Two of the challenges facing Africa in the 21st Century are effective use of restricted water resources and ensuring food security especially for poor communities. In line with these aims, the eThekwini municipality has introduced a multi-tier system of water supply ranging from full pressure reticulated systems along with flush toilets to standpipes and dry toilet systems. In the latter case, it was soon recognized that the disposal of greywater presented a problem. Bearing in mind that South Africa is already a water scarce region, research was initiated into finding means of using this water as a resource rather than as a waste. Initial on-site trials using the greywater to irrigate crops proved popular and it was then regarded as necessary to test the possible health effects on the communities of such a system. A controlled field trial using pot plantings of a selected range of edible vegetables was initiated at the University of KwaZulu-Natal. Crops were tested both internally and externally for a range of indicator and potentially pathogenic organisms. Quantitative Microbial Risk Assessment (QMRA) techniques were used to assess the health risk to communities from growing and eating the greywater- irrigated vegetables. Although there was a health risk related to most of the activities, especially the handling of the greywater itself, the risks could be brought within the World Health Organisation guidelines of less than one case of disease per 10 000 people per year by the implementation of simple barrier interventions. The greywater irrigated crops themselves, did not present a statistically higher risk of infection than the crops irrigated with either hydroponic solution or tap water. These findings show the importance of applying QMRA to each case to determine health risk. This would allow the productive use of greywater and other water sources in the correct circumstances, thus providing food sustainability for people who currently do not have access to the levels of high purity water currently recommended for agriculture. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.

Universidade Federal do Cearà / Para a detecÃÃo de Aeromonas foram coletadas 90 amostras de Ãgua de superficie e 30 de peixes no estuÃrio do rio Bacanga em SÃo LuÃs/MA, no perÃodo de marÃo a outubro de 2004. As amostras foram submetidas, simultaneamente, ao mÃtodo de plaqueamento direto em Agar Gelatina Fosfato Sal (Agar GSP acrescido de 20flglrnL de ampicilina) para a contagem (UFC/rnL ou g) e a determinaÃÃo do NÃmero Mais ProvÃvel (NMP/100rnL ou g) pela tÃcnica dos tubos mÃltiplos, utilizando-se o Caldo Tripticase Soja (Caldo TSB com 20flglrnL de ampicilina). As espÃcies de peixes analisadas foram: Bagre (Pimelodus maculatus), Tainha (Mugil cephalus), Solha (Pleuronectes platessa), Prata (Hemigrammus rodwayi), Sardinha (Opisthonema oglinum). Os resultados obtidos retratam uma ampla disseminaÃÃo de Aeromonas no estuÃrio. Para as amostras de Ãgua e peixes as contagens variaram de 40 a 1,3x108 UFC/rnL e de 3,2x102 a 5,8x106 UFC/g respectivamente, sendo que os maiores Ãndices foram obtidos nos pontos prÃximos Ãs emissÃes de esgotos domÃsticos. Os valores para o NMP/lOOrnL de Ãgua oscilaram entre 2,3x104 e 1,6x107 e de 230 a 24000/g para peixe. Os maiores Ãndices de Aeromonas foram constatados no mÃs de maior intensidade de chuvas, abril, e os menores em outubro, correspondente ao pico de estiagem na regiÃo, evidenciando assim uma possÃvel sazonal idade na incidÃncia da bactÃria no ambiente estudado. Das 751 cepas isoladas das amostras de Ãgua, 582 foram positivas para Aeromonas, sendo que 52,70. 