Winery Wastewater Treatment by Microalgae to Produce Low-Cost Biomass for Energy Production Purposes

Elena Spennati,Alessandro Alberto Casazza,Attilio Converti

doi:10.3390/en13102490

Abstract

Even though biofuel production from microalgae has become more and more attractive in recent years, it is limited especially by the high cost of microalgae cultivation. However, microalgae can be grown in wastewater in order to reduce their production cost and, at the same time, the polluting impact of wastewaters. Winery wastewaters, which are abundantly released from the wine making process, have a large pollution impact related to their high loads of total solids, chemical oxygen demand (COD) and polyphenol concentration. In this research work a co-culture of Chlorella vulgaris and Arthrospira platensis was used to treat three different winery wastewaters from different steps of the wine production process, in order to produce low-cost biomass intended for biofuel production. Growth of the co-culture and reduction of wastewater pollutant impact were followed by daily determinations of biomass concentration, COD and polyphenol content. The highest productivities of biomass (0.66 gDry Weight/L·day) and lipids (7.10 ± 0.22 gLipid/100 L·day) were obtained using 20% of second washing winery wastewater after 4 days of treatment. Moreover, COD and polyphenol content of the three different wastewaters were reduced by the co-culture by more than 92% and 50%, respectively. These results suggest that winery wastewaters can be used successfully for the growth of A. platensis and C. vulgaris co-culture in order to obtain inexpensive biomass for energy production purposes.

Highlights

The reduction of fossil fuels reserves and the continuously increasing demand for energy around the world has led to the necessity to find an eco-sustainable alternative to conventional fuels
Pinto et al [31], who investigated the removal of different phenolic compounds by Scenedesmus obliquus, A Chlorella vulgaris and Arthrospira platensis co-culture was grown in three different winery wastewaters (WWWs), namely those from the first (W1) and second (W2) tank washings as well as that from the filtration equipment (W3)
The same inverse correlation between polyphenol concentration and removal was observed by Papazi et al [32] for olive mill wastewater treatment by the same microalga, in that tyrosol removal decreased from 75% to 15% when its concentration was increased from 0.05 to 0.3 mM

Summary

Introduction

The reduction of fossil fuels reserves and the continuously increasing demand for energy around the world has led to the necessity to find an eco-sustainable alternative to conventional fuels. Third-generation biofuels can be produced from microalgal biomasses or from their intracellular components such as lipids Their production, if compared to conventional biomasses, reduces land and water utilization along with the use of pesticides [2]. Microalgae are unicellular microorganisms able to grow under autotrophic, heterotrophic or mixotrophic conditions depending on the carbon source used in their metabolism as well as light conditions [3]. They are composed mainly of lipids, proteins and carbohydrates, whose relative proportions depend in particular on the species and growth conditions [4]. They are generally used for human or animal nutrition [5], or extraction of added-values components for chemical and pharmaceutical industries [6], and for biofuel production [7]

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