Wastewater treatment should not only be concerned with urban hygiene and environmental protection, but development of a sustainable society must also be considered. This implies a minimisation of the energy demand and potential recovery of finite minerals. Urine contains 80% of the nitrogen (N) and 45% of the phosphorus (P) in wastewater. Separate collection and treatment would improve effluent quality and save energy in centralised biological nutrient removal (BNR). BNR processes are not optimal to treat water with very low N concentration resulting from separate urine collection. Relying on nutrient removal through sludge production, methanation of the sludge, subsequent nutrient removal from the digestion effluent results in optimised and more sustainable wastewater treatment. This paper quantitatively evaluates this option and discusses the potential.
Marine fungi are known to originate from a wide variety of habitats within the marine environment. Marine sediment represents one environmental niche, with most fungi occurring in these sediments being facultative marine fungi with terrestrial origins. It has not been proven whether these fungi merely survive the harsh environmental conditions presented by the ocean sediment, as opposed to playing an active role in this ecological niche. During this study, marine sediment was collected from St. Helena Bay, on the west coast of the Western Cape, South Africa. Using dilution, enrichment, and repetitive culturing techniques, 59 fungal isolates were obtained from marine sediments and identified to at least genus level using morphological and molecular methods. Moreover, a series of tests were performed to characterize the physical and physicochemical attributes of the isolates. Results showed that the isolates not only survived but also had the potential to grow in the natural conditions present in this environment. Extracellular cellulase was produced by the filamentous fungal isolates indicating their probable role in detrital decay processes and therefore the carbon cycle on the ocean bed. Also, denitrification patterns were observed when isolates were grown in liquid media amended with NaNO(2), NaNO(3), and (NH(4))SO(4), implicating that these fungi have the potential to play an active role in denitrification, co-denitrification, and ammonification phases of nitrogen cycles occurring in the marine sediments.
Municipal wastewater contains a mixture of minerals from different origins. Urine contributes 80% of the nitrogen (N) and 45% of the phosphate (P) load in wastewater. Effects of separate urine collection on BNR processes were evaluated by using a simulation model for an existing stateof-the-art biological nutrient removal process. It was found that increasing urine separation efficiency leads to lower nitrate effluent concentrations, while ammonium and phosphorus concentrations remain more or less the same. The improved nitrate effluent quality is most notable up to 50-60% urine separation. Urine separation allows primary sedimentation without an increase in the nitrate effluent concentration. Furthermore, urine separation increases the potential treatment capacity for raw and settled wastewater by 20% and 60%, respectively. Urine separation provides options for increasing the lifetime of existing treatment works.
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