10 eramA. caviae, 23,8% A. hydrophila, 19,5%,A. veronii e 3,7%A. sobria. Para as isoladas do pescado (245 cepas) 184 foram identificadas como Aeromonas sendo 43,4% de A. caviae, 28,2% de A. hydrophila, 26,6% A. veronii e 1,6% de A. sobria. Com relaÃÃo aos parÃmetros fisico-quÃmicos medidos nas Ãguas de superficie do estuÃrio do rio Bacanga, apenas a temperatura, a salinidade e o pH, tiveram correlaÃÃes significativas. De modo geral, as cepas de Aeromonas sp. foram sensÃveis a maioria dos antimicrobianos testados, com exceÃÃo de ampicilina, ao qual 100% das cepas foram resistentes. / For the detection of Aeromonas were collected 90 samples of surface water and 30 fish in the estuary of the river in St. Louis Bacanga / MA in the period March to October 2004. The samples were submitted, while the method of direct plating on Gelatin Phosphate Salt Agar (Agar GSP plus 20flglrnL of ampicillin) to count (CFU / g or RNL) and the determination of Most Probable Number (NMP/100rnL or g) by the multiple tube technique, using trypticase soya broth (TSB broth with ampicillin to 20flglrnL). The fish species examined were: Bagre (Pimelodus maculatus), Mullet (Mugil cephalus), plaice (Pleuronectes platessa), Silver (Hemigrammus Rodway), Sardines (Opisthonema oglinum). The results show a wide spread of Aeromonas in the estuary. For samples of water and the fish counts ranged from 40 to 1.3 x108 CFU / NLOs and 3.2 x102 to 5.8 x106 CFU / g respectively, and the highest rates were obtained at points close to the emission of domestic sewage. The values for the NMP / lOOrnL of water ranged from 2.3 x104 and 1.6 x107 and 230 to 24,000 / g for fish. The highest rates of Aeromonas were observed in the month of highest intensity of rainfall, April, and lowest in October, corresponding to the peak of drought in the region, thus a possible seasonal effect in the age of the bacteria in the environment studied. Of the 751 strains isolated from water samples, 582 were positive for Aeromonas, with 52.70. 10 were. caviae, 23.8% A. hydrophila, 19.5%, A. A. veronii and 3.7% sobria. For the isolated fish (245 strains) 184 were identified as Aeromonas and 43.4% of A. caviae, 28.2% of A. hydrophila, 26.6% A. veronii and 1.6% of A. sobria. Regarding the physico-chemical parameters measured in surface waters of the estuary of the river Bacanga, only the temperature, salinity and pH, had significant correlations. In general, the strains of Aeromonas sp. were sensitive to most antimicrobials tested, except ampicillin, to which 100% of strains were resistant.

The existing linear economy approach to nutrient management has clear shortcomings including high expenditures for nutrient extraction and production of fertilizer as well as additional costs for nutrient removal at downstream waste water treatment plants (WWTPs) to prevent the pollution of aquatic environments. In a circular nutrient economy, phosphorus (P) and nitrogen (N) are removed from waste streams and captured as valuable fertilizer products in order to more sustainably reuse the resources in closed-loops and simultaneously protect receiving aquatic environments from harmful P and N emissions. The overarching aim of this thesis is to understand strategic approaches for nutrient recovery from wastewater and advance membrane technologies for P and N reclamation. The studies i.) approach nutrient recovery on a system-level to recognize optimal waste streams to target for P and N separation, ii.) advance membrane-based processes for nutrient recovery, and iii.) examine the economic viability of the nutrient recovery techniques.The thesis presents a thermodynamic and energy analysis of nutrient recovery from various waste streams of fresh and hydrolyzed urine, greywater, domestic wastewater, and secondary treated wastewater effluent. The analysis revealed comparative advantages in theoretical energy intensities for P and N recovery from nutrient-dense waste streams, such as fresh and hydrolyzed urine, compared to other more dilute sources. The thesis quantifies efficiencies required by separation techniques for nutrient reclamation to be competitive with the energy requirements of the prevailing industrial fertilizer production