The possible effects of pipe materials on drinking water quality have been analyzed in the distribution system of the water treatment plant of "La La Concepciónâ " in Tegucigalpa, Honduras. "La La Concepciónâ " is a surface water reservoir experiencing biogeochemical cycling of manganese. Black water problems have been reported in the distribution system since 1998. An evaluation of the potential influence that PVC and iron pipes could have on the concentration of iron and manganese in drinking water, the effects caused by the presence of manganese in PVC and iron pipe surfaces, and residual chlorine and Pb concentrations in the distribution system was performed. The sampled neighborhoods received an intermittent service. Water was suspended for 8 hours every day due to water quantity problems in the city. Water and pipe samples were obtained for PVC and galvanized iron pipes because these constitute the majority of the infrastructure used for distribution systems in Honduras. Thermodynamic and kinetic conditions for possible manganese oxidation by chlorine and dissolved oxygen in the distribution system were also evaluated. As expected, total Fe concentrations were greater for first flush conditions from the iron pipe. Water samples obtained from the PVC pipe showed higher total Mn concentrations and more black color than those obtained from the iron pipe for both first flush and continuous flow conditions. Residual chlorine decayed relatively fast along the sampled section of the distribution system. Pb concentrations were detected on water samples obtained from PVC for first flush and continuous flow and on iron pipe for first flush. Preliminary experiments showed that manganese-oxidizing and -reducing bacteria were present in the walls of both PVC and iron pipes. Higher numbers of colony-forming microorganisms were recovered from iron (30-fold more) compared to PVC pipe sections. However, the majority of isolates from the PVC biofilm (8 of 10, 80 %) were capable of Mn-oxidation while only 35 % (11 of 31) of isolates from the iron biofilm sample demonstrated Mn-oxidation. This research demonstrates the importance of the different interactions between water and the infrastructure used for its supply in producing safe drinking water. / Master of Science

Orthophosphates and polyphosphates are rarely present at significant levels in raw water source but are purposefully added to the water in various forms to inhibit corrosion, iron oxidation (red water), or calcium carbonate precipitation (scale formation). Orthophosphates serve as building blocks for polyphosphates, which includes structures in linear chain, branched chains (metaphosphate) and "glassy" polyphosphate polymers. The advantage of polyphosphates over ortho phosphates lies in the fact that they slowly revert to orthophosphates and thus provide corrosion inhibition action over longer period of time in distribution systems. A study was completed for Tampa Bay Water on water distribution systems in a changing water quality environment. Blended orthophosphates was used as one of the corrosion inhibitors to study its effects on metal release and thus justify its application in comparison to other corrosion inhibitors like orthophosphates, zinc orthophosphates and silicates. This work focuses on the study of reversion of polyphosphates to ortho phosphates. A first-order model was developed that quantifies reversion as a function of the hydraulic residence time and initial poly phosphate concentration. The same model was used in two different forms - one for the hybrid lines and the other for single material lines. The results from single material lines (estimated by a non linear least square regression using ANOVA) showed that the reversion rate was highest for galvanized pipe followed by unlined cast iron, lined cast iron and the lowest rate in PVC. The first-order reversion rate constant in PVC was almost two log orders less than galvanized line. A high first-order rate constant for the galvanized pipe could be attributed to a rougher surface, large surface area, reaction with the wall surface, pipe material or a combination of these effects. The results from the hybrid PDSs (estimated by an algebraic manipulation of the first-order reaction) substantially agree with the results obtained from the single material lines, with the exception of the PVC material. The data from the hybrid lines confirms that the reversion rate constant is greatest for exposure to galvanized pipe materials, but the hybrid data indicate that the rate constant associated with PVC is somewhat larger than the constants determined for either LCI or UCI. Once an overall first-order rate expression was established, efforts were made to find a relation between polyphosphate reversions with bulk water quality. None of the major water quality parameters were found to significantly affect the reversion. This observation may be attributable to a similar water quality over the study duration. A positive correlation was found between first-order reversion rate constant and temperature. An empirical equation (modified Arrhenius equation) that relates the first-order reversion rate constant with temperature was developed that showed a strong sensitivity to temperature. The results from this study could be used to predict the stability of polyphosphates in distribution systems with varying pipe materials and temperature.

