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The demand for fresh water is increasing daily, requiring industries to take action to reduce the need for fresh water. Winemaking industries represent a massive hydric impact by combining the water consumed and the high volume of wastewater produced. The sun-driven photooxidation process has been widely employed in removing wastewater pollutants. This work employed four photosensitizers, Rose Bengal, AlPcS4, ZnPcS4, and TPP, for water reuse in cellars. A secondary effluent has been investigated as a water matrix. Of all the photosensitizers (PS) employed, ZnPcS4 showed better chemical oxygen demand (COD) (23%) and phenolic (TPh) (81%) removal. The effect of pH and concentration was also assessed for ZnPcS4. The phenolic content removal was found to be highly dependent on the solution’s pH, as alkaline solutions improve the singlet oxygen quantum yield where the use of a pH = 11 reached 42% and 81% of COD and TPH removal. However, a pH higher than 7 showed higher PS bleaching than pH = 7. Three different PS concentrations were evaluated: 3 × 10−6, 5 × 10−6, and 1 × 10−5 mol/L. The optimal PS concentration was found to be 5 × 10−6 mol/L.

Dairy industry wastewater is rich in organic content, presenting a high biodegradability, and therefore biological treatments are widely employed. This study aimed to evaluate biosolids production in three systems: activated sludge (AS), movingbed biofilm reactor (MBBR), and sequencingbatch movingbed biofilm reactor (SBMBBR). Simulated dairy wastewater was used at different organic load rates (OLRs): 1.22, 2.87, and 5.44 gCOD L−1d−1. Besides biosolids production, COD, total carbon (TC), and total nitrogen (TN) removal efficiency was evaluated. Biosolids production was measured in the mixed liquor, carrier-adhered biomass, treated wastewater, and surplus sludge. The operational conditions were kept similar for the three systems, with a carrier filling ratio of 50% for MBBR and SBMBBR. The SBMBBR proved to have better performance in the removal efficiencies of COD, TC, and TN for all OLRs studied. The MBBR presented a similar COD and TC removal efficiency as the SBBR for the two highest OLRs (2.87 and 5.44 gCOD L−1d−1). Concerning biosolids production, the MBBR system produced less biomass and delivered the lowest amount of adhered biomass inside the carriers. The AS treatment generated the highest amount of sludge and offered the worst treatment capability for all OLRs evaluated.

The authors conducted a study on treating synthetic dairy wastewater using aerobic granular sludge (AGS) in a laboratory-scale continuous flow reactor (CFR) system. The system consisted of an anaerobic reactor, an aerobic reactor, and a settling sedimentation tank, with different hydraulic retention times tested over a 90-day period. The study monitored sludge characteristics and effluent treatment performance and found that the system achieved excellent removal rates for chemical oxygen demand and total carbon, exceeding 90%. As a result, the effluent met Portuguese laws for direct release into the water environment. Moreover, the study found that the AGS system improved the sludge sedimentation capacity from 272 to 80 mL/g, demonstrating its effectiveness as a viable treatment alternative for this type of effluent.