AI Article Synopsis
- Cheese whey (CW) is a nutrient-poor dairy waste that requires added nutrients for effective aerobic treatment, which can be achieved using an algal-bacterial granular system in a sequencing batch reactor (SBR).
- This study revealed that the algal-bacterial SBR effectively removed 100% of chemical oxygen demand (COD) and 94% of ammonia, while also reducing CO emissions by about 20%.
- Compared to bacterial-only systems, the algal-bacterial system demonstrated improved nitrogen management with lower nitrification and denitrification losses, allowing for higher biomass production that could potentially be used for generating valuable products.
Article Abstract
Cheese whey (CW) is a nutrient deficient dairy effluent, which requires external nutrient supplementation for aerobic treatment. CW, supplemented with ammonia, can be treated using aerobic granular sludge (AGS) in a sequencing batch reactor (SBR). AGS are aggregates of microbial origin that do not coagulate under reduced hydrodynamic shear and settle significantly faster than activated sludge flocs. However, granular instability, slow granulation start-up, high energy consumption and CO emission have been reported as the main limitations in bacterial AGS-SBR. Algal-bacterial granular systems have shown be an innovative alternative to improve these limitations. Unfortunately, algal-bacterial granular systems for the treatment of wastewaters with higher organic loads such as CW have been poorly studied. In this study, an algal-bacterial granular system implemented in a SBR (SBR) for the aerobic treatment of ammonia-supplemented CW wastewaters was investigated and compared with a bacterial granular reactor (SBR). Mass balances were used to estimate carbon and nitrogen (N) assimilation, nitrification and denitrification in both set-ups. SBR exhibited COD and ammonia removal of 100% and 94% respectively, high nitrification (89%) and simultaneous nitrification-denitrification (SND) of 23% leading to an inorganic N removal of 30%. The efficient algal-bacterial symbiosis in granular systems completely removed COD and ammonia (100%) present in the dairy wastewater. SBR microalgae growth could reduce about 20% of the CO emissions produced by bacterial oxidation of organic compounds according to estimates based on synthesis reactions of bacterial and algal biomass, in which the amount of assimilated N determined by mass balance was taken into account. A lower nitrification (75%) and minor loss of N by denitrifying activity (<5% Ng, SND 2%) was also encountered in SBR as a result of its higher biomass production, which could be used for the generation of value-added products such as biofertilizers and biostimulants.
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| http://dx.doi.org/10.1016/j.chemosphere.2024.141250 | DOI Listing |
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