No description available.

<p>U radu su predstavljeni rezultati&nbsp; ispitivanja biolo&scaron;ke&nbsp;<br />stabilnosti vode za piće primenom rotirajućih prstenastih reaktora (eng.&nbsp;<br />rotating annular reactor, RAR). Pomoću RAR praćen je uticaj odabranih&nbsp;<br />faktora na suspendovani i pričvr&scaron;ćeni mikrobni rast pri kontrolisanim&nbsp;<br />laboratorijskim uslovima koji su simulirali distributivne sisteme. Pored&nbsp;<br />toga, u cilju potpunog razumevanja biolo&scaron;ke stabilnosti vode za piće&nbsp;<br />izvr&scaron;eno je ispitivanje metoda za određivanje biodegradabilne frakcije<br />organske materije, BDOC i AOC test.</p><p>Poređenjem BDOC testova sa nativnom populacijom bakterija&nbsp;<br />pričvr&scaron;ćenom za pesak iantracit utvrđena je efikasnija primena biolo&scaron;kog&nbsp;<br />aktivnog peska. Primenom peska za inokulaciju uzorka, vrednost BDOC&nbsp;<br />u podzemnoj vodi sa teritorije srednjeg Banata iznosila je 1,27 mgC/l. U<br />ispitivanju AOC testa sa suspendovanim standardnim kulturama&nbsp;<br />Pseudomonas fluorescens P17 (ATCC 49642) i Spirillum sp. NOX&nbsp;<br />(ATCC 49643), AOC iskori&scaron;ćen od strane NOX je imao veću vrednost u&nbsp;<br />odnosu na P17, &scaron;to pokazuje da su karboksilne kiseline dominantan&nbsp;<br />supstrat za rast. Vrednost AOC u tretiranoj podzemnoj vodi iznosila 32&nbsp;<br />&mu;g acetat-C/l. Veće vrednosti BDOC ukazuju na prisustvo jedinjenja&nbsp;<br />veće molekulske mase u ovoj frakciji u odnosu na AOC frakciju&nbsp;<br />biodegradabilne organske materije.</p><p>U ispitivanju biostabilnosti podzemne vode sa teritorije srednjeg&nbsp;<br />Banatatokom tretmana, najveća količina biofilma je razvijena u RAR sa&nbsp;<br />ozoniranom vodom (13,30 CFU/cm²), &scaron;to potvrđuje efekte ozonizacije na&nbsp;<br />biodegradabilnost organske materije i ponovni rast mikroorganizama.&nbsp;<br />Tokom tretmana zabeleženo je variranje razvoja biofilma, pri čemu je&nbsp;<br />najmanji stepen rasta biofilma uočen u RAR sa vodom nakon GAC&nbsp;<br />filtracije (1,10 CFU/cm²).</p><p>Tokom mikrobne kolonizacije test-pločica RAR pri laminarnom i&nbsp;<br />turbulentnom protoku uočen je sličan trend rasta bakterija u biofilmu u sintetičkoj sme&scaron;i organskih i neorganskih nutrijenata. Međutim, tokom dominacije suspendovanog rasta u sistemu voda-biofilm pri neprotocnim uslovima, pona&scaron;anje biofilmova razvijenih pri protočnim (laminarnim i turbulentnim) uslovima je bilo različto. Uočen je manji udeo bakterija prisutnih u vodenoj fazi kod biofilma nastalim pri turbulentnom protoku u odnosu na veće oslobađanje ćelija iz biofilma nastalim pri laminarnim uslovima, nakon 48h 78% i 89% suspendovanih bakterija, redom. Ovi rezultati pokazuju da su biofilmovi razvijeni pri turbulentnom protoku snažniji, stabilniji &nbsp; i jače pričvr&scaron;ćeni nego pri laminarnom protoku.</p><p>Tokom praćenja sekundarne kolonizacije odvojenih ćelija biofilma&nbsp;<br />uočeno je da se primarni biofilm pona&scaron;a kao stalni rezervoar ćelija koje&nbsp;<br />su sposobne da zauzmu nove povr&scaron;ine vrlo brzo pri različitim&nbsp;<br />hidrodinamičkim uslovima. Brojnost bakterija u biofilmu razvijenom na&nbsp;<br />sekundarnim test-pločicama nakon 24 h iznosila je 32000&plusmn;1200&nbsp;CFU/cm^2&nbsp;<br />u odnosu na 16&plusmn;1 CFU/cm^2&nbsp;primarne test-pločice. Ustanovljen&nbsp;<br />je izraženiji potencijal kolonizacije novih povr&scaron;ina odvojenim želijama iz&nbsp;<br />primarnog biofilma koji je formiran pri turbulentnim uslovima u odnosu&nbsp;<br />na laminarne uslove.