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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Selective removal of As(V) from water by polymeric ligand exchange and engineered treatment of spent regenerant

An, Byungryul. Zhao, Dongye. January 2006 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references (p.101-106).
2

Synthetic domestic wastewater sludge as electron donor in the reduction of sulphate and treatment of acid mine drainage

Van den Berg, Francis 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Acid mine drainage (AMD) is wastewater generated by mine and industrial activity with typically high heavy metal and sulphur content potentially resulting in toxic wastewater upon exposure to dissolved oxygen, water and micro-organisms. Due to the hazardous consequences of untreated AMD, treatment methods such as semi-passive biotic treatments, including constructive wetlands and microbial bioreactors were developed. Microbial bioreactors rely on suitable carbon sources such as ethanol, grasses and manure and the creation of anaerobic conditions for the reduction of sulphate, chemical oxidizable organic matter (COD) and to neutralise pH. Domestic wastewater sludge has also been identified as an economical and readily available carbon source that allows the treatment of both AMD and domestic wastewater. A synthetic medium simulating the COD and the biological degradable organic matter (BOD) of domestic wastewater sludge was formulated to exclude variations in the evaluation of domestic wastewater sludge as carbon source in the treatment of AMD. Firstly the BOD and COD of anaerobic domestic wastewater sludge was determined and used as parameters in the formulation of the synthetic medium. A ratio of 1:1 AMD: synthetic domestic wastewater sludge (SDWWS) was the optimum ratio in terms of sulphate and COD removal. Secondly, medical drip bags were used as anaerobic bioreactors to determine the microbial diversity in AMD treated with SDWWS using different variables. Data analyses from next generation sequencing showed that Chlorobium spp. dominated the 90 d pioneer trials at relative percentages of 68 % and 76 %. Transmission electron microscopy (TEM) images and the bright green colour of the liquid contents confirmed the data analyses. Sulphates and COD were removed at > 98 % and > 85 %, respectively. A shorter incubation time was investigated in the 30 d pioneer trial. Chlorobium spp. was dominant, followed by Magnetospirillum spp. and Ornithobacterium spp. The liquid content changed to a dark brown colour. COD and sulphate concentrations were reduced by 60.8 % and 96 %, respectively, within 26 d, after which a plateau was reached. The effect of an established biofilm in the bioreactors showed that Chlorobium spp. also dominated approximately 62 %, in comparison to the 36 % in the 30 d pioneer trial. A sulphate and COD reduction of 96 % and 58 %, respectively, was obtained within 26 d and the liquid content was the same colour as in the 30 d pioneer trial. It is possible that brown Green sulphur bacteria were present. Therefore, although Chlorobium spp. was present at a higher percentage as in the 30 d pioneer trial, the removal of COD and sulphate was similar. During the 30 d trials a white precipitant formed at the top of the bioreactors, consisting primarily of sulphate and carbon that was also indicative of the presence of Chlorobium spp. Incubation at reduced temperature reduced sulphates by only 10 % and COD by 12 % after 17 d, followed by a plateau. Ornithobacterium spp. dominated