Biogas recirculation for simultaneous calcium removal and biogas purification within an expanded granular sludge bed system treating leachate

Comparison of Anaerobic Degradation Processes for Bioenergy Generation from Liquid Fraction of Pressed Solid Waste

“…Hence, this strategy may be equally useful for the management of LPW in the future. In another paper, Luo et al [31] produced biogas from leachate of solid municipal waste demonstrating highstrength organic pollutant content (41-59 g COD L -1 ) and good biodegradability (0.59-0.64 BOD COD -1 ), which are comparable with our LPW characteristics (111.6 g COD L -1 , 0.45 BOD COD -1 ). The measurements were conducted in continuous expanded granular sludge bed reactor at 35°C.…”

Biocatalysis conversion of methanol to methane in an upflow anaerobic sludge blanket (UASB) reactor: Long-term performance and inherent deficiencies

“…It is found that pH seriously influences the Ca-P precipitation (Manas et al, 2012); the effective Ca-P precipitation usually happens under alkaline condition (Wan et al, 2015). Likewise, for a noticeable calcite depositing, solution pH had better be higher than 8.0 (Luo et al, 2014). The pH inside the reactor, however, always kept below 7.5, which could have restricted the calcium precipitation.…”

Application of a CO2-stripping system for calcium removal to upgrade organic matter removal and sludge granulation in a leachate-fed EGSB bioreactor

“…Likewise, Kim et al 17 adopted biologically produced alkalinity in a UASB bioreactor to minimize the adverse effect of calcium hardness from industrial wastewaters with a respective process, and got a stable COD removal efficiency of over 90% aer some calcium was removed. In our previous work, 18 a scientic attempt on recirculating biogas (CO 2 ) from a leachate-fed EGSB bioreactor for the removal of calcium and simultaneous methane purication was also carried out; by optimizing the solution pH and imported biogas (CO 2 ), the calcium level suitable for microbial growth as well as and organic matter removal was achieved, which, as stated before, improved the sludge granulation and methane evolution to a large degree. However, the previous study mainly focused on the optimization of operational parameters (e.g.…”

“…The detailed schematic diagram of both reactors was shown in our previous research. 18 The reactors had a working effective volume of 6 L with an inside diameter of 8 cm and a height of 120 cm, and the granular sludge occupied 1/3 of the working volume of the EGSB bioreactor. A gas-liquid-solids separator was installed at the top of the reactors.…”

“…24 A CO 2 -stripping unit with biogas recirculation as a pretreatment effectively enhanced the removal of calcium from the leachate, with the resulting removal efficiency being up to 92.8-96.5%. 18 The noticeable decrease of calcium during the carbonation process resulted from its precipitation in the form of calcium carbonate in the presence of CO 2 from the biogas. In this sense, the methane content from reactor A varied between 41.5-57.9%.…”