Sugar Beet Processing Wastewater Treatment by Microalgae through Biosorption

Nadiia Khakimova,Nikola Maravić,Aleksandra Mišan,Petar Davidović,Anamarija Mandić,Zita Šereš,Vesna Pešić,Milena Bečelić-Tomin,Jelica Simeunović,Dajana Blagojević,Milica Pojić

doi:10.3390/w14060860

Abstract

The aim of this study was to investigate the potential of environmental pollution reduction of sugar beet processing factory wastewater by the biorefinery approach and integration of microalgae biomass production. In the present study, Chlorella vulgaris was cultivated in wastewater collected from a sugar beet processing factory at the beginning and at the end of a sugar plant campaign in an aerobic bioreactor on a laboratory scale under controlled conditions, with an air flow of 0.4 L/min, a temperature of 26 °C, and pH = 8. Microalgae showed effective nutrient remediation from wastewater. During wastewater treatment, chemical oxygen demand (COD) and biological oxygen demand (BOD) removal efficiency was 93.7% and 98.1%, respectively; total organic carbon (TOC) content decreased by 95.7%. Nitrites and nitrates decreased by 96%, while the biggest decrease in metal ions was achieved for Ca and Mn (82.7% and 97.6%, respectively). The findings of this study suggest that coupling microalgae cultivation and wastewater treatment has a lot of potential for reducing contamination through biosorption, while also providing environmental advantages.

Highlights

The sugar industry, with global production of sugar exceeding 18 million tons annually, is one of the most important agro-based industries, in which sugar beet accounts for more than 20% of global sugar production [1].As the European Union set the goal to reach carbon neutrality by 2050, the sugar industry has decreased its CO2 emissions by 51% compared to 1990, but achieving climate neutrality still presents a real challenge for this sector
Chemical oxygen demand (COD) and biological oxygen demand (BOD) removal efficiency was 93.7% and 98.1%, respectively; total organic carbon (TOC) content decreased by 95.7%
The obtained results of using mixotrophic species of C. vulgaris showed that this alga is effective in reducing chemical oxygen demand (COD), BOD, TOC, nitrogen, and certain metal ions from sugar beet wastewater

Summary

Introduction

The sugar industry, with global production of sugar exceeding 18 million tons annually, is one of the most important agro-based industries, in which sugar beet accounts for more than 20% of global sugar production [1].As the European Union set the goal to reach carbon neutrality by 2050, the sugar industry has decreased its CO2 emissions by 51% compared to 1990, but achieving climate neutrality still presents a real challenge for this sector. The generation of enormous amounts of pulp, the consumption of large quantities of lime (which are transformed into sludges), the production of vinasse, and high consumption of energy and water are the main sources of sustainability challenges and environmental management problems in traditional beet sugar processing [2]. The sugar beet industry is one of the top water users and wastewater producers, water consumption depends on technological processes within the plant [3]. 25–45 kg water per 100 kg beet and discharges of an even larger quantity of wastewater (including water contained in the beet processed) are still considered normal [4]. Processing wastewaters, if not properly managed, are a serious risk to human beings, the environment, and the recipient’s aquatic life, as they contain a high concentration of organic compounds, especially soluble and insoluble polysaccharides, which presents an ideal environment for the proliferation of microbes [4]

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