Effects of Biochar and Clinoptilolite on Composition and Gaseous Emissions during the Storage of Separated Liquid Fraction of Pig Slurry

José L S Pereira,Vitor Figueiredo,Maria E F Silva,Dulcineia F Wessel,António F M A Pinto,Isabel Brás,Adelaide Perdigão

doi:10.3390/app10165652

Abstract

The storage of animal manure is a major source of gaseous emissions. The aim of this study was to evaluate the effects of biochar and clinoptilolite on the composition and gaseous emissions during the storage of separated liquid fraction of pig slurry. The experiment was carried out using containers with 6 L of pig slurry each. The additives biochar and clinoptilolite were added alone and mixed to the pig slurry at a rate of 2.5% each, in a total of four treatments with three replicates including the control. Gaseous emissions were monitored by a photoacoustic multigas monitor, and slurry samples were collected at 0 and 85 days and their composition assessed. Results showed that the addition of biochar could modify the physicochemical properties of the slurry. The addition of biochar did not reduce the E. coli during the experiment while clinoptilolite decreased its prevalence. The addition of biochar or clinoptilolite reduced significantly the NH3 emission during the storage of slurry, but no advantages were gained with their combination. The addition of biochar significantly reduced the CO2 and CH4 emissions relative to clinoptilolite, however N2O emissions and global warming potential did not differ among the additives. We conclude that the biochar and clinoptilolite are recommended as a mitigation measure to reduce gaseous emissions and preserve the fertiliser value at slurry storage.

Highlights

The strong increase in intensive livestock production has led to severe environmental problems due, essentially, to the management of the large amounts of slurry resulting from this activity
In order to follow the changes in slurry composition and gaseous emissions after application of additives at the storage of pig slurry, a laboratory experiment was conducted in which the slurry was amended with biochar and/or clinoptilolite
The results indicated that the addition of biochar could modify the physicochemical properties of the liquid fraction

Summary

Introduction

The strong increase in intensive livestock production has led to severe environmental problems due, essentially, to the management of the large amounts of slurry (liquid manure) resulting from this activity. The storage of animal manure is a major source of ammonia (NH3 ), nitrous oxide (N2 O), carbon dioxide (CO2 ) and methane (CH4 ) emissions, all with important impacts on climate change, acid rain and ozone formation in the troposphere [1,2,3]. Sci. 2020, 10, 5652 animal manure management, namely: 10% for feeding, 20% for housing, 40% for storage and 30% for soil application. The NH3 and CO2 are originated by decomposition of urea present in slurry and the main characteristics that control NH3 volatilisation are temperature, concentration of total ammoniacal N, pH and air velocity on slurry surface [4,5]. Nitrification can be performed by autotrophic and heterotrophic organisms under aerobic conditions whereas denitrification is the stepwise reduction of nitrate (NO3 − )

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