in the first trial and Magnetospirillum spp. in the second trial. / AFRIKAANSE OPSOMMING: Suur mynwater (SMW) is afvalwater wat deur die myn- en industriële bedryf gegenereer word en bevat kenmerklik hoë konsentrasies swaar metale en swawel wat potensieel in toksiese afvalwater omskep kan word indien blootgestel aan opgelosde suurstof, water en mikro-organismes. Die skadelike gevolge wat blootstelling aan onbehandelde SMW mag hê, het gelei tot semi-passiewe behandelinge wat vleilande en mikrobiese bioreaktors insluit. Mikrobiese bioreaktore maak staat op n geskikte koolstofbron soos etanol, grasse en bemesting en die skep van ‘n anaerobiese omgewing vir die verwydering van sulfate en chemies oksideerbare organiese material (CSB), asook die neutralisering van pH. Huishoudelike afvalwaterslyk is ook uitgewys as ‘n ekonomies geskikte en algemeen beskikbare koolstofbron wat die behandeling van beide SMW en huishoudelike afvalwater toelaat. ‘n Sintetiese medium wat die CSB en biologies afbreekbare organiese materiaal (BSB) van huishoudelike afvalwater slyk naboots is geformuleer om die variasies in die evaluasie van huishoudelike afvalwater slyk as koolstofbron vir die behandeling van SMW, uit te sluit. Eerstens is die BSB en die CSB van huishoudelike afvalwater slyk bepaal en gebruik as n maatstaf vir die formulering van die sintetiese medium. ‘n Verhouding van 1:1 sintetiese huishoudelike afvalwater slyk (SDWWS) en SMW is optimaal ratio i.t.v. die verwydering van sulfate en CSB. Tweedens is mediese dripsakkies as anaerobiese bioreaktore gebruik om die mikrobiese diversiteit in SMW, wat met SDWWS behandel is, te bepaal deur verskeie veranderlikes te gebruik. Tweede generasie DNA-volgorde bepalingstegnieke is gebruik en data analises het gewys dat Chlorobium spp. die 90 d pionier toetslopie domineer met relatiewe persentasies van 68 % en 76 %. Transmissie elektron mikroskopie fotos en die helder groen kleur van die dripsakkies se vloeistof inhoud het die data analises bevestig. Die sulfate en CSB inhoud is onderskeidelik met > 98 % en > 85 % verminder. ‘n Korter behandelingstydperk is ondersoek met n 30 d pionier toetslopie. Chlorobium spp. was dominant, gevolg deur Magnetospirillum spp. en Ornithobacterium spp. Die vloeistof inhoud het na ‘n donker bruin kleur verander. Die CSB en sulfaat konsentrasies is met 60.8 % en 96 % onderskeidelik verminder na 26 dae waarna ‘n plato bereik is. Die effek van ‘n reeds bestaande biofilm in die bioreaktore het gewys dat Chlorobium spp. ook gedomineer het teen ‘n relatiewe persentasie van 62 % in vergelyking met die 36 % in die 30 d pionier toetslopie. ‘n Vermindering in sulfate en CSB van 96 % en 58 % is onderskeidelik is bereik binne 26 d en die vloeistofinhoud was dieselfde kleur as die bioreaktore in die 30 d pionier toetslopie. Dit is moontlik dat die bruin Groen swawel bakterieë teenwoordig was. Daarom, ondanks ‘n groter teenwoordigheid van die Chlorobium spp. teen ‘n relatiewe persentasie in vergelying met die 30 d pionier toetslopie, was die verwydering van CSB en sulfate soortgelyk. Tydens die 30 d toetslopies het ‘n wit neerslag aan die bokant van die bioreaktore gevorm wat hoofsaaklik uit sulfaat en koolstof bestaan het wat ook ‘n aanduiding van die teenwoordigheid van Chlorobium spp. is. ‘n Toetslopie wat by laer temperature uitgevoer is kon die sulfate en CSB met slegs 10 % en 12 % onderskeidelik verminder nadat ‘n plato na 17 d bereik is. Ornithobacterium spp. het die eerste toetslopie gedomineer waar Magnetospirillum spp. die tweede toetslopie gedomineer het.
3

