Loofah Sponges as Bio-Carriers in a Pilot-Scale Integrated Fixed-Film Activated Sludge System for Municipal Wastewater Treatment

Abstract

Fixed-film biofilm reactors are considered one of the most effective wastewater treatment processes, however, the cost of their plastic bio-carriers makes them less attractive for application in developing countries. This study evaluated loofah sponges, an eco-friendly renewable agricultural product, as bio-carriers in a pilot-scale integrated fixed-film activated sludge (IFAS) system for the treatment of municipal wastewater. Tests showed that pristine loofah sponges disintegrated within two weeks resulting in a decrease in the treatment efficiencies. Accordingly, loofah sponges were modified by coating them with CaCO3 and polymer. IFAS pilot tests using the modified loofah sponges achieved 83% organic removal and 71% total nitrogen removal and met Vietnam’s wastewater effluent discharge standards. The system achieved considerably high levels of nitrification and it was not limited by the loading rate or dissolved oxygen levels. Cell concentrations in the carriers were twenty to forty times higher than those within the aeration tank. Through 16S-rRNA sequencing, the major micro-organism types identified were Kluyvera cryocrescens, Exiguobacterium indicum, Bacillus tropicus, Aeromonas hydrophila, Enterobacter cloacae, and Pseudomonas turukhanskensis. This study demonstrated that although modified loofah sponges are effective renewable bio-carriers for municipal wastewater treatment, longer-term testing is recommended.

Pilot-scale study based on integrated fixed-film activated sludge process for cement industrial wastewater treatment

“…The COD and BOD removal efficiency of Luffa media were 86% and 88%, respectively . The performance of Luffa sponges in our experimental study was not perfect enough as it was lower than COD removal efficiency of other studies that exceeded 90% (Ruiz-Marín et al, 2009;Dang et al, 2020). This variation in COD removal was due to the low hydraulic retention time (24 h) performed in our experimental study.…”

“…An additional modification was performed to increase the number of bacteria in the IFAS basin by increasing the surface area. Sponges were coated by plasticized polymer as Acrylic-Styrene polymer (Dang et al, 2020). First, the Acrylic-Styrene polymer was mixed with water to form a solution, and then sponges were soaked for 1 h, Luffa sponges were dried at 25 o C for 24 h to be ready for use, as shown in Figure 1 .…”

“…So searching for alternative IFAS media was necessary to overcome plastic media disadvantages. Several natural materials were used as IFAS media, such as zeolite, volcanic ashes, giant reed, gravel, cotton, and Luffa (Dang et al, 2020). In this paper, we will compare the performance of the IFAS process using Polyurethane sponges (PU) as an artificial media and Luffa sponges as a natural bio-carrier.…”

“…Luffa sponge is biodegradable, so increasing fiber's durability and service age was improved by immersing it in a lime solution to make it much harder. To increase the adhesion between Luffa fibers and microorganisms, Luffa must be coated with an acrylic-styrene polymer (Dang et al, 2020). PU sponge is a high-performance adhesive; it has high mechanical strength, rough surface, large surface area, and high adhesion to biomass.…”

Wastewater Treatment Costs: A Research Overview through Bibliometric Analysis

“…Appropriate water management aimed at increasing the supply of water necessarily involves the use of wastewater treatment. [18][19][20]. Wastewater management is expensive and poses problems regarding how to finance it and how to reduce treatment costs [21].…”