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

Abstract

This study aimed to evaluate and compare the physical, chemical and biological properties of aerobic granular sludge from reactors with the addition of different powdered mineral materials. These properties have a significant impact on the efficiency of systems in which the biomass in granular form is used. Four identical granular sequencing batch reactors (GSBRs) were adopted for the research performed on a laboratory scale (R1—control reactor; R2, R3 and R4—with materials, PK, PG and PL respectively). The results indicate that the addition of powdered mineral materials improved the properties of biomass in reactors. The SVI5/SVI30 ratio values were significantly lower in the reactors with added materials (approx. 1.3 ± 0.3). The mean values of the sludge volume index at 30 min were the lowest in the R2 (39.8 ± 8.6 mL/g) and R4 (32.8 ± 10.7 mL/g) reactors. The settling velocity of biomass was the highest in the R2 reactor (15.4 ± 6.1 m/h). In the early days of the study, the highest extracellular polymeric substances (EPS) content was found in the biomass from the reactors to which the materials with higher Ca and Mg content were added (380.18–598.30 mg/g MLVSS). The rate of specific oxygen uptake (SOUR) by biomass indicated an insufficient biomass content in the R1 reactor—to 7.85 mg O2/(g MLVSS∙h)—while in the reactors with materials, the SOUR values were at the higher levels.

Powdered Ceramsite and Powdered Limestone Use in Aerobic Granular Sludge Technology

“…By contrast, Tao et al [ 26 ] reported that the SVI 30 values of two reactors (without or with GAC) did not obviously differ in or after the granulation phase. An extensive discussion of the results of own research with the literature data in this area is detailed in the publication by Czarnota et al [ 33 ].…”

“…After 89 days of GSBR operation, the mean sizes of the aggregates were 200.2, 783.1, and 430.0 µm in R1, R2, and R3, respectively ( Figure 4 a). The biogranulation process itself with the addition of these two materials, among others, is discussed in more detail in the article by Czarnota et al [ 33 ], which presents the impact of different powdered mineral materials on selected properties of aerobic granular sludge. Table 5 lists the average sizes of granules reported in previous studies of reactors in which powdered materials were applied.…”

“…The study used two powdered mineral materials, ceramsite (PK) and limestone (PL). Powdered ceramsite is a waste fraction from the production of ceramic aggregates, and its natural grain size ranges from 0.39 to 200 µm [ 11 , 15 , 33 ]. A powdered fraction of limestone was obtained by grinding a coarse material mechanically and then sieving it through a 0.2 mm sieve.…”

“…The first GSBR (R1—without powdered material) was a control reactor, whereas 3.0 g/L of PK or PL were added to reactors R2 and R3, respectively ( Figure 1 ). The construction of a single reactor used in the research has been presented in the article by Czarnota et al [ 33 ].…”

“…Additionally, the use of mineral and organic powdered materials can shorten the time required for activated sludge to granulate because they act as nuclei that induce the aggregation of microorganisms [ 25 ]. Furthermore, divalent cations (i.e., Ca 2+ , Mg 2+ ) in the mineral materials may participate in the formation of aggregate matrices [ 32 , 33 ].…”