Removal of Formaldehyde from Trickling Liquid in a Biotrickling Filter

In the biodegradation of Formaldehyde gas with a biotrickling filter, a portion of Formaldehyde is solved in the recirculating trickling liquid. As a consequence, the treatment efficiency is limited. The study explored the feasibility of removing the liquid-phase formaldehyde by inducing chemical reactions in the trickling liquid. Experiments were conducted to test three chemicals (sodium sulfite Na₂SO₃, sodium bisulfite NaHSO₃, and ammonium chloride NH₄Cl), which were applied in the trickling liquid, respectively, to react with the formaldehyde. The formaldehyde removal efficiencies were compared and the optimal reaction Molar ratios were investigated. The results showed that Na₂SO₃ brought the highest Formaldehyde removal efficiencies among the three chemicals and the optimal reaction Molar ratio of Na₂SO₃ and Formaldehyde was 3:1. Under the condition, the removal efficiency of the liquid-phase Formaldehyde was high up to 99.91%.