Biological treatment of industrial wastewater containing formaldehyde and formic acid.

Abstract

The biological treatment of wastewater from an aminoplastic resin-producing industry was studied in a pre-denitrifica- tion system. This study reports results on the removal of organic matter and nitrogen compounds from wastewater which contained high levels of formaldehyde and formic acid. The formaldehyde concentration in the feed varied between 2 087.0 and 2 200.0 mg/ℓ, the mean removal being 99.9%. The mean efficiency of formic acid removal was 99.7%, and its concentration in the feed ranged between 1 384.6 and 1 513.9 mg/ℓ. The total organic carbon (TOC) values in the feed varied from 1 423.0 to 1 599.5 mg/ℓ, corresponding to an organic loading rate of about 0.20 kg TOC/m3•d. High TOC removal was achieved, around 92.0%. With regard to nitrogen compounds, the total Kjeldahl nitrogen (TKN) concentration in the feed ranged between 467.8 and 492.3 mg/ℓ. The applied nitrogen loading rate was around 0.06 kg TKN/m3•d, and the mean percentage of TKN removal was 76.7%.