Pietro Carlozzi

Biomass production and studies on Rhodopseudomonas palustris grown in an outdoor, temperature controlled, underwater tubular photobioreactor

A temperature controlled underwater tubular photobioreactor was studied for 6 months in outdoor conditions to determine biomass production of Rhodopseudomonas palustris 42OL. Biomass output rate was very high during the study period. In July, productivity was about 75.0 g reactor(-1) d(-1) for a short period (5 days). The biomass yield averaged 0.7 g biomass dry weight (d.w.)xg acetic acid(-1). We also obtained a mean photosynthetic efficiency of 7.6% in winter and 7.1% in summer. Biomasses rich in pigments and a biodegradable thermoplastic polymer [poly-beta-hydroxybutyrate (PHB)] were obtained. During the summer, PHB was about 4.0% of the biomass d.w. The bacteriochlorophyll/carotenoid ratio was lower at midday than either in the morning or in the evening. The reduction in this ratio may have been a response of the Rhodopseudomonas cells to high irradiance (about 900 W m(-2)). A reduced rate of protein synthesis continued even in the dark. PHB and carbohydrates, synthesized in excess during the day, were used as substrates for night protein synthesis.

The recovery of polyphenols from olive mill waste using two adsorbing vegetable matrices

Olive mill wastewater (OMW) is considered one of the most pollutive waste materials in the Mediterranean basin. However, its phenolic fraction should be recovered, since it has been shown to have incredible benefits for health. In the present study, the adsorbent and desorbent capacities of Azolla and granular activated carbon (GAC) were investigated. The GAC was found to be more efficient than Azolla in both the adsorption and the desorption of phenols. The total characterization of two powder products obtained from Azolla and GAC desorption is reported, together with their antioxidant and antiradical activities. In the Azolla powder product, total polyphenols were more than twice as numerous as those found in the GAC powder product. The GAC powder contained hydroxytyrosol in concentrations that were 3.5 times higher than those of Azolla. On the other hand, both powder products showed great antiradical activities: the IC₅₀ was found to be 102 mg ml⁻¹ for the Azolla and 199 mg ml⁻¹ for the GAC powders respectively. The oxygen radical absorbance capacity was very high: 4097 μmol TE g⁻¹ Azolla powder product and 1277 μmol TE g⁻¹ of GAC powder products.

Productivity of Spirulina in a strongly curved outdoor tubular photobioreactor

The effect of different flow rates (from 0.18 m/s to 0.97 m/s) on the productivity of Spirulina grown outdoors in a strongly curved tubular photo-bioreactor (CTP) was studied. The results were compared to those obtained with a conventional photobioreactor made with straight tubes to form a loop (STP). The cultures were operated at a biomass concentration of 10 g/l dry weight. The productivity of the culture increased by about 39% and 29% in the CTP and STP respectively when the flow rate of the culture was increased from 0.18 m/s to 0.75 m/s. A further increase of the flow rate did not result in any increase of the productivity in either of the photo-bioreactors. The better performance of the culture observed in the CTP was attributed to an intermittent illumination pattern resulting from a secondary flow motion generated in the bends. The power required for the induction of the same flow rate inside the two types of photobioreactor changed significantly. At a Reynolds number of 4000, the power absorbed by the CTP was 25% higher than that required for water recycling in the STP and rose by more than 40% at a Reynolds number of 20000.

Hydrodynamic aspects and Arthrospira growth in two outdoor tubular undulating row photobioreactors.

Abstract Two tubular undulating row photobioreactors (TURPs) with a very high illuminated surface/volume ratio (400 m−1) were designed and constructed for the growth of photosynthetic micro-organisms. Experiments were conducted under outdoor conditions; and Arthrospira recycling was performed with airlifts (one for each row). The rows in each reactor faced east-west and consisted of a flexible polyvinyl chloride pipe (22 m long, 0.01 m bore) arranged in a sinusoidal shape. We studied the hydraulic performance of the sine-shaped photobioreactor rows during culture recycling in the TURPs at a very high Reynolds number (4200), when Arthrospira showed Newtonian fluid behavior. The sinusoidal pipe arrangement imposed a sine waveform on the culture, which led to better light utilization. During summer, a volumetric productivity of 2.2 g l−1 day−1 was reached in the TURP-5r (5 rows m−2), whereas an area productivity of 35 g m−2 day−1 was obtained in the TURP-10r (10 rows m−2). This was due to more light being available in the TURP-5r, because its rows were more spaced out and the photic ratio (Rf) was low (3.0). In the TURP-10r, the closer rows caused a dilution of the sunlight, but gave a better light distribution inside the Arthrospira culture and improved the light utilization. This was attributed to the high Rf (6.0) of this reactor.

