Biogranulation and Physical Properties of Aerobic Granules in Reactors at Low Organic Loading Rate and with Powdered Ceramsite Added

Abstract

In wastewater treatment, aerobic granular sludge (AGS) technology is a relatively new alternative to the activated sludge method. The biogranulation of biomass ensues when appropriate environmental conditions in a reactor are ensured, and one of the factors determining this is the organic loading rate (OLR). As a literature review suggests, the optimal values of OLR for AGS technology are in the range of 2.50-7.50 g COD/(dm 3 •d), the aim of the work detailed here was to evaluate the impact of powdered ceramsite on biogranulation in two Granular Sequencing Batch Reactors (GSBRs) in which OLR was equal to just 2.10 g COD/(dm 3 •d) (R1) and 1.0 g COD/(dm 3 •d) (R2). The research was carried out in laboratory scale with using synthetic wastewater containing different concentration of organic compounds. In the course of the research, a more intensive process of biogranulation was noted in reactor R1, and mean diameters of granules on the last day of experimentation were 962 and 274 µm for R1 and R2, respectively. While the organic loading rate equal to 2.10 g COD/(dm 3 •d) could allow granule formation, the results also pointed that lower food-to-microorganism (F/M) ratios favour biogranulation. This parameter was indirectly affected by the application of powdered ceramsite, because the powdered material improved the sludge sedimentation properties (average values of SVI 30 being 30.1±12.8 and 36.9±10.9 cm 3 /g). The result of this was more-limited leaching of biomass from reactors (with average values for MLVSS at 4.37±1.23 and 3.03±0.67 g/dm 3).

The Influence of COD Fraction Forms and Molecules Size on Hydrolysis Process Developed by Comparative OUR Studies in Activated Sludge Modelling

“…Additionally, other studies regarding the development of wastewater treatment technologies and the optimization of the processes have been carried out and implemented. They have concerned issues related to the development of technologies that use activated sludge in various forms [7][8][9][10][11]; the bioaugmentation of reactors [12,13], biofilm, and hybrid techniques [14,15]; and the preliminary preparation and pre-treatment of sewage sludge and back-side waters [16,17]. New research has also covered alternative technologies, e.g., sorption which may be used for the removal of a big amount of organic and inorganic pollutants and which can be used in conjunction with several techniques (such as flocculation-coagulation) [18][19][20].…”

The Impact of Different Powdered Mineral Materials on Selected Properties of Aerobic Granular Sludge

“…The group of physical properties of aerobic biomass includes the morphology and size of granules, spatial structure, sedimentation properties, porosity, specific gravity, density of granules, water content and physical strength [4][5][6][7][8]. The physical parameters of granular biomass are important due to the stability of the granules obtained, but also given the nature of the biological processes by which wastewater is treated [9].…”

“…A number of materials from the first group were used, including powdered activated carbon (PAC) [21,22], dry sewage sludge micropowder [23], granular activated carbon (GAC) [24][25][26][27], and biochar [28]. The mineral materials used to date were zeolite [29], bivalve shell carrier [30,31], yellow earth [32], ceramsite [8,20] and basalt [17]. According the literature [20,23,27,31,32], adding such materials to a reactor results in an improvement of the sedimentation properties of the obtained aerobic granules, as well as allowing the acceleration of microorganism aggregation and the formation of mature granules in a short time.…”

Powdered Ceramsite and Powdered Limestone Use in Aerobic Granular Sludge Technology

“…Most reports on successful granulation have shown that a high OLR is critical to the development and maturation of aerobic granules [ 7 , 8 , 9 ]. Higher OLR facilitates granule formation [ 9 , 10 , 11 , 12 ]. According to a literature review, the optimal OLR of a granular sequencing batch reactor (GSBR) is 2.50 g COD/(L∙d) [ 13 ] or should be in the range 2.50–7.50 g COD/(L∙d) [ 14 , 15 ].…”

“…To date, research on improving AGS technology has involved chemical coagulants [ 17 ], dosage of granule fragments [ 18 , 19 ], and powdered materials, both mineral ( Table 1 ) [ 4 , 11 , 20 , 21 , 22 ] and organic [ 10 , 23 , 24 , 25 , 26 , 27 , 28 ]. It should be emphasized that in addition to the use of metal ions and flocculants, organic materials are most often described in the latest review articles [ 29 , 30 ], the subject of which concerns strategies implemented to improve the biogranulation process.…”