Biproducts

Biproducts, commonly referred to as by-products, are secondary products generated in a manufacturing or chemical process alongside the main product. They arise because many reactions and separations yield multiple substances. By-products can have value, and may be recovered, sold, or repurposed. If two products are of similar value, they are often called co-products rather than by-products.

Whether a by-product is retained, discarded, or valorized depends on economics, purity requirements, and market demand. Some by-products serve as useful feedstocks for other processes; others require treatment or disposal as waste. Recovering valuable by-products can improve overall yield, reduce waste, and lower production costs, though it may add equipment or purification steps.

Industry examples include: lignin recovered from paper pulping as a potential chemical or fuel; distillers grains with solubles (DDGS) from ethanol production used as animal feed; glycerol produced alongside biodiesel with applications in chemicals and fuels; and various refinery by-products that become fuels or chemical inputs after processing.

Environmental and regulatory considerations affect by-product management. Some by-products are regulated as wastes or hazardous materials unless reused. Proper handling, storage, transport, and emissions controls are required, while corporate and regulatory programs increasingly promote waste valorization and a circular economy approach.

See also: waste valorization, process integration, circular economy.