Carbon supplementation in domestic sewage via mixing with paint booth effluent: Influence on the performance of bioremediation and algal biomass production from high-rate algal ponds

The paint booth effluent (PBE) was used as a carbon supplement to evaluate the treatment of domestic sewage (DS) via microalgae biotechnology. The present study aimed to assess the performance of different mixtures of PBE and DS in the treatment and production of algal biomass in high-rate algal ponds (HRAPs), seeking to determine the optimal mixture between the effluents. The blends were: D1 (0% PBE, 100 % DS), D2 (18.75 % PBE, 81.25 % DS), D3 (37.5 % PBE, 62.5 % DS), D4 (56.25 % PBE, 43.75 % DS) and D5 (75% PBE, 25 % DS). As a result, in the D2 blend, with better carbon, nitrogen, and phosphorus ratio, there was a higher primary and total biomass productivity (0.08 g chl-alpha/m2.day and 2.0 g VSS/m2.day). The regression adjustment corroborated the results of the D2 mixture, showing PBE dosages between 18 and 25 % as better for algal growth. The insertion of PBE in the medium positively affected the bioremediation performance, increasing the removals with the addition of PBE. The nutrient and organic matter removal efficiencies ranged from values close to 50 %, of total organic carbon in the D1 mixture, and reaching 100 % in the removal of ammoniacal nitrogen. The D2 mixture stands out with the highest nitrogen recovery via the assimilation of organic nitrogen, reaching 19 % more in relation to the initial value. Thus, PBE contributed to the supply of organic carbon to the biomass, favoring the consortium between algae and bacteria.