofe. La sperimentazione \ue8 stata condotta in microcosmi allestiti sia in condizioni slurry che, limitatamente alla biomassa propanotrofa, liquido/gas. I risultati indicano che il TeCA pu\uf2 essere biodegradato tramite cometabolismo aerobico ad opera sia di biomasse metano-utilizzatrici che propano-utilizzatrici nell\u2019intervallo 0-600 mg/l aq., e che tale processo pu\uf2 essere protratto per parecchi mesi senza che si verifichino fenomeni di inattivazione o danneggiamento delle biomasse oggetto di studio. Il trattamento di bioaugmentation ha consentito di ridurre drasticamente il lag-time per l\u2019avvio del processo degradativo cometabolico. I risultati positivi ottenuti nei microcosmi liquido/gas dimostrano che, a partire da pochi ml di biomassa propano-utilizzatrice sviluppata nei microcosmi slurry, \ue8 possibile produrre elevati quantitativi di inoculo tramite un processo di crescita in bioreattori non contenenti terreno, senza che si verifichino significative diminuzioni dell\u2019efficacia dell\u2019inoculo nella degradazione del TeCA