Phosphorus recovery from the sludge generated from a continuous bipolar mode electrocoagulation (CBME) system

Abstract

Phosphorus is known to be a limited non-renewable resource. Phosphorus is obtained from phosphate rock, which is likely to be depleted in the next few decades. Therefore, it is very important to find alternate sources of phosphorus from which phosphorus can be recycled and recovered. This study focuses on the recovery of phosphorus from the sludge generated from a continuous bipolar mode electrocoagulation (CBME) system, used for treating a palm oil mill effluent (POME). The sludge generated from the CBME system is leached with oxalic acid and sulphuric acid for phosphorus recovery with and without thermal treatment. Acid leaching was carried out at various time intervals using various liquid/solid (L/S) ratios of acids and sludge. The CBME system caused a 73% removal of phosphorus from POME, where phosphorus is precipitated in sludge as iron phosphates or adsorbed as phosphates depending on the pH in the system. Acid leaching resulted in nearly 85% recovery of phosphorus with both sulphuric acid and oxalic acid for sludge combusted at 900 °C. Statistical analysis was carried out to find the significance of the operational conditions on the phosphorus yield. Acid leaching results in the formation of orthophosphates, which can be used as a raw material for synthesis of chemical fertilizers.

Emerging trends in POME treatment and applications: chemical and biotechnological aspects

“…POME, even after pre-treatment, is rich in nutrient parameters such as nitrogenous and phosphorus compounds (Yashni et al, 2020). A recent study has reported the recovery of phosphorus from POME through combustion of the sludge, followed by acid leaching and extraction using sulphuric and oxalic acids (Damaraju et al, 2019).…”

“…Among the many and more recent treatment alternative techniques are the biological options of (an)aerobic therapies and chemical techniques. While some of the techniques of choice must, within a reasonable timeframe, offer the best results in terms of waste management -reduction in chemical oxygen demand (COD) and biochemical oxygen demand (BOD), others assist in useful product recovery including but not limited to biofuels, biofertilizers, and bioproducts (Ahmad et al, 2020;Damaraju et al, 2019;Hope & Gideon, 2015;Ndubuisi-Nnaji et al, 2020). Various methodologies have been studied for developing low-priced and active treatment techniques, including the integrated anaerobic-aerobic bioreactor (IAAB) system.…”

Sewage Sludge Thermal Treatment Technologies with a Focus on Phosphorus Recovery: A Review

“…Gorazda et al [62] reported a combustion temperature of 950 °C as the best condition for downstream phosphorus extraction from ash. Acid leaching resulted in nearly 85% recovery of P with both sulphuric acid and oxalic acid for sludge combusted at 900 °C [63]. Kasina et al [64] investigated the chemical and mineralogical characteristics of ISSA obtained from Veolia's fluidized bed incinerator for SS (Pyrofluid) at 850-900 °C and concluded that elements which are characterized by high melting temperatures concentrate in the ISSA, while elements that are characterized by lower melting temperatures (e.g.…”