methods, i.e., phosphate mining and nitrogen fixation by the Haber-Bosch process. The dissertation examines and advances the performance of membrane-based processes for separation and recovery of P and N from diverted human urine. Donnan dialysis (DD), an ion-exchange membrane-based process, can capture and enrich orthophosphate, HxPO4(3−x)−, from source-separated urine. This work demonstrates the transport of Cl− driver ions down a concentration gradient, across an ion-exchange membrane to set up an electrochemical potential gradient that drives the transport of target HxPO4(3−x)− in the opposite direction, enabling P capture. Importantly, H2PO4− is transported against an orthophosphate concentration gradient, which achieves uphill transport of P. The thesis also provides a framework to better understand the impact of different ions in the water matrix on P recovery potential and kinetics. The thesis presents a novel operation of membrane distillation (MD) — isothermal membrane distillation with acidic collector (IMD-AC) — to selectively recover volatile ammonia, NH3, from hydrolyzed urine. The innovative isothermal and acidic collector features, respectively, suppressed undesired water permeation and enhanced ammonia vapor flux relative to conventional membrane distillation (CMD). The elimination of water flux in IMD-AC resulted in ≈95% savings in vaporization energy consumption relative to CMD. Critically, IMD-AC achieved uphill transport of ammoniacal nitrogen, i.e., transport against a concentration gradient, demonstrating the promising potential of the technique for N recovery. The dissertation proposes an integrated bipolar membrane electrodialysis (BPM-ED), DD, and IMD-AC system to drive the separation and recovery of orthophosphate and ammoniacal nitrogen from human urine. This work elucidates the role of pH and nutrient speciation (i.e., H2PO4− versus HPO42− and NH4+ versus NH3) on the performance of DD and IMD-AC. In the proposed configuration, BPM-ED generates acids and bases in situ to strategically control the pH of urine streams to benefit DD and IMD-AC performances. Strategic pH modification can enhance orthophosphate transport and selectivity in DD as well as ammonia transport and recovery potential in IMD-AC. Importantly, the analysis quantifies comparable specific energy consumptions of the proposed integrated membrane-based process to the existing approaches to P and N management. This thesis presents a preliminary economic assessment of onsite nutrient recovery employing DD and IMD-AC for respective P and N recovery from diverted urine. The analysis reveals opportunities to utilize widely-available waste chemical streams and recovered thermal energy to improve the economic viability of nutrient recovery. The largest capital expenditures are urine diversion toilets and additional piping for source-separation. Preliminary analysis demonstrates that employing urine diversion in public sanitation rooms, as opposed to private bathrooms, can reduce these capital expenditures. Furthermore, realizing savings from avoided costs for downstream nutrient removal at centralized wastewater treatment plants in addition to fertilizer revenue can enhance the economic viability of the approach. Overall, this dissertation critically informs nutrient recovery approaches and advances membrane-based processes for P and N reclamation to facilitate a paradigm shift from an inefficient linear nutrient economy to a sustainable circular nutrient economy. The work reveals opportunities to minimize energy intensity for nutrient separation, advance the performance of membrane-based techniques for selective and energy-efficient nutrient recovery from urine, and enhance the cost-competitiveness of nutrient reclamation. The findings of this work support nutrient recovery efforts and provide important insights that can be applied to other separation and resource recovery endeavors.

