Utilization of biogas spent slurry and agricultural waste for eco-friendly biodegradable nursery pots

Abstract

The growing environmental burden of high-density polyethylene (HDPE) nursery bags and the disposal challenge of biogas spent slurry from Compressed Biogas (CBG) plants necessitate sustainable alternatives. This study explores the development of biodegradable nursery pots by valorizing biogas-digested slurry, including pressmud, municipal solid waste, and cow dung slurry, in combination with natural binders such as soil, lime, starch, and guar gum. A hydraulically operated compression molding machine was used to form the pots, which were evaluated for their physical, mechanical, and environmental properties. Results showed that pots formed with biogas slurry and guar gum exhibited superior performance, with compressive strength of 2.34 MPa, moisture content below 1%, shattering resistance of 86% and water absorption resistance under 30%. Biodegradability trials revealed over 90% mass loss within 50-56 days under soil incubation. Germination tests confirmed that these pots support healthy root development, achieving a 100% seed germination rate, surpassing that of HDPE controls. Electrical conductivity of pot leachate remained within safe limits, indicating no phytotoxic effects. The study demonstrates the feasibility of converting CBG slurry and agro-waste into structurally sound, biodegradable nursery pots, presenting a viable, eco-friendly substitute for plastic containers. The findings support sustainable nursery management, circular waste utilization, and align with national organic waste valorization initiatives.