Downflow Hanging Sponge System: A Self-Sustaining Option for Wastewater Treatment

Maharjan, Namita; Hewawasam, Choolaka; Hatamoto, Masashi; Yamaguchi, Takashi; Harada, Hideki; Araki, Nobuo

doi:10.5772/intechopen.94287

Cited by 6 publications

(2 citation statements)

References 78 publications

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“…In the 1980s, Japanese researches began investigating an interesting application of a sponge material made of flexible or hardened polyurethane. They developed a technology of an Upflow Anaerobic Sludge Blanket (UASB) reactor combined with a Down-flow Hanging Sponge (DHS) reactor for treatment of low-concentrated domestic or municipal wastewater [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Bundy et al [ 26 ] investigated the use of a four-module reactor filled with foams with different pore contents (20 or 45 pores per inch) for direct purification of domestic wastewater containing N–NH 4 + in an amount of approx.…”

Section: Introductionmentioning

confidence: 99%

Polyurethane Foams for Domestic Sewage Treatment

Dacewicz

Grzybowska-Pietras

2021

Materials

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The aim of the study was to assess the possibility of using polyurethane foams (PUF) as a filling of a foam-sand filter to directly treat domestic sewage with increased content of ammonium nitrogen and low organic carbon to nitrogen ratio (C/N). The study compared performance of two types of flexible foams: new, cylinder-shaped material (Novel Foams, NF) and waste, scrap foams (Waste Foams, WF). The foams serving as a filling of two segments of a foam-sand filter were assessed for their hydrophobic and physical properties and were tested for their cell structure, i.e., cell diameter, cell size distribution, porosity, and specific surface area. The study accounted also for selected application-related properties, such as hydrophobicity, water absorption, apparent density, dimensional stability, amount of adsorbed biomass, and the possibility of regeneration. Cell morphology was compared in reference foams, foams after 14 months of the filter operation, and regenerated foams. The experimental outcomes indicated WF as an innovative type of biomass carrier for treating domestic sewage with low C/N ratio. SEM images showed that immobilization of microorganisms in NF and WF matrices involved the formation of multi-cellular structures attached to the inner surface of the polyurethane and attachment of single bacterial cells to the foam surface. The amount of adsorbed biomass confirmed that the foam-sand filter made up of two upper layers of waste foams (with diameters and pore content of 0.50–1.53 mm and 53.0–63.5% respectively) provided highly favorable conditions for the development of active microorganisms.

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Section: Introductionmentioning

confidence: 99%

Polyurethane Foams for Domestic Sewage Treatment

Dacewicz

Grzybowska-Pietras

2021

Materials

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“…In the literature, much attention is paid to a simple method of PUF regeneration by rinsing adsorbed pollutants with distilled water [ 8 ], as well as their low investment cost and mechanical strength. In recent years, polyurethane foams have been studied as carriers for immobilized bacterial cells to remove crude oil from seawater [ 9 ], decolorize or bioremediate industrial wastewater [ 10 , 11 ], treat dairy wastewater [ 12 ], remove toxic pollutants from industrial wastewater [ 4 ], as well as for municipal wastewater treatment [ 2 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Waste Polyurethane Foams as Biomass Carriers in the Treatment Process of Domestic Sewage with Increased Ammonium Nitrogen Content

Dacewicz

Lenart‐Boroń

2023

Materials

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In order to understand the mechanisms of microbial growth on waste polyurethane sponge materials, their effectiveness as biomass carriers in domestic sewage with increased ammonium nitrogen content treatment was assessed. Comparative experiments were carried out in microreactors under steady conditions of batch culture, which allowed for an assessment of different carriers, in the form of flexible foams, rigid foams, and flexible foams placed in full casings. In the studies conducted in continuous cultures, biomass carriers selected in batch culture were used as fillings in the column model. The structure of the microbial community inhabiting the spongy material was determined and the pollutant-removing process from real domestic sewage was assessed. Analyzes using the Illumina sequencing technique allowed for demonstrating that Nitrosomonas and Nitrospira were the predominant nitrifiers in the biomass carrier in the form of waste polyurethane foams (PUF). It was found that anammox bacteria, the presence of which—as unidentified Planctomycetes—was confirmed in the polyurethane sponge material, were also responsible for the high removal of N-NH4+. Burkholderia and Sphingopyxis phyla were identified as the dominant denitrifying bacteria involved in the treatment of domestic sewage with increased content of ammonium nitrogen. The biomass carrier in the form of waste PUF placed additionally in full casings proved to be more beneficial for the proliferation of bacteria involved in nitrification and denitrification processes. On the other hand, waste foams without casings proved to be more suitable for the growth of microorganisms known to perform partial denitrification and may accumulate nitrites (Staphylococcus, Dokdonella). Additionally, the presence of Devosia and Pseudonocardia, which participated in the phosphorus removal process, was found in the waste PUR foams.

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