<p> The effect of low temperature on the physico-chemical treatment (PCT) of domestic wastewater is examined with special emphasis placed on activated carbon adsorption. PCT is a recent processing scheme, wherein wastewater goes through sedimentation, precipitation, deep bed filtration and adsorption. In PCT, activated carbon adsorption takes the place of conventional biological treatment for organic removal.</p> <p> Both batch studies using powdered activated carbon (PAC) and continuous flow studies with granular activated carbon (GAC) on a pure compound, sodium dodecyl sulfate (SDS) and domestic wastewater from the Dundas, Ontario Water Pollution Control Plant were investigated.</p> <p> Theoretical analysis and batch feasibility studies indicate that the effect of low temperature on coagulation, flocculation and sedimentation were quite easily handled within established design parameters. Batch studies on PAC treatment show that the carbon floc is easily separable from wastewater with the aid of a small dosage of polyelectrolyte and high effluent quality is obtainable at temperatures ranging from 2° - 25°C.</p> <p> Granular activated carbon was evaluated first on a pure compound, SDS. Batch isotherms and kinetics were also conducted at the same time to determine parameters needed for continuous flow modelling. Results derived from this phase of the study indicate that the activation energy from column studies is quite low (approximately 3.0 kcal/mole). Close match is obtained between the theoretical model (a modification of Thomas' reaction kinetics) and experimental data.</p> <p> Finally PCT pilot plant studies on domestic wastewater were carried out, at 5°C and 25°C. Soluble organic carbon removal was in excess of that predicted by purely adsorption type phenomenon. This is attributed to microbial activity inside the carbon columns. Greater soluble organic removal was seen at 25°C than at 5°C. Denitrification inside the carbon columns was found to be quite significant, again with stronger denitrifying activity at 25°C than at 5°C. Microbiological investigation of the carbon from the exhausted columns revealed over 10^9 cells/cm^3) of GAC bed volume from the lead column at 25°C. Denitrifiers were also detected in the carbon. Iodine numbers were determined on used carbon, which indicated the exhaustion of activated carbon capacity. Organic removal, however, continued undiminished, due to bacterial activity.</p> <p> The study culminated with the development of a theoretical model incorporating bacterial activity. The results of column effluent profile, however, indicated great discrepancy between theoretical predictions and experimental observations. This was attributed to simplistic assumptions utilized in solving the fixed bed problem.</p> / Thesis / Master of Engineering (MEngr)

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-05-14T19:03:21Z No. of bitstreams: 1 ELIANA PEREIRA DE SOUSA - DISSERTAÇÃO PPGSA PROFISSIONAL 2015..pdf: 1692020 bytes, checksum: 07e521abb68031a2118412065788e72e (MD5) / Made available in DSpace on 2018-05-14T19:03:21Z (GMT). No. of bitstreams: 1 ELIANA PEREIRA DE SOUSA - DISSERTAÇÃO PPGSA PROFISSIONAL 2015..pdf: 1692020 bytes, checksum: 07e521abb68031a2118412065788e72e (MD5) Previous issue date: 2015 / A presente pesquisa investigou o desempenho do pós-tratamento de efluente de tanque séptico em filtros de areia de fluxos intermitentes, visando obter um esgoto tratado com qualidade adequada para reuso na irrigação. O esgoto doméstico foi proveniente do bloco de aulas II do Centro de Ciências e Tecnologia Agroalimentar (CCTA), da Universidade Federal de Campina Grande (UFCG). O controle de entrada do fluxo no sistema também foi quantificado. O sistema experimental foi constituído de um tanque séptico, três filtros de areia com fluxo intermitente e uma caixa de armazenamento. Os três filtros aeróbios de areia foram preenchidos com brita e areia na seguinte proporção: 10 cm de brita nº 1 na base, 50 cm de areia na porção mediana e 5 cm de brita nº 0 na porção superior. A areia utilizada nos três filtros foi a mesma, sendo peneirada numa peneira com diâmetro de 0,50 mm. O primeiro filtro recebeu 200 L/dia (50 L a cada 6hs) de efluente do tanque séptico, o segundo filtro recebeu 150 L/dia (50 L a cada 8hs) e o terceiro filtro recebeu 100 L/dia (50 L a cada 12hs). Realizaram-se campanhas de medição, no período de Novembro/2014 a Fevereiro/2015 para caracterizar os efluentes nos aspectos físico-químicos e microbiológicos como indicadores de transformação da qualidade da água. Os parâmetros analisados foram: OD, temperatura, turbidez, pH, CE, cor, dureza total, Ca, Mg, cloretos, N, Na, K, P, DQO, DBO5, CT, CTT e E.coli. A análise de variância (ANOVA) foi realizada para comparar as concentrações de todos os parâmetros entre os efluentes, com nível de significância de 5%. Temperatura, turbidez, CE, cor, dureza total, Ca, Mg, cloretos, Na, K, P, DQO, DBO5, CT, CTT e