Effect of FeCl 3 concentration in chemically enhanced primary treatment on the performance of a conventional wastewater treatment plant. A case study

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Toxic/hazardous substances & environmental engineering, 2024-01, Vol.59 (1), p.33-39
• Main Authors: Ruiz, L M, Checa, A, Perez, J I, Torre-Marín, J M, Muñoz-Ubiña, A, Gómez, M A
• Format: Article
• Language: English
• ISSN: 1093-4529; 1532-4117
• DOI: 10.1080/10934529.2024.2328449

The effect of coagulant dosage in a chemically enhanced primary treatment (CEPT) on the performance of a conventional wastewater treatment plant (WWTP) has been investigated. Lab-scale experiments simulations were carried out in order to evaluate the effect of coagulant addition on the primary settling performance. In these experiments, FeCl was used as coagulant. Later, the WWTP was theoretically simulated using a commercial software (WEST®) to evaluate the effect of coagulation/flocculation on the global system, based on the results obtained at lab-scale. According to these results, the CEPT modifies the organic matter balance in the WWTP, decreasing the contribution of readily (S ) and slowly (X ) biodegradable fractions of COD to the aerobic biological process up to 27.3% and 80.8%, respectively, for a dosage of FeCl of 24 mg L . Consequently, total suspended solids in the aerobic reactor and the secondary purged sludge decreased up to 33% and 13%, respectively. However, the influence on effluent quality was negligible. On the contrary, suspended solids concentration in the sludge to be treated by anaerobic digestion increased, mainly regarding the S and X fractions, which caused an 8.1% increase in biogas production potential, with approximately 60% of CH concentration.