Feasibility of treating emulsified oily and salty wastewaters through coagulation and bio-regenerated GAC filtration.

In the present study, chemical oxygen demand (COD) removal by coagulation and packed-columns of both fresh and bioregenerated granular activated carbon (GAC) is reported as a feasible treatment for saline and oily wastewaters (slops) generated from marine oil tankers cleaning. The use of Ferric chloride (FeCl3), Aluminium sulphate (Al2(SO4)3) and Polyaluminum chloride (Al2(OH3)Cl3) was evaluated in the pre-treatment by coagulation of a real slop, after a de-oiling phase in a tank skimmer Comparison of coagulation process indicated that Polyaluminum chloride and Aluminium sulphate operate equally well (20-30% of COD removal) when applied at their optimal dose (40 and 90 mg/l respectively) but the latter should be preferred in order to significantly control the sludge production. The results from the column filtration tests indicated the feasibility of using the selected GAC (Filtrasorb 400 -Calgon Carbon Corporation) to achieve the respect of the discharge limits in the slops treatment with a carbon usage rate in the range 0.1-0.3 kg/m3 of treated effluent. Moreover, biological regeneration through Alcalinovorax borkumensis SK2 was proved to be a cost-effective procedure since the reuse of spent GAC through such regeneration process for further treatment could still achieve approximately 90% of the initial sorption capacity, reducing then costs for the use of new sorbents and also the need for waste disposal.

Comparative Genome-Centric Analysis of Freshwater and Marine ANAMMOX Cultures Suggests Functional Redundancy in Nitrogen Removal Processes.

There is a lack of understanding of the interaction between anammox bacteria and the flanking microbial communities in both freshwater (non-saline) and marine (saline) ecosystems. Here, we present a comparative genome-based exploration of two different anammox bioreactors, through the analysis of 23 metagenome-assembled genomes (MAGs), 12 from freshwater anammox reactor (FWR), and 11 from marine anammox reactor (MWR). To understand the contribution of individual members to community functions, we applied the index of replication (iRep) to determine bacteria that are actively replicating. Using genomic content and iRep information, we provided a potential ecological role for the dominant members of the community based on the reactor operating conditions. In the non-saline system, anammox (Candidatus Brocadia sinica) and auxotrophic neighboring bacteria belonging to the phyla Ignavibacteriae and Chloroflexi might interact to reduce nitrate to nitrite for direct use by anammox bacteria. Whereas, in the saline reactor, anammox bacterium (Ca. Scalindua erythraensis) and flanking community belonging to phyla Planctomycetes (different than anammox bacteria)-which persistently growing in the system-may catabolize detritus and extracellular material and recycle nitrate to nitrite for direct use by anammox bacteria. Despite different microbial communities, there was functional redundancy in both ecosystems. These results signify the potential application of marine anammox bacteria for treating saline N-rich wastewaters.

Glutaraldehyde inhibits biological treatment of organic additives in hydraulic fracturing produced water.

Water generated by hydraulic fracturing for the production of oil and gas, commonly termed 'produced water', may contain residual organic compounds from the fracturing process or the subsurface formation. Biological treatment is a potential technology to remove residual organic compounds in produced water. Biocides are often added to both fracturing fluids and produced water to limit undesirable microbiological activity, and glutaraldehyde is the most commonly used biocide in hydraulic fracturing. Residual biocides in produced water can limit biological treatment efficiency. We evaluated the effect of glutaraldehyde on the biodegradation of five of the most commonly reported organic compounds in hydraulic fracturing fluids in an engineered biofilm treatment. Our results demonstrated that glutaraldehyde delays biological organic compound removal by introducing a biodegradation lag phase. In addition, the effects of glutaraldehyde were more pronounced for more rapidly degraded compounds. Finally, the presence of glutaraldehyde did not decrease microbial abundance nor drive microbial community structure, suggesting that observed effects were due to altered microbial activity. These results highlight the necessity to consider co-contaminant interactions during treatment of complex waste streams where residual biocide may be present.