E.coli não apresentaram diferenças estatísticas significantes. O OD apresentou significância. O N, muita significância e o pH, extrema significância estatística. Os filtros reduziram as concentrações de nutrientes, matéria orgânica e microorganismos patógenos, porém, com os reduzidos tempos de intermitências adotados não foi possível encontrar diferenças estatísticas entre os tratamentos. Os valores encontrados não foram compatíveis com os recomendados para uso na agricultura, segundo a Resolução do CONAMA. / This research investigated the performance of the post-treatment of septic tank effluent sand filters intermittent flows, to obtain a treaty with sewage quality suitable for reuse in irrigation. The sewage was coming from the classes of block II of the Center for Science and Technology Agrifood (CCTA), the Federal University of Campina Grande (UFCG). The input flow control in the system was also quantified. The experimental system was composed of a septic tank of three sand filters with intermittent flow and a storage box. The three aerobic sand filters were filled with gravel and sand at the following ratio: 10 cm crushed base # 1, 50 cm in the middle portion sand and crushed stone No. 5 0 cm in the upper portion. The sand used in the three filters was the same, being sieved through a sieve with a diameter of 0.50 mm. The first filter received 200 L / day (50 L each 6am) of effluent from septic tank, the second filter received 150 L / day (50 L every 8h) filter and the third received 100 L / day (50 L each 12pm). There were measurement campaigns, from November / 2014 to February / 2015 to characterize the effluents in the physical, chemical and microbiological aspects as processing indicators of water quality. The parameters analyzed were: OD, temperature, turbidity, pH, EC, color, total hardness, Ca, Mg, chlorides, N, Na, K, P, COD, BOD 5, CT, CTT and E. coli. The analysis of variance (ANOVA) was performed to compare the concentrations of all the parameters in the effluent, at 5% significance level. Temperature, turbidity, EC, color, total hardness, Ca, Mg, chlorides, Na, K, P, COD, BOD 5, CT, CTT and E. coli showed no statistically significant differences. The OD showed significant. The N, much significance and the pH, extreme statistical significance. The filters reduced the concentrations of nutrients, organic matter and pathogenic microorganisms, but with reduced flickers adopted times could not find statistical differences between treatments. These values were not compatible with those recommended for agricultural use, according to CONAMA resolution.

O pós-tratamento apresenta-se como uma forma de adequar o efluente de reatores anaeróbios aos requisitos da legislação ambiental e propiciar a proteção dos corpos receptores. O trabalho foi desenvolvido com a finalidade de avaliar a viabilidade técnica da utilização do processo de ozonização quando aplicado a um sistema combinado composto por reator UASB seguido por biofiltro aerado submerso. No sistema foi avaliada a operação de quatro biofiltros, dois com carvão ativado e dois com anéis de polietileno. Para verificar a influência da oxidação com ozônio na biodegrabilidade somente um dos biofiltros preenchidos por cada material suporte recebeu efluente ozonizado. Os menores valores de concentração de DQO foram encontrados nos filtros preenchidos com carvão ativado granular, com valores de até 14,00 mg/L, para os dois tipos de afluentes, ozonizado e não-ozonizado. Contudo, considerando eficiência de remoção de DQO para todo período de operação os biofiltros preenchidos com anéis de polietileno se mostraram mais eficazes, com eficiência de até 80%. Os resultados evidenciaram a ocorrência de nitrificação em todos os sistemas, uma vez que houve consumo de NTK e de alcalinidade, com queda de pH; produção de nitrato. / The post-treatment is presented as an alternative to adjust the effluent of anaerobic reactors to the requirements of the brazilian environmental legislation. The work was developed with the purpose to evaluate the viability of the use of the ozonization process when applied to a system composed by a reactor UASB followed by submerged aerated biofilter. In the system the operation of four biofilters was evaluated, two fillet with granular activated carbon (GAC) and two with polyethylene rings. To check the influence of the oxidation with ozone in biodegradability, only one of the biofilter with each support material received ozonized effluent. The lowest values of DQO concentration had been found in the filters with GAC, with values of up to 14,00 mg/L, for the two types, ozonized and not-ozonized. However, considering the DQO removal efficiency for all operation periods the biofilters with polyethylene rings were more efficient, with efficiency of up to 80%. The results had evidenced the occurrence of nitrification in all the systems, a time that had NTK and alkalinity consumption, with fall of pH and nitrate production.