</p><p>Proces stvaranja biofilma na test-pločicama od nerđajućeg čelika&nbsp;<br />(SS), polivinilhlorida(PVC) i polietilena(PE) je bio vrlo sličan. Samo&nbsp;<br />debljina biofilma je bila veća na PE (4,0-5,5 kg/m³) nego na SS i PVC&nbsp;<br />test-pločicama (2,7-3,6 kg/m^3&nbsp;i 2,8-3,9 kg/m³, redom). Ustanovljen je&nbsp;<br />uticaj materijala cevi na rast biofilma u RAR snabdevanim vodom iz&nbsp;<br />distributivnog sistema grada Novog Sada, naročito za vreme početne faze&nbsp;<br />procesa. Biofilmovi formirani na različitim materijalima u RAR su uticali&nbsp;<br />na mikrobiolo&scaron;ki kvalitet vode, zavisno od njihove bakterijske gustine.&nbsp;</p><p>SEM analiza potvrdila je prisustvo biofilma na test-pločicama u&nbsp;<br />eksperimentima, ukazujući na uspe!nu primenu RAR u ispitivanju&nbsp;<br />biofilma i biostabilnosti vode za piće.</p><p>Rezultati dobijeni tokom ispitivanja ukazuju da se primenom&nbsp;<br />odabranih i optimizovanih, zavisno od cilja ispitivanja i vrste uzorka,&nbsp;<br />BDOC i AOC testova može efikasno definisati biolo!ka stabilnost vode&nbsp;<br />za piće. Pored toga, sistematski pristup odabiru odgovarajućih materijala&nbsp;<br />cevi, koji je zasnovan na pouzdanim testovima i definisanim&nbsp;<br />kriterijumima, može se primeniti u cilju osiguravanja kvaliteta vode sa&nbsp;<br />mikrobiolo&scaron;kog aspekta.</p><p>Ispitivanja su pokazala uspe&scaron;nu primenuRAR u simulaciji&nbsp;<br />mikrobnog rasta u cevima pri kontrolisanim laboratorijskim uslovima i&nbsp;<br />značaj istovremenog ispitivanja imobilisanog i suspendovanog rasta u&nbsp;<br />definisanom hidrodinamičkom sistemu.&nbsp; Primena RAR kao model biofilma je ukazala na njegov značaj u ispitivanju potencijala ponovnog naseljavanja povr&scaron;ina otkinutih delova i/ili pojedinačnih ćelija biofilma za uspostavljanje efikasne kontrole mikrobnih problema u distributivnim sitemima vode za piće.</p> / <p>This thesis presents theresults of investigation of drinking water biostability using the&nbsp; rotating annular reactor (RAR). The effects of selected factors on the suspended and attached microbial growth under controlled laboratory conditions that simulated the&nbsp;distribution systems were monitored using RAR. In addition, in order to completeunderstanding of the drinking water biological stability,&nbsp;methods for determining biodegradable organic matter fractions, BDOC&nbsp;and AOC methods were tested.</p><p>Comparing the BDOC tests with the native population of bacteria&nbsp;attached to sand and anthracite, a better application of biologically active&nbsp;sand was established. Using BDOC test with sand, the BDOC value in&nbsp;groundwater from the territory of the Central Banat (Republic of Serbia)&nbsp;was 1.27 mgC/L. In the investigation of AOC tests with standard&nbsp;<br />suspended culture of Pseudomonas fluorescens P17(ATCC 49642) and&nbsp;Sprillumsp. NOX (ATCC 49643), AOC utilized by NOX had a higher&nbsp;value compared to the P17, which shows that the carboxylic acid are&nbsp;dominant substrate for growth. The AOC value in the treated ground&nbsp;water was 32 &mu;g acetate-C/L. The higher BDOC values indicate the&nbsp;presence of higher molecular weight compounds in this fraction&nbsp;compared to the AOC biodegradable fraction of organic matter.