Peanut Shell Biochar, an Eco-Friendly Solution to Absorb Phosphate from Wastewater

Phosphate-contaminated water not only increases the cost of water treatment but can also lead to harmful algal blooms that pose serious health risks to humans. This is where a simple yet smart technology called biochar offers a promising solution.

What is Biochar?

Imagine peanut shells — usually discarded as waste — being transformed into a powerful pollutant-absorbing material. Biochar is a type of charcoal produced by heating organic materials (such as peanut shells) in a low-oxygen environment. It boasts a large surface area, porous structure, and high carbon stability — all of which make it highly effective for absorbing contaminants.

However, there’s a challenge. Since biochar often comes in powder form, it’s difficult to separate from water after use. To address this, an innovation called magnetic biochar was developed — biochar modified with magnetic materials, allowing it to be easily removed from water using a magnet.

Two Methods for Modifying Biochar

To make biochar magnetic and enhance its phosphate absorption capacity, two main modification methods are used:

1. One-Step Method

In this method, peanut shells are first soaked in a solution containing metals like magnesium (Mg) and iron (Fe), then pyrolyzed (burned) to create biochar. The result? Biochar containing MgO and Fe₃O₄ particles. This combination not only makes the biochar magnetically responsive but also significantly boosts its phosphate binding ability. Additionally, the surface structure and functional groups of the biochar become more active, improving its overall performance.

2. Electrochemical Method

Unlike the one-step method, this technique uses electric current to embed magnesium and iron into the biochar. The end product contains magnetic compounds such as MgFe₂O₄ and Fe₃O₄. Although this method does not drastically alter the surface structure of the biochar, it is still effective at absorbing phosphate due to the chemical interactions of the compounds formed during electrolysis.

Which Method is More Effective?

Comparative studies show that biochar produced via the one-step method has a higher phosphate adsorption capacity. Why? Because the chemical processes during pyrolysis help form surface structures and functional properties that are more efficient at "capturing" phosphate. Especially when the Fe and Mg combination is carefully balanced, this method consistently delivers superior performance.

Transforming peanut shell waste into a pollutant-absorbing material is not just a smart idea — it’s a real-world application of sustainable innovation. Through simple techniques like the one-step or electrochemical method, we can create local solutions to tackle global problems like water pollution.

Imagine if every household or community could convert organic waste into functional biochar — cleaner environments, reduced waste, and improved water quality. A small step with a big impact.

Discover more about SAWA’s Innovative Biochar production and its impact on sustainable farming.

Explore SAWA Biochar