Microalgas são interessantes fontes de lipídeos para produção de biodiesel. No entanto, seus cultivos para tal finalidade são apenas viáveis do ponto de vista ambiental e econômico se apresentarem elevadas produtividades de biomassa e de lipídeos e estiverem associados ao uso de efluentes. A presente pesquisa estudou as condições de cultivo das microalgas Desmodesmus e Scenedesmus, considerando o conteúdo lipídico para produção de biodiesel, aliado à análise da eficiência de remoção de nutrientes pelas cepas, além da avaliação do efluente de reator UASB (esgoto sanitário) como meio alternativo ao cultivo. Dentre 22 cepas de microalgas isoladas de ambientes de água doce e lagoas de estabilização, 2 foram selecionadas para otimização de seus cultivos diante das suas capacidades de acumularem lipídeos e crescerem em diferentes condições físico-químicas. Delineamento Composto Central Rotacional (DCCR) foi aplicado para otimização das condições de crescimento celular das cepas LE17 (34,5ºC, pH 8,2 e 200 &#956mol.m-2.s-1) e ITU07 (34ºC, pH 8,2 e 180 &#956mol.m-2.s-1). Definidas as condições ótimas, foram realizados os cultivos mixotróficos das cepas em batelada (8 litros) em meio sintético e em efluente de reator UASB (50%). Nos cultivos em efluente de reator UASB as produtividades de biomassa das cepas LE17 e ITU07 foram, respectivamente, 3,4 e 3 vezes maiores do que as obtidas na condição não otimizada (controle) o que demonstrou a viabilidade do esgoto sanitário como meio alternativo ao cultivo de microalgas. Nos cultivos em meio sintético as produtividades de biomassa das cepas LE17 e ITU07 foram, respectivamente, 48,3 e 22,6 vezes maiores do que as observadas na condição não otimizada (controle). Os conteúdos lipídicos das cepas sob condição otimizada (em meio sintético e no efluente do reator) apresentaram aumento (1%-6,1%) em relação aos observados na condição controle. Assim, houve elevação das produtividades de biomassa das cepas e por consequência, aumento da produção de lipídeos. Os principais ácidos graxos identificados nos lipídeos extraídos foram C16:0 e C18:1. O estudo da remoção de nutrientes pelas microalgas verificou que as cepas são eficientes na remoção de nitrogênio e fósforo tanto do meio sintético quanto do efluente do reator UASB. / Microalgae are interesting source of lipids for biodiesel production. However, their cultivation for this purpose is only economic and environmental feasible if high biomass and lipid productivity are achieved under wastewater use as nutrients source. This research aimed to improve the culture conditions of Chlorococcales microalgae (Desmodesmus and Scenedesmus), considering the lipid content for biodiesel production, the efficiency of nutrient removal by strains, besides the evaluation of wastewater from UASB reactor as an alternative substrate for the cultures. Among 22 strains of microalgae isolated from freshwater environments and stabilization ponds, 2 were selected for culture optimization due to their capacity of accumulating lipids and growing under different physicochemical conditions. Central Composite Design (CCD) was applied to optimization of cell growth conditions of strains LE17 (34,5ºC, pH 8,2 e 200 &#956mol.m-2.s-1) and ITU07 (34ºC, pH 8,2 e 180 &#956mol.m-2.s-1). The optimal conditions were defined and mixotrophic batch cultivations (8 liters) of strains in synthetic medium and in wastewater from UASB reactor (50%) were performed. The biomass productivities of the strains LE17 and ITU07 in domestic wastewater cultivation were, respectively, 3,4 e 3,0 times higher than those obtained in the non-optimized condition (control). This suggested the feasibility of wastewater use as an alternative substrate for the microalgae cultivation. The biomass productivities of the strains LE17 and ITU07 in synthetic medium cultivation were, respectively, 48,3 e 22,6 times higher than those observed in non-optimized condition (control). The lipid content of strains under optimized conditions (in synthetic medium and domestic wastewater) showed an increase (1%-6,1%) compared to those observed in the control condition. Thus, there was an increase in biomass productivities of the strains and consequently, increased production of lipids. The major fatty acids identified in the extracted lipids were C16:0 e C18:1. The study of nutrients removal by microalgae found that the strains are efficient in the uptake of nitrogen and phosphorus from both the synthetic medium and wastewater from the UASB reactor.

