Size-dependent calcium carbonate precipitation induced microbiologically in aerobic granules

Abstract

Calcium and ash accumulation in aerobic granules treating organic wastewater was investigated systematically in this study. It was found that ash content of granular sludge reached 43% at stable state of reactor operation with calcium carbonate precipitation as the main cause. Since granular sludge in the reactor at the steady state was the mixture of granules with different sizes, granules in the reactor on operation days 90, 120 and 150, respectively, were sorted into 10 categories by size to study the inorganic substances. It was found that calcium was selectively enriched in granules and the precipitation of calcium carbonate was just dependent on granule size instead of operation duration at the steady state. More calcium carbonate was precipitated in bigger aerobic granules, but both calcium and ash contents reached stable values when granule size was bigger than 700μm. Analysis by X-ray Diffractometer disclosed that aragonite was the only polymorph of calcium carbonate detected in aerobic granules with size bigger than 300μm. Scanning electron microscope revealed clearly for the first time that bundles of needle shaped aragonite was embedded in extracellular polymeric substances of aerobic granules. A mechanism on calcium carbonate precipitation was proposed to deepen the understanding of biomineralization.

Insights into the Current Trends in the Utilization of Bacteria for Microbially Induced Calcium Carbonate Precipitation

“…Liu et al . [146] studied the MICP of bacteria in activated sludge on aerobic granules of different sizes in the reactor for wastewater treatment. Local microenvironment varied due to different mass transfer resistance and thus affected the rate of MICP on granules with different sizes.…”

Understanding the Precipitated Calcium Carbonate (PCC) Production Mechanism and Its Characteristics in the Liquid-Gas System Using Milk of Lime (MOL) Suspension

“…They reported that the smallest solid to liquid ratio of 5 g L -1 resulted in maximum calcium extraction efficiency (73 %) while using 100 g L -1 produced the lowest extraction efficiency of 6 %. Liu et al 12 tested the performance of two organic acid (succinic and acetic acid) for the possible extraction of calcium from steel slag for PCC production. They reported that the carbonation of succinic acid leachate did not result in the production of PCC, whereas, the carbonation of acetic acid leachate resulted in the synthesis of PCC.…”

Mineralization Process of Biocemented Sand and Impact of Bacteria and Calcium Ions Concentrations on Crystal Morphology

“…600 . As a complex biological system, bacteria metabolism may provide the favourable microenvironments such as carbonate supersaturation for crystallization [25]. When [Ca 2+ ] = 0.25 mol/l and OD 600 = 0.25, the formed crystals have a rough surface and internal defects, and the single crystal phenomenon is more obvious ( Figures 11(A-1) and 11(B-1)).…”

“…Thus, it is easy to generate the ternary-level structure ( Figure 13). As a result, the interaction between organic and inorganic compounds and the charge density on the bacterial surface are the two key factors that affect the crystal morphology [25]. Lochhead et al [27] analysed the interaction between organic and inorganic compounds and found that [Ca 2+ ] is higher at the cell membrane interface than in the surrounding solution, regardless of the base [Ca 2+ ] value in the solution.…”