Turning livestock waste into clean water: Animal manure biochar emerges as a low cost tool to remove toxic pollutants from wastewater
Biochar Editorial Office, Shenyang Agricultural University
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Animal manure biochar for the removal of hazardous pollutants from wastewater
view moreCredit: Sangyoon Lee, Minyoung Kim, Gyeongnam Park, Sungyup Jung & Eilhann E. Kwon
Animal manure is not just a waste problem anymore. A new scientific review shows that when livestock manure is turned into biochar through controlled heating, it can become a powerful, low cost material for cleaning toxic pollutants from wastewater.
Turning waste into clean water
The livestock industry generates enormous volumes of manure every year, creating serious challenges for storage, odor control, greenhouse gas emissions, and the risk of contaminating soil and water with pathogens and nutrients. At the same time, many industrial and agricultural activities release stubborn contaminants including dyes, antibiotics, and heavy metals that current wastewater treatment plants struggle to remove. The new study reviews how converting animal manure into biochar can tackle both problems at once by transforming a difficult waste into a valuable tool for water purification.
“Manure has long been viewed as a liability in intensive livestock systems, but our work shows it can be redesigned as part of the solution,” says corresponding author Eilhann E. Kwon of Hanyang University in Seoul. “By turning animal waste into functional biochar, we can help clean wastewater while reducing the environmental burden of manure management.”
What is animal manure biochar?
Biochar is a carbon rich, porous material produced when biomass is heated in the absence of oxygen, a process known as pyrolysis. In the case of livestock operations, typical feedstocks include cattle, sheep, swine, chicken, rabbit, or goat manure, often mixed with bedding materials such as straw or grass. Because animal manure contains higher levels of nitrogen, phosphorus, calcium, magnesium, potassium, and other inorganic elements than many crop residues, the resulting biochar has distinctive surface chemistry and mineral content.
These features give manure derived biochar a combination of high surface area, tunable pore structure, and abundant reactive functional groups that can bind pollutants. Mineral phases such as carbonates and phosphates, together with surface groups like carboxyl and hydroxyl, support mechanisms ranging from electrostatic attraction and hydrogen bonding to ion exchange, surface complexation, and even mineral precipitation.
How it removes hazardous pollutants
The review shows that animal manure biochar can effectively capture both organic and inorganic contaminants that are difficult to treat using conventional biological processes. For toxic dyes used in textiles, paper, plastics, leather, and pharmaceutical industries, manure based biochars remove color and associated toxicity through a mix of pore filling, electrostatic interactions, hydrogen bonding, and so called electron donor–acceptor interactions between aromatic dye molecules and graphitic carbon domains. In several studies, sheep manure biochar achieved notably high adsorption capacities for common dyes such as methylene blue, methyl orange, and malachite green, outperforming biochars made from other animal manures.
Antibiotics represent another major concern because they persist in water, foster antimicrobial resistance, and can disrupt ecosystems and human health even at low concentrations. The authors report that swine, bovine, and rabbit manure biochars can adsorb widely used drugs including tetracycline, ciprofloxacin, and levofloxacin, with performance controlled by pH, pore structure, and the abundance of oxygen containing surface groups. In many cases, adsorption is driven by a combination of hydrophobic interactions, hydrogen bonding, and electron donor–acceptor interactions between the antibiotic molecules and aromatic domains on the biochar surface.
For heavy metals such as lead, copper, and cadmium, manure biochar offers additional advantages. The high ash content and naturally occurring carbonate and phosphate species promote the formation of insoluble metal precipitates inside the biochar matrix, while ion exchange and surface complexation at carboxyl and hydroxyl sites provide further binding. In comparative tests, animal manure biochars often matched or exceeded the adsorption capacity of commercial activated carbon or zeolite for certain metals, despite being produced from low cost wastes.
Engineering biochar for real world use
A key message of the review is that the performance of manure derived biochar can be tuned through both pyrolysis conditions and post treatment. Slow pyrolysis at moderate to high temperatures typically increases ash content and promotes precipitation based removal of metals, whereas lower temperatures preserve more functional groups that support complexation and hydrogen bonding. Physical activation with steam, carbon dioxide, or hydrogen peroxide can open pores and introduce additional oxygen containing groups, while chemical activation with acids or alkalis further enhances surface functionality and adsorption capacity.
Metal impregnation, especially with iron oxides, can make biochar magnetic for easier recovery and improve the removal of certain metals through additional precipitation and electrostatic binding. However, the authors note that high temperature processes and chemically intensive activation steps require careful evaluation of energy use, costs, and secondary waste generation before large scale deployment.
From concept to application
The study concludes that animal manure biochar is a promising candidate for integration into advanced treatment stages at wastewater treatment plants and for on farm or decentralized water treatment systems. Because manure is continuously produced in large quantities and often costly to manage safely, converting it into engineered biochar could close loops between agriculture, energy, and water management.
“Manure derived biochar offers a rare win–win opportunity,” Kwon says. “It helps control pollution from livestock production while providing an affordable material to clean contaminated water, but future work must focus on scaling up, regeneration strategies, and ensuring safe long term use.”
By offering pollutant specific guidance on biochar production and modification, the authors aim to accelerate the adoption of manure based biochar in practical wastewater treatment and to inspire new research on coupling waste valorization with environmental protection.
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Journal reference: Lee S, Kim M, Park G, Jung S, Kwon EE. 2025. Animal manure biochar for the removal of hazardous pollutants from wastewater. Biochar X 1: e003
https://www.maxapress.com/article/doi/10.48130/bchax-0025-0006
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Biochar X is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
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Method of Research
Literature review
Subject of Research
Not applicable
Article Title
Animal manure biochar for the removal of hazardous pollutants from wastewater
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