Approximately 25% of households in the U.S. treat their wastewater onsite using conventional onsite wastewater treatment systems (OWTS). These systems typically include a septic tank or a series of septic tanks followed by a soil absorption system. They effectively remove biochemical oxygen demand (BOD), total suspended solids (TSS), fats and grease but are not designed to remove significant amounts of nitrogen. High nitrogen loading to coastal and ground waters can be dangerous to aquatic life and public health. Hence, there is a need for advanced onsite wastewater treatment systems that can effectively remove nitrogen. Making enhanced nitrogen removal for OWTS as our primary goal, a laboratory scale Hybrid Adsorption and Biological Treatment Systems (HABiTS) was developed and upon observation of its effective nitrogen removal capacity, a pilot demonstration study with two side-by-side HABiTS, one with recirculation and one without recirculation (only forward flow) were constructed and tested at the Northwest Regional Water Reclamation Facility in Hillsborough County (Florida). HABiTS employ biological nitrogen removal and ion exchange for effective nitrogen removal. HABiTS is a two-stage process which uses nitrification for the oxidation of ammonium to nitrate and ion exchange for ammonium adsorption that helps buffer transient loading and also acts as a biofilm carrier in its stage 1 biofilter and it uses tire-sulfur hybrid adsorption denitrification (T-SHAD) in its stage 2 biofilter. These sulfur pellets help promote sulfur oxidation denitrification (SOD) and tire chips are used for nitrate adsorption during transient loading conditions, as biofilm carriers for denitrifying bacteria, and can also be used as organic carbon source to promote heterotrophic denitrification because they leach organic carbon. For this research, HABiTS without recirculation is considered as the control system and the performance of HABiTS with recirculation was tested for its ability to further enhance nitrogen removal from HABiTS. Nitrified effluent recirculation is a common strategy employed in wastewater treatment for enhanced nitrogen removal. It is the reintroduction of semi-treated wastewater to pass through an anoxic pre-treatment chamber to achieve better quality effluent. Recirculation is said to improve and consistently remove nitrogen at any hydraulic loading rate and/or nitrogen concentration. This is because of the dilution of high BOD septic tank effluent with nitrified effluent which lowers COD:TKN ratio and also improves mass transfer of substrates in the stage 1 biofilter. Recirculation also provides some pre-denitrification in the pre-treatment chamber, thereby reducing nitrogen load on the system. The HABiTS with recirculation (R) was run at 1:1 ratio of nitrified effluent recirculation rate to the influent flow rate for 50 days, and at 3:1 ratio for the remaining period of this research (200 days). The forward flow system (FF) was run under constant conditions throughout the research and comparisons between the two systems were made for different water quality parameters (pH, DO, conductivity, alkalinity, TSS, chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP) and various nitrogen species). The final effluent ammonium results showed that the system with recirculation removed consistently > 80% NH4+-N during 1:1 and 3:1 recirculation ratios whereas the forward flow system achieved 57% removal. Further, an average of 81% total inorganic nitrogen (TIN) removal from the system influent was seen in the recirculation system’s final effluent when compared to an average of 55% in forward flow system’s final effluent. This research explains in detail, the impact of nitrified effluent recirculation on enhanced nitrogen removal in onsite systems and the results presented in this thesis proved that nitrified effluent recirculation provides promising enhanced nitrogen removal in an onsite wastewater treatment system.

Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Sustainability, Environmental and Life Sciences. Includes bibliographical references (leaves 118-134)

Orientador: Rodrigo Braga Moruzzi / Banca: Marcelo de Julio / Banca: Gustavo Henrique Ribeiro da Silva / Resumo: O reúso de águas cinza apresenta-se como uma alternativa de ampliação da oferta de água que pode contribuir para a conservação dos recursos híbridos, perante a escassez da água, não apenas pela qualidade, mas também pela quantidade. Os riscos associados à exposição rotineira ou acidental dessa fonte de alternativa devem, entretanto, ser considerados, para que se possam estabelecer práticas seguras de reúso, uma vez que as águas de reúso podem apresentar patógenos, tais como: vírus, bactérias, protozoários e helmintos. O presente trabalho teve como objetivo avaliar quantitativamente os riscos microbiológicos das diversas fontes de exposições dos usuários a E. coli na água cinza sem tratamento, a fim de definir uma faixa de Valores Máximos Permitidos (VMP) por meio de conceito de riscos aceitáveis 10-3 e 10-6 pppa (por pessoa por ano), para as diversas finalidades de reúso. Para tal, foram avaliadas a exposição, a dose-resposta e a probabilidade de infecção para diferentes finalidades de reúso. O modelo de beta-Poisson foi empregado para avaliação da probabilidade de infecção. A dose infectante (N50), a concentração de microorganismos, a rota de exposição, os volumes ingeridos (acidentalmente e rotineiramente), os parâmetros de interação agente-hospedeiro (α e β), bem como a frequencia de exposição foram avaliados a partir de uma compilação sistemática de dados da literatura. E, por meio da Avaliação Quantitativa de Riscos Microbiológicos (AQRM), o maior risco de infecção identificado decorreu do reúso de águas cinza misturadas para a finalidade de balnearidade e irrigação de culturas alimentares por meio de ingestão de alimentos, incorrendo em risco de aproximadamente 9,9 pessoas de cada dez indivíduos expostos, sem considerar os efeitos de diluição da água. Esse cenário, resultou... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The reuse of greywater is presented as an alternative to increasing the supply of water that can contribute to the conservation of water resources against water scarcity, not only the quality but also the quantity. The risks associated with exposure routine or accidental this alternative source should, however, be considered, so that they establish safe practices of reuse, since reusing water may have pathogens, such as viruses, bacteria, protozoa and helminths. The present study aimed to quantitatively evaluate the microbiological risks of different sources of exposure of users to E. coli in untreated gray water, in order to define a range of Maximum Values Allowed (MVA) through the concept of acceptable risk 10-3 and 10-6 pppy (per person per year), for the various purposes of reuse. To this end, we evaluated the exposure, the dose -response and the probability of infection for different purpose reuse. The beta-Poisson model was used to assess the likehood of infection. The infective dose (N50), the concentration of microorganisms, the route of exposure, the volumes ingested (accidentally and roubinely), the parameters of agent-host interaction (α and β), and the frequency of exposure were evaluated from one systematic compilation of literature. And, through Quantitative Microbiological Risk Assessment (QMRA), the greatest risk of infection identified resulted from the reuse of greywater mixed for the purpose of bathing and irrigation of food crops through food intake, resulting in risk of approximately 9,9 out of ten people exposed individuals, without considering the effects dilution water. This situation has resulted in MVA 5.25 to 105 MPN/100 mL and 3.95 to 39.5 MPN/100 mL, respectively, to an acceptable risk of 10-3 ppy and 0.00 to 0.10 MPN/100 mL and 0.00 to 0.04 MPN/100mL simultaneously to risk of 10-6 pppy. The lowest risk of infection was due... (Complete abstract click electronic access below) / Mestre