Innovative use of dissolved air flotation with biosorption as primary treatment to approach energy neutrality in WWTPs

This paper presents two types of dissolved air flotation application together with biosorption (the ‘Captivator^® system’) as primary treatments. In the first instance, the Captivator^® system is the sole primary treatment for a new plant installation and helps to gain 65% more biogas while requiring only 44% of aeration for COD oxidation, compared to a conventional process with a primary clarifier. In the second application, the Captivator^® system is used to enhance the existing primary treatment for plant capacity expansion. With digested anaerobic sludge recycled as an additional adsorbent, the Captivator^® system in the second application increases the biogas yield by 52% and only generates 59% excess sludge. Overall, the Captivator^® system would help WWTPs to approach energy neutrality by diverting more organics for biogas production and reducing the energy requirements for aeration. In addition, it would help to reduce the installation footprint for primary treatment and save considerable capital cost by eliminating the sludge thickening process.