Abstract
Recently, Egypt is facing serious problems caused by the deterioration of effluent quality of many wastewater treatment plants (WWTP) especially in rural areas. Unexpected rapid increase in population associated with the increase of organic loading are the main factors causing the failure in operation for many WWTPs. Absence of periodic maintenance and lack of operators’ experience in these rural areas make the situation worse. Many WWTP are recently under rehabilitation and upgrading for the above reasons, however decision makers are facing a real challenge due to the space-limit in many cases. The integrated fixed film activated sludge (IFAS) system has recently proved to be an effective choice to expand the WWTP capacity for growing communities, enhance nitrogen removal and comply with more stringent effluent limits with small footprint. In this research, an IFAS pilot-scale reactor is constructed to optimize its application in upgrading conventional activated sludge (CAS) plants. The effect of carrier position, hydraulic retention time (HRT) and organic loading rate (OLR) on the biological treatment efficiency and nutrient removal compared to CAS process are studied. IFAS configurations with no media, vertical position and cross flow media position are tested with 4, 8 and 12 hours retention times and organic loading rates of 0.84 and 1.44 Kg COD/m 3 .day. Keywords: Integrated fixed film IFAS, biological nitrogen removal, honeycomb PVC media DOI : 10.7176/CER/11-2-06 Publication date :March 31 st 2019
Highlights
Wastewater treatment systems depend mainly on the biological action of different types of microorganisms, primarily bacteria, for removing dissolved and suspended organic matter (Schultz 2005; Ahmed et al 2013)
Whereas in attached growth processes the microorganisms are attached to some inert medium, such as rock, slag or specially designed ceramic or plastic materials applied in Trickling Filters (TF) and Rotating Biological Contractors (RBC)
The hydraulic retention time (HRT) was adopted to be 12 hours with a flow rate of 1.67 l/hr. This phase is divided into three stages: stage one was operated without media as a simulation of conventional activated sludge system, in stage two, a honeycomb structured PVC media was added to the reactor in a vertical flow position covering 50% of the reactor volume and as a simulation of an Integrated Fixed-film Activated Sludge (IFAS) system and in stage three the position of media was changed to cross flow position
Summary
Wastewater treatment systems depend mainly on the biological action of different types of microorganisms, primarily bacteria, for removing dissolved and suspended organic matter (Schultz 2005; Ahmed et al 2013). Biological treatment processes can be principally divided into aerobic and anaerobic processes where they can be further subdivided into suspended-growth processes, attached-growth processes or a combination of both (Ahmed et al 2015; Safwat et al 2018). The microorganisms responsible for treatment are maintained in suspension by appropriate mixing methods as in Activated sludge process (ASP), sequencing batch reactor (SBR), stabilization ponds and extended aeration systems. Suspended growth processes provide operation flexibility and high degree of treatment quality while attached growth processes are inherently stable and resistant to organic and hydraulic shock loadings. The combination of both processes is widely applied to achieve the advantages of both processes as in Integrated Fixed-film Activated Sludge (IFAS) process (Weerapperuma et al 2005; Safwat 2018)
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