Experimental Study on Cow Manure: From Outhouse into House

Manure is the second largest source of greenhouse gas (GHG) emissions from agriculture. A sufficient method for handling manure is needed. Meanwhile, the need for construction materials and economic and population growth are rising. This study aims to tackle both problems by utilizing cow manure mixed with clay as bricks using wet torrefaction and solid–liquid separation to reduce the amount of untreated manure and supply construction materials with greener and improved clay bricks. Cow manure was treated using a wet torrefaction process, heating the manure at 100, 120, and 140 °C, and then left to dry. The dried manure was then mixed with clay, molded, dried, and then baked to produce baked red clay bricks. The bricks were then tested for their compression strength and water absorptivity to determine the relationship between wet torrefaction parameters and brick characteristics. After the tests were completed, it was found that mixing cow manure into bricks increased the compression strength by up to 400% compared to pure clay brick and water absorptivity by up to 150%. Even though the strength of these bricks was increased, utilizing them as conventional construction material is not recommended. Instead, breathable façade material is more favored. Alongside solid products, torrefaction also produced liquid products rich in nutrients. Previous research showed that the nutrient content was sufficient to be made as liquid fertilizer. These results showed the possibility of implementing torrefaction of cow manure to reduce waste and upgrade the products’ value.