The Quantity and Composition of Leachate from Hop Plant Biomass during Composting Process

Barbara Čeh,Aleš Hladnik,Julija Polanšek,Boštjan Naglič,Lucija Luskar,Žan Trošt

doi:10.3390/app12052375

Barbara Čeh, Aleš Hladnik + Show 4 more

Open Access

https://doi.org/10.3390/app12052375

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Abstract

Technology that would result in a high-quality product with minimal environmental impact throughout the on-site composting process of hop biomass after harvest has not yet been developed. It is crucial to introduce composting practices that do not result in a detrimental leachate impact. Three different composting procedures that vary in terms of initial biomass particle size, additives, and pile covering were investigated. Each pile was built from 15 t of fresh hop biomass after harvest (leaves and stems), leachate was collected during the composting season (September to the end of April), and biomass was sampled and analyzed to identify good practices as well as gaps that need to be filled. Leachate quantity differed significantly in terms of the composting procedure and time stamps. There was a strong linear correlation between the amount of precipitation and leachate quantity (0.86), NH4 leached amount (0.87), and total N leached amount (0.92), but not the total P amount. The composting procedure had a significant impact on the quantity of the NH4 leached amount. The majority of the NH4 was lost in the second month of composting. The maturation phase was the most critical for NO3 loss since it had the highest amount of leached NO3 and the greatest variances among the composting protocols. Considering leachate it is recommended that a membrane is used at all times during the maturation phase as well as during any heavy precipitation expected in the thermophilic phase. Whether the cover is also needed for the entire duration of the thermophilic phase (due to emission) is a matter of further research.

Highlights

During harvest, hop plants are cut down and the whole aboveground biomass is removed from the fields
The technology that would result in a high-quality product with a minimal environmental impact during the composting process is still in its infancy and needs to be developed
The leachate was a sum of leachate from the composting process and rain that fell on the pile throughout the composting pile

Summary

Introduction

Hop plants are cut down and the whole aboveground biomass is removed from the fields. While cones are picked, dried, and packed for the brewing industry, stems and leaves (hop biomass after harvest) constitute a by-product [1]. Due to the presence of polypropylene twine, which is commonly used as support for hop plants, this biomass has not been recycled on farms. The introduction of biodegradable twine has made on-site composting a highly essential practice [3]. The technology that would result in a high-quality product with a minimal environmental impact during the composting process is still in its infancy and needs to be developed

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