Coupling of Microalgae Cultivation with Anaerobic Digestion of Poultry Wastes: Toward Sustainable Value Added Bioproducts.

Rajinikanth Rajagopal,Seyyed Ebrahim Mousavi,Bernard Goyette,Suman Adhikary

doi:10.3390/bioengineering8050057

Rajinikanth Rajagopal, Seyyed Ebrahim Mousavi + Show 2 more

Open Access

https://doi.org/10.3390/bioengineering8050057

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Abstract

Third generation biofuels and high-value bioproducts produced from microalgal biomass have been considered promising long-term sustainable alternatives for energy and/or food production, potentially decreasing greenhouse gas emissions. Microalgae as a source of biofuels have been widely studied for bioethanol/biodiesel/biogas production. However, critical research is needed in order to increase the efficiency of microalgae production from high-N agri-waste, not only for biofuels but also for bio-based products, and thus enhance its commercial viability. The growth in the poultry industry has led to increased chicken manure (CM), which are rich in ammonia, phosphate, potassium, and other trace elements. These constituents could be used as nutrients for growing microalgae. In this research, a two-stage (liquid–solid) anaerobic digester treating CM at 20 ± 1 °C was performed, and liquid digestate (leachate) obtained after the digestion process was used as a substrate to grow the microalgal strain Chlorella vulgaris CPCC 90. Considering the high-N content (NH3-N: 5314 mg/L; TKN: 6197 mg/L) in liquid digestate, different dilutions were made, using distilled water to obtain viz. 10%, 30%, 50%, 70%, 90%, and 100% of the digestate concentrations for the microalgae cultivation. Preliminary results showed that Chlorella vulgaris CPCC 90 was able to grow and utilize nutrients from a 10% diluted CM digestate. Future research is underway to enhance microalgal growth at higher digestate concentrations and to optimize the use of microalgae/microalgae-bacteria consortia for better adaptation to high-N content wastes. An AD-microalgae coupling scenario has been proposed for the circulation bioeconomy framework.

Highlights

Canada’s commercial chicken and turkey meat production was over 1.43 billion kilograms in 2018 and the demand for poultry meat production as the most consumed meat animal protein source is growing at an average rate of around 2.3% annually [1].In order to process this high volume of manure, appropriate manure management strategies are necessary
The liquid inoculum used in the start-up phase of HS–anaerobic digestion (AD) was obtained from our ongoing laboratory-scale liquid sequencing batch AD, adapted to chicken manure (CM)
high-solid anaerobic-digestion (HS–AD)) AD process, which was adopted as a pre-treatment for microalgae cultivation

Summary

Introduction

Canada’s commercial chicken and turkey meat production was over 1.43 billion kilograms in 2018 and the demand for poultry meat production as the most consumed meat animal protein source is growing at an average rate of around 2.3% annually [1].In order to process this high volume of manure, appropriate manure management strategies are necessary. The treatment of poultry wastes has gained attention for its environmental impact mainly due to its high organic and high nutrients, including nitrogen (N) and phosphorus (P) loads. A broad range of CM treatment technologies have been reported, such as anaerobic digestion, direct combustion, extruding, and rendering [3,4,5,6]. Among these technologies, anaerobic digestion (AD) can play an important role in the management of CM, as, unlike other techniques, it is comparatively a low-cost process for livestock farming and relatively easy to apply in farms [3].

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