Physicochemical Properties of Biochar Derived from Anaerobic Digestion Effluent from Cheese Factory Drainage.

Physicochemical properties of biochar derived from anaerobic digestion effluent from cheese factory drainage.

Anaerobic digestion technology is a waste treatment process.  It can successfully treat the organic wastes from many industries such as municipal sludge, industrial wastewater, agricultural waste.  Anaerobic digestion effluent (ADE) which is residue of anaerobic digestion process contain sufficient amounts of plant nutrition such as nitrogen, phosphorus and potassium.  Fertilizer effects of liquid part of ADE have been shown in previous studies.  However, usage of solid part of ADE has not been established.  Generally, residues obtained from anaerobic digestion are applied as compost to soils directly. But increasing concerns regarding the contamination potential of toxic substances have necessitated alternative methods.  Pyrolysis of the solid part of ADE to produce biochar has been proposed as a beneficial product.  Therefore, the objective of this study was to investigate the physicochemical properties of biochars derived from anaerobic digestion effluent from cheese factory drainage.

The ADE used in this study was separated for liquid and solid parts. The solid part was pyrolysed at 350, 550, and 800^oC (ADE350, ADE550, and ADE800, respectively). The surface area of the biochars were determined by nitrogen BET. The pH, total carbon, total nitrogen, total phosphorus, ammonium, nitrite, and citric acid-extractable phosphorus of the biochars were analyzed.

The biochar yield rates of ADE350, ADE550, and ADE800 were 45%, 27.5% and 25.4% of the initial dry weight of the solid ADE, respectively. As pyrolysis temperature increased ash content increased, however volatile matter and fixed carbon contents decreased. The results of this study showed that biochar produced at lowest temperature had the lowest yield rate and highest volatile matter content, as seen in other studies.