Concept Bioconversion of olive mill wastewater (OMW) in bioplastics as polyhydroxyalcanoate (PHA). This investigation deals with the conversion of dephenolized OMW into a feedstock suitable for PHA photo-production by means of cyanobacteria. 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 an effluent, and (ii) a process carried out by means of a few cyanobacteria for the PHA production. A granular active carbon (GAC) was used to dephenolize stored-OMW to obtain an effluent (low-cost feedstock) suitable for growing photosynthetic microorganisms [1]. Several cyanobacteria have the capacity to accumulate PHA in dry-biomass during the growth. A selected PHA accumulating strain was grown in a culture broth containing different amounts of GAC effluent using an indoor flat-glass photobioreactor (Fig. 1). Experiments were performed at a constant temperature under continuous light. The consumption of the volatile acid content and the organic load (expressed as chemical oxygen demand - COD) in the culture was followed during cyanobacteria growth. Motivations and Objectives Olive-mill wastewater is a type of waste that is characterized by a considerable organic load (40-220 g/L) [2]. The high content of phenolic compounds is what gives OMW its black-brownish colour, which depends on the ratio between the two groups of polyphenols as low-MW and high-MW [3]. One of the powerful treatment processes for removing colour inexpensively from water is adsorption (4). Polyphenol removal from stored-OMW has been recently investigated [1]. The main goal of the present investigation was the production of rich-PHA dry-biomass using GAC-effluent from stored-OMW. Results and Discussion Some potential cyanobacteria have been selected as potential candidates for the production of PHA using culture broth containing diluted GAC effluents. During this preliminary study, a cyanobacterium was grown in a culture broth containing different amounts of GAC effluent using a flat-glass photobioreactor. Figure 2a shows the mixotrophic growth apparatus used for growing the cyanobacterium in the culture broth containing GAC-effluent. The consumption of both volatile acids and COD is shown in the Figure 2b. The culture broth containing higher amount of GAC-effluent was not suitable for mixotrophic growth. The unsuitable growth of selected cyanobacterium strain observed in the medium containing high GAC-effluent was attributed to the faster growth of bacteria than cyanobacterium, which led to a progressive anoxic conditions into the culture. Studies about PHA accumulation in dry-biomass of cyanobacterium grown under autotrophic, and mixotrophic nutrition mode are in progress.
Cyanobacteria growth in culture broth containing olive mill wastewater using a flat-glass photobioreactor for the production of rich-PHA biomasses
P Carlozzi;G Padovani;
2013
Abstract
Concept Bioconversion of olive mill wastewater (OMW) in bioplastics as polyhydroxyalcanoate (PHA). This investigation deals with the conversion of dephenolized OMW into a feedstock suitable for PHA photo-production by means of cyanobacteria. 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 an effluent, and (ii) a process carried out by means of a few cyanobacteria for the PHA production. A granular active carbon (GAC) was used to dephenolize stored-OMW to obtain an effluent (low-cost feedstock) suitable for growing photosynthetic microorganisms [1]. Several cyanobacteria have the capacity to accumulate PHA in dry-biomass during the growth. A selected PHA accumulating strain was grown in a culture broth containing different amounts of GAC effluent using an indoor flat-glass photobioreactor (Fig. 1). Experiments were performed at a constant temperature under continuous light. The consumption of the volatile acid content and the organic load (expressed as chemical oxygen demand - COD) in the culture was followed during cyanobacteria growth. Motivations and Objectives Olive-mill wastewater is a type of waste that is characterized by a considerable organic load (40-220 g/L) [2]. The high content of phenolic compounds is what gives OMW its black-brownish colour, which depends on the ratio between the two groups of polyphenols as low-MW and high-MW [3]. One of the powerful treatment processes for removing colour inexpensively from water is adsorption (4). Polyphenol removal from stored-OMW has been recently investigated [1]. The main goal of the present investigation was the production of rich-PHA dry-biomass using GAC-effluent from stored-OMW. Results and Discussion Some potential cyanobacteria have been selected as potential candidates for the production of PHA using culture broth containing diluted GAC effluents. During this preliminary study, a cyanobacterium was grown in a culture broth containing different amounts of GAC effluent using a flat-glass photobioreactor. Figure 2a shows the mixotrophic growth apparatus used for growing the cyanobacterium in the culture broth containing GAC-effluent. The consumption of both volatile acids and COD is shown in the Figure 2b. The culture broth containing higher amount of GAC-effluent was not suitable for mixotrophic growth. The unsuitable growth of selected cyanobacterium strain observed in the medium containing high GAC-effluent was attributed to the faster growth of bacteria than cyanobacterium, which led to a progressive anoxic conditions into the culture. Studies about PHA accumulation in dry-biomass of cyanobacterium grown under autotrophic, and mixotrophic nutrition mode are in progress.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
