Combining submerged membrane technology with anaerobic and ...
Combining submerged membrane technology with anaerobic and ...
Combining submerged membrane technology with anaerobic and ...
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ConclusionsThe main conclusions of this research, which is focused on the combination of<strong>submerged</strong> <strong>membrane</strong> <strong>technology</strong> <strong>with</strong> <strong>anaerobic</strong> <strong>and</strong> aerobic biological treatments, arenow presented.1. Submerged <strong>membrane</strong>s in tertiary <strong>membrane</strong> filtration systemsFrom the results obtained it can be conclude that <strong>submerged</strong> <strong>membrane</strong> <strong>technology</strong>is a good choice in order to obtain an effluent <strong>with</strong> a high quality <strong>and</strong> free of suspendedsolids after a biological treatment in sequencing batch reactors <strong>with</strong> granular <strong>and</strong> flocculentbiomass. The operation of the tertiary filtration units <strong>with</strong> a higher biomass concentrationthat that typically recommended for this kind of systems made them to behave assecondary bioreactors, eliminating part of the COD <strong>and</strong> nitrifying the ammoniumproceeding from the reactors. The negative effect was the lower <strong>membrane</strong> fluxesachieved. Finally, the aggregation state of the biomass did not make any difference in theoperation of the tertiary filtration systems <strong>and</strong> other parameters such as nitrification or thepresence of suspended solids in the raw wastewater showed a more relevant impact in<strong>membrane</strong> performance.2. Membrane bioreactor combined <strong>with</strong> UASB reactorThe combination of an aerobic MBR <strong>with</strong> an <strong>anaerobic</strong> UASB reactor, into one singleintegrated system or as post-treatment, was shown to be a good solution for the treatmentof low-strength wastewaters at ambient temperature, producing a high quality effluent,producing biogas rich <strong>with</strong> methane <strong>and</strong> diminishing sludge production yield. Moreover, thecombined system showed flexibility to convert total nitrogen to ammonia <strong>and</strong>/or nitrate,<strong>with</strong> is really interesting for its use in water reuse depending on the application <strong>and</strong> qualityst<strong>and</strong>ards. The hydrolysis of suspended biomass recirculated from the MBR to the UASBprovoked the release of biopolymeric substances that worsened <strong>membrane</strong> performance.Therefore, it would be interesting to develop strategies in order to remove the colloidalmatter resulting from the <strong>anaerobic</strong> digestion of complex substrates. In this sense, the useof a stage <strong>with</strong> superior organisms such as protozoa could be an interesting alternative.The presence of plastic support during this study promoted the presence of protozoa <strong>and</strong>influenced colloidal biopolymer concentration.205
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