Dephenolization of stored olive-mill wastewater, using four different adsorbing matrices to attain a low-cost feedstock for hydrogen photo-production.

This investigation deals with the conversion of olive-mill wastewater (OMW) into several feedstocks suitable for hydrogen photo-production. The goal was reached by means of two sequential steps: (i) a pre-treatment process of stored-OMW for the removal of polyphenols, which made it possible to obtain several effluents, and (ii) a photo-fermentative process for hydrogen production by means of Rhodopseudomonas palustris sp. Four different adsorbent matrices (Azolla, granular active carbon, resin, and zeolite) were used to dephenolize stored-OMW. The four liquid fractions attained by using the above process created the same number of effluents, and these were diluted with water and then used for hydrogen photo-production. The maximum hydrogen production rate (14.31 mL/L/h) was attained with the photo-fermenter containing 25% of the effluent, which came from the pre-treatment of stored-OMW using granular active carbon. Using the carbon effluent as feedstock, the greatest light conversion efficiency of 2.29% was achieved.

Production of bio-fuels (hydrogen and lipids) through a photofermentation process.

The purple non-sulfur photosynthetic bacteria Rhodopseudomonas palustris (strain 42OL) was investigated for a co-production of both bio-H(2) and biodiesel (lipids). The investigation was carried out using malic and glutamic acids in a fed-batch cultivation system under continuous irradiances of 36, 56, 75, 151, 320, 500, and 803 W m(-2). Boltzmanns sigmoidal regression model was used to determine growth kinetic parameters during hydrogen photoevolution. The upper limit of volumetric hydrogen photoevolution was 15.5 + or - 0.9 ml l(-1) h(-1). During the entire cultivation period (408 h), the highest average hydrogen production rate (HPR(av)) of 11.1 + or - 3.1 ml l(-1) h(-1) was achieved at an irradiance of 320 W m(-2). Biomasses stored at the end of each experimental set were analyzed in order to determine lipid content, which ranged from a minimum of 22 + or - 1% to a maximum of 39 + or - 2% of biomass dry weight.

Fatty acid composition of Antarctic cyanobacteria

Pushparaj B., Buccioni A., Paperi R., Piccardi R., Ena A., Carlozzi P., and Sili C. 2008. Fatty acid composition of Antarctic cyanobacteria. Phycologia 47: 430–435. DOI: 10.2216/07-90.1 The 31 Antarctic cyanobacterial strains, object of this study, were isolated from south polar lake sediments, soil and lichen associations and belong to the genera of Cyanothece, Chondrocystis, Leptolyngbya, Pseudophormidium, Phormidium, Hormoscilla and Nostoc. They are maintained in the Culture Collection of the Istituto per lo Studio degli Ecosistemi (ISE-CNR, Florence). The fatty acid composition varied among the strains, with relatively high quantities of polyunsaturated fatty acids. Arachidonic acid was found in two strains of Phormidium pseudopristleyi at 24% and 32% of the total fatty acid content. The total lipid content and the C/N ratio varied among strains from 13% to 9% and 3.7 to 11.2, respectively. The diversity of saturated and unsaturated fatty acid composition among the Antarctic strains and their possible application as nutrient supplements are discussed.

Hydrodynamic alterations during cyanobacteria (Arthrospira platensis) growth from low to high biomass concentration inside tubular photobioreactors.

The rheological behavior of an Arthrospira culture was studied from low to high biomass concentration. Two tubular undulating row photobioreactors (TURP‐5r and TURP‐10r), with a very short light path of 1.0 cm, were used during batch growth. In TURP‐5r, the biomass concentration increased to 14.5 g(dw) L−1, and alterations of the physical properties and hydrodynamic behavior occurred as a result. In the past, the rheological characteristics of photosynthetic‐microbe cultures were rarely investigated because of the low biomass concentration attained in the systems. Developing closed photobioreactor technologies, the optimum biomass concentration rises and the viscosity, the generalized Reynolds number (N′Re), and the power required for culture recycling are also subject to alteration. Starting from a biomass concentration of 4.1 g(dw) L−1, the Arthrospira culture already exhibits the characteristics of a non‐Newtonian fluid. As a result of culture recycling from 2.0 to 20.5 g(dw) L−1 and an available power of 1.67 W row−1, we demonstrated that N′Re is reduced from 6265 to 1148. Our experimental results showed that N′Re of 2345 can be reached only at a cell concentration below 11.1 g(dw) L−1, while at a cell concentration below 4.1 g(dw) L−1 N′Re = 4080 was reached. The power consumption (Pc) for culture recycling increased noticeably when the cell concentration rose; the highest Pc increase attained was from 2.0 to 4.1 g(dw) L−1. This is the range within which the Arthrospira culture changes from a Newtonian to a non‐Newtonian fluid.