Experimental investigation of biofilm carriers of varying shapes, sizes, and materials for wastewater treatment in fixed bed biofilm reactor: a qualitative study of biocarrier performance

Abstract

BACKGROUND Biofilm carriers were introduced in the early 1990s mainly to abate chemical oxygen demand (COD). However, studies have continued investigating few biocarriers repeatedly, without studying a large number of carriers in a single study under similar conditions. RESULTS The current study investigated the performance of nine synthetic and eight natural biofilm carriers for 7 days of palm oil mill effluent (POME) treatment in terms of COD removal. A fixed bed biofilm reactor (FBBR) was 100% packed with biocarriers and operated at 35 °C. Performance based on the 7th day COD removal could be ranked in the following order: green ammonia absorption stone (91%), K1 micro (88%), coral sand (87.8%), volcanic stone (86.6%), Micro Media (85.5%), 1.6 cm BioBall (85%), pebble (82.4%), porous ceramic ring (82.3), K1 (82.1%), non‐porous ceramic ring (80.9%), brown ammonia absorption stone (78.6%), biological filter (77.7%), Ultra Media (76.8%), blue media (69.3%), 3.0 cm BioBall (68.8%), 2.5 cm BioBall (66.5%), and loofah sponge (63%). CONCLUSION The smallest carrier, K1 micro, yielded the highest COD removal (88%) on day 7 among the other synthetic carriers, while green ammonia absorption stones provided the highest quality effluent from day 1 (3565 mg COD L−1) to day 7 (780 mg COD L−1) and delivered the shortest start‐up compared with all natural and synthetic carriers. The discussion revealed that all carrier functionalities (i.e., scale, shape, surface pores, roughness, material, surface area, porosity, and durability) play a key role in deciding carrier quality. The current study also introduced ‘carrier efficiency limit’, which refers to the carrier's capacity to entrap biomass and immobilize microorganisms. © 2022 Society of Chemical Industry (SCI).

Improvement of MBBR Performance by the Addition of 3D-Printed Biocarriers Fabricated with 13X and Bentonite

“…It is worth mentioning that the research of Chioti et al (2022) [15], who studied the efficiency of Kaldnes K1 commercial biocarriers and 3Dprinted biocarriers with 13X and bentonite in aerobic wastewater treatment performed in lab reactors of 150 mL active volume, has also shown a remarkable efficiency in wastewater treatment. According to other researchers [16], the synthetic biofilm carriers showed unstable COD removal rates, in contrast to the natural biofilm carriers that did not present any instability. This is due to the surface properties of the natural biofilm carriers, such as surface pores and roughness.…”

“…Based on Figure 3 and on the influent/affluent COD values, it can be concluded that there is an excellent effluent quality in all three cases, with a removal rate of 88% for the control MBBR, 92% for MBBR K1 (slightly increased) and of 84% for MBBR 3D (slightly decreased). Other researchers [16] have concluded that COD removal when using synthetic biocarriers (including Kaldnes K1 biocarriers) in smaller-scale experiments is unstable. However, this was not found in the large-scale experiments of this research, as the COD removal was increasing steadily during the operating time of the unit.…”

“…This is due to the surface properties of the natural biofilm carriers, such as surface pores and roughness. According to Alamshawee et al (2022) [16], the Kaldnes K1 biocarriers delivered the shortest start-up in the first 3 days.…”

Improvement of MBBR Performance by the Addition of 3D-Printed Biocarriers Fabricated with 13X and Bentonite

“…It is worth mentioning that the research of Chioti et al (2022) [16], who studied the efficiency of Kaldnes K1 commercial biocarriers and 3D-printed biocarriers with 13X and bentonite in aerobic wastewater treatment performed in lab reactors of 150 mL active volume, has also shown remarkable efficiency in wastewater treatment. According to other researchers [17], the synthetic biofilm carriers showed unstable COD removal rates, in contrast to the natural biofilm carriers that did not present any instability. This is due to the surface properties of the natural biofilm carriers, such as surface pores and roughness.…”

Biosand Reactors for Municipal and Industrial Wastewater Treatment: Status Quo, Challenges and Opportunities

“…The main functions of the sand particles in BSRs are to trap solids and provide large surface areas and robust biofilm attachment sites for the microbial communities responsible for biodegradation of pollutants in WW [15]. It has been shown that the extensive rough surfaces of sand grains promote biofilm growth more effectively than synthetic biofilm attachment alternatives [15]. In BSRs, contact between the microbial communities and the pollutants takes place as the WW passively permeates through the interpore spaces in the sand [16].…”