Nitrogen and Phosphorus Recovery From Anaerobically Pretreated Agro-Food Wastes: A Review

José Luis Campos,Óscar Franchi,Marisol Belmonte,Ángeles Val Del Río,Alba Pedrouso,Anuska Mosquera-Corral,Dafne Crutchik,Juan Pablo Pavissich

doi:10.3389/fsufs.2018.00091

Abstract

Anaerobic digestion (AD) is commonly used for the stabilization of agro-food wastes and recovery of energy as methane. Since AD removes organic matter but not nutrients (N and P), additional processes to remove them are usually applied to meet the stringent effluent criteria. However, in the past years, there was a shift from the removal to the recovery of nutrients as a result of increasing concerns regarding limited natural resources and the importance given to the sustainable treatment technologies. Recovering N and P from anaerobically pretreated agro-food wastes as easily transportable and marketable products has gained increasing importance to meet both regulatory requirements and increase revenue. For this reason, this review paper gives a critical comparison of the available and emerging technologies for N and P recovery from AD residues.

Highlights

Anaerobic digestion is the most widely applied technology for the treatment of agro-food industry waste, given its proven operational reliability and the obtaining of methane as a source of renewable energy, which generally allows amortizing the initial investment costs (Ren et al, 2017)
During anaerobic digestion hydrolysis takes place and organic matter, ammonia, phosphate, potassium, magnesium, calcium, and sulfur are released to the bulk liquid
Nitrogen and Phosphorus Recovery if the social and environmental benefits of P recovery are quantified, the economic balance turns in favor of P recovery (Molinos-Senante et al, 2011; Mayer et al, 2016; Corbala-Robles et al, 2018)

Summary

Introduction

Anaerobic digestion is the most widely applied technology for the treatment of agro-food industry waste, given its proven operational reliability and the obtaining of methane as a source of renewable energy, which generally allows amortizing the initial investment costs (Ren et al, 2017). N can be considered as a renewable resource but its conversion into fertilizer by means of the Haber-Bosch process requires a high amount of energy, with its cost dependent on the price and supply of natural gas (Zarebska et al, 2015).

Results

Conclusion