Amin Goli - Chemical Engineering Department, Islamic Azad University Branch of Quchan, Quchan, Iran
Ahmad shamiri - Chemical & Petroleum Engineering Department, Faculty of Engineering, Technology & Built Environment, UCSI University, ۵۶۰۰۰ Kuala Lumpur, Malaysia
susan khsroyar - Chemical Engineering Department, Islamic Azad University Branch of Quchan, Quchan, Iran
amirreza Taleikhozani - Department of Cancer proteomics, Shiraz University of Medical Sciences, Shiraz, Iran
Reza Sanaye - Department of Medical Nanotechnology, Shiraz University of Medical Sciences, Shiraz, Ir
Kourosh Azizi - Department of Medical Entomology, School of Health, Shiraz University of Medical Sciences, Shiraz, Ira

Dairy industries have grown tremendously in many regions around the world due to the growth of demand for milk-relatedproducts. Dairy industries release wastewater containing high chemical oxygen demand (COD), biological oxygen demand (BOD),nutrients, in addition to organic and inorganic substances. Such wastewater, if improperly treated, severely pollutes water resources.For many years, anaerobic–aerobic processes have been used to remarkable effect in the treatment of dairy industry wastewater.Previously, a large portion of wastewater treatment was carried out in conventional anaerobic–aerobic treatment units. Nowadays,high-rate anaerobic–aerobic bioreactors are progressively employed for treating wastewater with high COD content. This paperreviews dairy wastewater sources, their production, and characteristics. Furthermore, different types of high-rate anaerobic–aerobicwastewater treatment methods currently available, including aerobic and anaerobic bioreactors over and above hybrid anaerobic–aerobic bioreactors, are discussed. The strong points and the weaknesses of different individual and combined anaerobic and aerobicbioreactors are highlighted; they are then compared to point out future areas of investigation for full usage and application of thesemethods for wastewater treatment. The comparison demonstrates that using an integrated bioreactor is advantageous in treatinghighly polluted industrial wastewater. The combination of aerobic and anaerobic degradation pathways in an individual bioreactorcan enhance overall degradation efficiency. Furthermore, this combination appears as an attractive alternative from the technical,economic, and environmental perspectives, especially wherever space is a limiting factor.

Dairy product, Industrial dairy wastewater, Anaerobic–aerobic treatment, Anaerobic–aerobic bioreactors, Wastewater treatment