Suchergebnisse

In different regions of the world as well as in many parts of Brazil, high percentage of thepopulation and sometimes, entire isolated communities do not have access to seweragesystem or sewage treatment. The common scenario is the use of septic tanks and, in manycases, direct discharge into water bodies. The objective of this study was to develop and test alow-cost sewage treatment system, appropriate for isolated or poor communities at the sametime, meeting the discharge threshold limits established by the Brazilian regulation. For that, acompact engineering ecosystem for decentralized treatment of domestic sewage wasconstructed and tested in a research unit installed in an environmental protected area inGrande Island, south coast of Rio de Janeiro State. The system is formed by septic tank,submersed aerated filter, secondary decanter, and for polishing, vegetated tanks containingaquatic macrophytes (wetland) and one tank with algae. The results of a 200 day monitoringperiod, covering two different flows rates (200 L.h-1 and 52 L.h-1) are presented. With thelower flow (52 L.h-1), the following removal efficiency was achieved: 87.8% (nitrite); 71%(nitrate); 47% (Ammoniacal nitrogen); 89% (COD); 40.2% (total phosphorus). After the flowreduction, most of parameters analysed, met the threshold limits established by the BrazilianFederal Legislation, which demonstrated that the system fulfilled its purpose. ; In different regions of the world as well as in many parts of Brazil, high percentage of thepopulation and sometimes, entire isolated communities do not have access to seweragesystem or sewage treatment. The common scenario is the use of septic tanks and, in manycases, direct discharge into water bodies. The objective of this study was to develop and test alow-cost sewage treatment system, appropriate for isolated or poor communities at the sametime, meeting the discharge threshold limits established by the Brazilian regulation. For that, acompact engineering ecosystem for decentralized treatment of domestic sewage wasconstructed and tested in a research unit installed in an environmental protected area inGrande Island, south coast of Rio de Janeiro State. The system is formed by septic tank,submersed aerated filter, secondary decanter, and for polishing, vegetated tanks containingaquatic macrophytes (wetland) and one tank with algae. The results of a 200 day monitoringperiod, covering two different flows rates (200 L.h-1 and 52 L.h-1) are presented. With thelower flow (52 L.h-1), the following removal efficiency was achieved: 87.8% (nitrite); 71%(nitrate); 47% (Ammoniacal nitrogen); 89% (COD); 40.2% (total phosphorus). After the flowreduction, most of parameters analysed, met the threshold limits established by the BrazilianFederal Legislation, which demonstrated that the system fulfilled its purpose.

ABSTRACTThe capacity of the sewage‐treatment works at Silchester in Hampshire has been enhanced and the effluent quality improved to a high standard by the installation of a new submerged biological aerated filter plant. Ten prefabricated steel submerged aerated filters reduce BOD and fully nitrify settled domestic sewage from a population equivalent of 20 000.Comprehensive operating data are presented to demonstrate the ability of single‐stage submerged downflow aerated biological filters to produce a nitrified effluent. The final effluent quality remains consistently within consent limits at 4.8 mg/l BOD, 7.0 mg/l SS and 0.5 mg/l NH3‐N, all 95 percentiles. (Consent 7 mg/l BOD, 25 mg/l SS, and 5 mg/l NH3‐N, 95 percentiles.)Data are presented on total coliform and E. Coli concentrations through the filter plant, showing better than 3 log reductions in the effluent.

AbstractThe established procedures for quantifying the aeration capacity of diffusers used in submerged aerated filter wastewater‐treatment systems do not consider the effects of support media; this may lead to ineffective design and sizing of diffused‐air systems. The study was carried out to determine the factors affecting aeration in a submerged aerated filter containing high‐voidage random‐packed plastic media. Tests were conducted in a full‐scale model reactor with and without support media.

AbstractThis work aimed to assess the technical and energetic feasibility of a passively aerated laboratory‐scale trickling filter, configured as a two‐stage system, to produce urban wastewater (UWW) reusable in agriculture. The trickling filter was fed continuously with high‐strength UWW at four hydraulic retention times (HRTs), that is, 10, 5, 2 and 1 day, corresponding to organic loading rates (OLRs) of 0.1, 0.2, 0.5 and 0.9 kg COD/m3/d, respectively. The results revealed a good performance in organic load removal and nitrification at the four HRTs. The trickling filter showed high organic pollutant removal efficiencies of up to 93%, 94% and 98% for chemical oxygen demand (COD), BOD5 and total suspended solid (TSS), respectively, as well as high ammonia nitrogen removal above 96% at the shortest HRT of 1 day. All physicochemical parameters were significantly lower than the allowable limits set out in ISO 16075 for category C (non‐food crop irrigation) irrigation water. The reuse of treated UWW in irrigation led to germination indexes and growth parameters of triticale (Triticosecale Wittm.) almost equal to those obtained using tap water. Energy use was found to be about 0.2754 kWh/m3 of treated wastewater, making it competitive with trickling filter plants reported in the literature. The simplicity and energy efficiency of the developed trickling filter system, combined with its capacity for almost full nitrification, make it appealing for sewage treatment in small communities in developing countries.

ABSTRACTBiological aerated filters are wastewater‐treatment systems which contain support media for the development of a biofilm and provide oxygen at the base of the reactor for aerobic microbial processes. The origins of this type of filter date back to the early 1900s, and modern designs can provide a high level of treatment in small reactor 'footprints'.This paper provides a review of the technology and development of biological aerated filters and submerged aerated filter systems.

ABSTRACTBiological filters with fixed submerged beds are normally used for secondary or tertiary treatment and are recognized for their good performance. These processes are designed to meet, simultaneously, strict requirements of quality and operation. The achievement of the discharge consent requires the use of fine media which features a large support surface for the growth of biomass. On the other hand, the achievement of long filter run times is intrinsically related to the use of coarse media. Nowadays, all biological filters have mono‐media, which offers a compromise between these two conflicting criteria.The B2A process is a newly developed compact filter which ensures high filtration performance and long filter run times, even when used for crude sewage. The technology has been in use since 1992 for nitrification/ denitrification using an applied load of 0.7 kg/m3. d to obtain an effluent quality of 20 mg/l total nitrogen. Further tests have proved its efficiency in the removal of carbonaceous pollution.The B2A process is the first compact filter capable of treating screened crude sewage yet producing effluent qualities which are equal to that from conventional biological filters receiving settled sewage.

AbstractSimultaneous removal of carbon, nitrogen and phosphorus from hypersaline wastewater by halophiles bioaugmented intermittently aerated biological filter (IABF) was systematically investigated in this research. The bioaugmented IABF showed significantly improved simultaneous nutrient removal efficiency in salinity range of 6–11% compared to the uninoculated IABF although the benefit of inoculation was no more evident with further increase in salinity. As high as 12% difference in COD removal efficiency, 18% difference in TN removal efficiency and 14.6% difference in TP removal efficiency were observed between the inoculated and uninoculated IABF. Reactor performance was negatively affected by backwashing at hypersaline conditions. However, inoculation of halophiles reduced the biofilm recovery time after backwashing. Growth curve of halophiles, as well as biomass loading and dehydrogenase activity, at different salinities were studied to explore the bioaugmentation mechanism. Excellent correlation was observed between the halophile growth curve, biomass loading and DHA and the removal efficiency of the organic pollutant, which can be used to predict the biofilter performance in removing the organic matters through the analysis of halophiles growth curve, biomass loading and DHA in the reactor.