Optimization of linear alkylbenzene sulfonate (LAS) degradation in UASB reactors by varying bioavailability of LAS, hydraulic retention time and specific organic load rate

AbstractDegradation of linear alkylbenzene sulfonate (LAS) in UASB reactors was optimized by varying the bioavailability of LAS based on the concentration of biomass in the system (1.3–16gTS/L), the hydraulic retention time (HRT), which was operated at 6, 35 or 80h, and the concentration of co-substrates as specific organic loading rates (SOLR) ranging from 0.03–0.18gCOD/gTVS.d. The highest degradation rate of LAS (76%) was related to the lowest SOLR (0.03gCOD/gTVS.d). Variation of the HRT between 6 and 80h resulted in degradation rates of LAS ranging from 18% to 55%. Variation in the bioavailability of LAS resulted in discrete changes in the degradation rates (ranging from 37–53%). According to the DGGE profiles, the archaeal communities exhibited greater changes than the bacterial communities, especially in biomass samples that were obtained from the phase separator. The parameters that exhibited more influence on LAS degradation were the SOLR followed by the HRT

Anoxic microbial community robustness under variation of hydraulic retention time and availability of endogenous electron donors

The ADNMED (Anaerobic Digestion, Nitrification, and Mixotrophic Endogenous Denitrification) system comprises a triple chamber configuration that was shown to provide high-quality effluent regarding carbon, nitrogen, and sulfide. Hydraulic retention time (HRT) was 7 h in the anaerobic and anoxic chambers, and 5 h in the aerobic chamber (stage A). Sewage was directly added to the anoxic chamber to provide extra organic electron donors for denitrification (stage B) to improve the nitrogen removal efficiency (stage A 47 ± 19%). The addition of sewage at a flow rate equivalent to 10% of the feed flow increased nitrogen removal efficiency to 61 ± 12%. Illumina® sequencing revealed a restructuring of the microbial community in the anoxic chamber, according to the availability of the endogenous electron donors for denitrification. At stage A, denitrification was related to the decay of biomass, while the addition of sewage during stage B stimulated the establishment of fermentative bacteriaFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP2012/07375-7; 2009/15984-

Microbiome taxonomic and functional profiles of two domestic sewage treatment systems

Anaerobic systems for domestic sewage treatment, like septic tanks and anaerobic filters, are used in developing countries due to favorable economic and functional features. The anaerobic filter is used for the treatment of the septic tank effluent, to improve the COD removal efficiency of the system. The microbial composition and diversity of the microbiome from two wastewater treatment systems (factory and rural school) were compared through 16S rRNA gene sequencing using MiSeq 2 × 250 bp Illumina sequencing platform. Additionally, 16S rRNA data were used to predict the functional profile of the microbial communities using PICRUSt2. Results indicated that hydrogenotrophic methanogens, like Methanobacterium, were found in higher abundance in both systems compared to acetotrophic methanogens belonging to Methanosaeta genus. Also, important syntrophic microorganisms (Smithella, Syntrophus, Syntrophobacter) were found in the factory and rural school wastewater treatment systems. Microbial communities were also compared between stages (septic tank and anaerobic filter) of each wastewater treatment stage, revealing that, in the case of the rural school, both microbial communities were quite similar most likely due to hydraulic short-circuit issues. Meanwhile, in the factory, microbial communities from the septic tank and anaerobic filter were different. The school system showed lower COD removal rates (2–30%), which were probably related to a higher abundance of Firmicutes members in addition to the hydraulic short-circuit and low abundance of Chloroflexi members. On the other hand, the fiberglass factory presented higher COD removal rates (60–83%), harboring phyla reported as the core microbiome of anaerobic digesters (Bacteroidetes, Chloroflexi, and Proteobacteria phyla). The knowledge of the structure and composition of wastewater treatment systems may provide support for the improvement of the pollutant removal in anaerobic processCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ401720/2016-