Production and characterization of liquid fertilizer from urban sewage biological sludge

Today, sewage sludge disposal methods include drying, burning and application in land, but each of these methods has its own vulnerability. Sewage sludge management is difficult not only because of high levels of production, but also because of high concentrations of heavy metals and pathogens. Research has shown that the transfer of sewage sludge to organic fertilizers, including organic fertilizer, is due to its many advantages, including less heavy metals, easy to use with irrigation systems, faster absorption by plants, and increased their growth efficiency etc. which have been very much considered. The purpose of this study was to investigate the properties of sewage sludge and the liquid fertilizer produced from it.

In this study, biological sludge was transformed into liquid fertilizer using a 0.25 molar solution. Characterization of biological sludge and liquid fertilizer by conducting heavy metal concentration tests (Zn, Pb, Cd, Cr, Ni, Fe and Cu), total nitrogen, total phosphorus, soluble potassium, total sodium concentration, electrical conductivity and pH was done.

The results showed that total nitrogen, soluble potassium, heavy metals concentration decreased with increasing of organic matter extraction from sludge whereas, the amount of phosphorus, total sodium content, electrical conductivity and pH increased.

The results of this study showed that the liquid fertilizer produced from sewage sludge due to its characteristics can be used as a soil modifier in agricultural sector.