Elaboração de modelo conceitual da degradação de poliacrilamidas (PAM) em compostos nitrogenados aplicado a estudo de caso / A conceptual model for polyacrylamid (PAM) degradation in nitrogen compounds applied to a case study

Santos, Aline Diorio dos 23 April 2018 (has links)
Submitted by Aline Diorio Dos Santos (aline_sduarte@yahoo.com.br) on 2018-06-08T13:12:54Z No. of bitstreams: 1 Dissertação_Aline_23_4_1.pdf: 4336751 bytes, checksum: b04bc967fc2ebdfb6b4208fbc09f7000 (MD5) / Approved for entry into archive by Ana Paula Santulo Custódio de Medeiros null (asantulo@rc.unesp.br) on 2018-06-08T16:42:40Z (GMT) No. of bitstreams: 1 santos_ad_me_rcla.pdf: 4221486 bytes, checksum: 64fef6cda169d205f99769d9b9e4f33f (MD5) / Made available in DSpace on 2018-06-08T16:42:40Z (GMT). No. of bitstreams: 1 santos_ad_me_rcla.pdf: 4221486 bytes, checksum: 64fef6cda169d205f99769d9b9e4f33f (MD5) Previous issue date: 2018-04-23 / Um dos materiais presentes nos lodos oriundos das estações de tratamento (LETAs) é o polímero denominado Poliacrilamida (PAM). Acredita-se que o mesmo seja inerte no solo, porém sua degradação pode estar associada a presença de compostos nitrogenados no solo, como amônio, nitratos e nitritos. Assim, é essencial avaliar a degradação de polímeros no sistema de tratamento de água que auxiliará na seleção e uso de produtos poliméricos no tratamento de água potável. Através da revisão bibliográfica apresentada neste trabalho, foi elaborado um Modelo Conceitual para a disposição de LETAs em aterro, com enfoque na degradação de poliacrilamidas e sua degradação em compostos nitrogenados, validando-o através de dados observados em estudo de caso. Conforme o Modelo Conceitual elaborado, pela via aeróbia, em que os processos de nitrificação podem ser observados, esperavam-se menores valores de pH (resultado da liberação de íons H+), assim como ambiente oxidante para ocorrência do processo de nitrificação (meio aeróbio necessita de oxigênio disponível), enquanto na área fora da zona de nitrificação, esperava-se maior valores de pH, presença maior de OD e maiores valores de Eh, uma vez que o oxigênio não estará sendo consumido pelas bactérias nitrificantes, podendo ainda haver incremento de OD pela recarga do aquífero através das precipitações. Observa-se outra via de degradação anaeróbia, pela reação anamox, em que amônio é oxidado e nitrito reduzido, liberando gás nitrogênio, em ambiente redutor. Adicionalmente, podem ser observados o íon amônio e óxido de manganês e hidróxido de ferro (abundantes no solo) sendo oxidados a nitrogênio gasoso, consumindo íons H+ no meio. A flutuação do nível de água no aquífero pode influenciar as concentrações observadas, através da recarga do aquífero, devido a precipitação e infiltração da água no solo, a espessura do aquífero livre pode se tornar maior, entrando em contato com camadas superficiais de PAM, ocorrendo maior lixiviação dos íons presentes nestas camadas e aumento das concentrações, havendo incremento de massa. Esse fenômeno pode ocorrer em conjunto com os processos biológicos citados, ocorrendo alternância da dissociação dos compostos nitrogenados por meio aeróbio e anaeróbio, conforme OD disponível no meio. Torna-se, portanto, indispensável a discussão sobre quais tipos de polieletrólitos podem ser utilizados no sistema de tratamento de água, pois conforme dados apresentados neste trabalho, a poliacrilamida presente no LETA pode degradar-se em amônio e por sua vez em nitrato por via aeróbia, contaminando o aquífero local, não se apresentando como resíduo inerte como preconizado pelo mercado e alguns autores. / One of the materials present in the sludge originated from water treatment is the polymer polyacrylamide, which some people believes is inert in the soil however its degradation may be associated with nitrogenous compounds in the soil, such as ammonium, nitrates and nitrites. So, it is essential to evaluate the degradation of polymers in the water treatment system due to it will assist in the selection and use of polymer products in the water treatment. Through the bibliographic review presented, a Conceptual Model for the disposition of sludge from water treatment in soil was developed, with the focus on the degradation of polyacrylamides and their degradation in nitrogenous compounds, validating it through data observed in a case study. According to the Conceptual Model elaborated, considering the aerobic route, where the nitrification processes can be observed, were expected lower pH values and oxidizing environment, while in the area outside the nitrification zone were expected higher pH values, presence of dissolved oxygen and reduction environment, once oxygen will not be consumed by nitrifying bacteria and also oxygen could be increased by water from precipitation which recharges the aquifer. Another anaerobic degradation route is observed, considering the anamox reaction, where ammonia is oxidized and nitrite reduced, releasing nitrogen gas, in a reducing environment. In addition, ammonium ion plus manganese oxide plus iron hydroxide can be oxidized to a vapour nitrogen, consuming hydrogen ions. The water level fluctuation in the aquifer can influence the observed concentrations, through the recharge of the aquifer, due to precipitation and infiltration of the water in the soil, the thickness of the free aquifer can become larger, coming into contact with sludge, occurring higher lixiviation of the ions present in these layers and increasing of the concentrations and mass. This phenomenon can occur together with the biological processes, occurring alternation of dissociation of the nitrogen compounds by aerobic and anaerobic, according to dissolved oxygen available. Therefore, it is essential to discuss what types of polyelectrolytes can be used in the water treatment system, due to according to data presented, the polyacrylamide present in the sludge can degrade in ammonium and in turn in nitrate by aerobic process, contaminating the local aquifer, not presenting as inert residue as recommended by the market and some authors.

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