There are few recent researches that attempted to investigate the mechanism of FOG deposit formation.
To measure the pH, sample of FOG deposit was mixed with 1:1 ratio distilled water and stirred gently.
Pre-weighed samples of wastewater and FOG deposit were kept in the oven at 105[degrees]C for overnight.
Another research reported calcium leaching from concrete pipes to be the main source of increased concentrations of Ca in the FOG deposit samples [7].
Moreover, sodium, potassium and calcium ions are contributors to the formation of FOG deposit through the saponification reaction of FFAs and TAGs.
Test FOG deposit Wastewater ph 5.1 6.4 Moisture 68.1% 98.04% Density 0.9996 g/ml 1.0012 g/ml Calcium (Ca) 1.96 mg/l 25.42 mg/l Sodium (Na) 1.71 mg/l 27.56 mg/l Potassium (K) 0.77 mg/l 12.30 mg/l Silica 0.81 mg/l 9.90 mg/l Iron (Fe) 0.08 mg/l 3.58 mg/l Magnesium (Mg) 0.93 mg/l 2.29 mg/l Aluminum (Al) 0.20 mg/l 1.59 mg/l Copper (Cu) 0.03 mg/l 0.05 mg/l Zinc (Zn) 0.09 mg/l 0.33 mg/l Sulphur 3.25 mg/l 7.35 mg/l Lead (Pb) N.D 0.03 mg/l Arsenic (As) N.D 0.016 mg/l Phosphorus 2.69 mg/l 9.98 mg/l Saturated fat 33.84 g/100g sample 0.05 g/100g Unsaturated fat 30.42 g/100g sample 0.04g/100g Oil & Grease 963 mg/l 919 mg/l Hardness N.D <1 80 mg/l
From Table 1, the low concentration of silica (0.81 mg/l) and high concentration of FOG (963 mg/l) in the deposit sample indicates that the deposit in the wastewater pipelines is mainly consisting of FOG deposits and have insignificant amount of other impurities.