&nbsp;</p><p>In the investigation of biostability during treatment of&nbsp;groundwater from the territory of the Central Banat (Republic of Serbia),&nbsp;the largest amount of biofilm was developed in the RAR with ozonated&nbsp;water (13.30 CFU/cm²), confirming the effects of ozonation on organic&nbsp;matter biodegradability and microbial regrowth. During treatment the&nbsp;<br />variation of biofilm development was detected and in the RAR with water after GAC filtration the lowest level of biofilm growth (1.10 CFU/cm²) was observed.&nbsp;</p><p><span style="font-size: 12px;">During the microbial colonization of the RAR test-coupons under&nbsp;</span><span style="font-size: 12px;">laminar and turbulent flow, the similar trend of growth of bacteria in the&nbsp;</span><span style="font-size: 12px;">biofilm in synthetic mixture of organic &nbsp;and inorganic nutrients was&nbsp;</span><span style="font-size: 12px;">observed. However, the higher numbers of immobilized bacteria under&nbsp;</span><span style="font-size: 12px;">the turbulent conditions in the same growth period (16 days) were&nbsp;</span><span style="font-size: 12px;">recorded. During the domination of suspended growth in water-biofilm system under &nbsp;non-flow conditions, the behavior of biofilms developed under flow (laminar and turbulent) conditions were different. There was a smaller proportion of bacteria present inthe aqueous phase of the biofilm formed under the turbulent flow over a larger release of cells &nbsp;from biofilms formed under laminar conditions, after 48h 78% and 89% of the suspended &nbsp;bacteria, respectively. These results indicate that biofilms developed under turbulent flow &nbsp;were stronger, more stable and more strongly attached than the ones under laminar flow.</span></p><p>During monitoring of the secondary colonization of the dettached&nbsp;biofilm cells, it was noted that the primary biofilm was a constant&nbsp;reservoir of cells that are able to occupy the new areas very quickly&nbsp;under different hydrodynamic conditions. The abundance of bacteria in&nbsp;the biofilm developed on the secondary test-coupons after 24 h was 32&nbsp;<br />000&plusmn;1200 CFU/cm² compared to 16&plusmn;1 CFU/cm²on the primary test-coupons. A stronger potential for colonization of new areas by dettached&nbsp;cells from the primary biofilm formed under the turbulent conditions in&nbsp;comparison to laminar conditions was found.&nbsp;</p><p>The biofilm formation processes on SS, PVC and PE test-coupons&nbsp;werevery similar. Only biofilm thickness was greater on the PE (4.0 to&nbsp;5.5 kg/m³) than the SS and PVC &nbsp;test-coupons (2.7 to 3.6 kg/m³ and 2.8 to&nbsp;3.9 kg/m³, respectively). There was a slight influence of pipe material on&nbsp;the biofilm growth, especially during the initial stages of the process.&nbsp;Biofilms formed on different materials in the RAR with water from the&nbsp;distribution system of the city of Novi Sad (Vojvodina, Republic of&nbsp;Serbia) have showed the influence on the microbiological quality of&nbsp;water, depending on their bacterial density.</p><p>SEM analysis confirmed the biofilm presence on test-coupons in&nbsp;the experiments, indicating the successful implementation of RAR in the&nbsp;examination of biofilm and drinking water biostability.&nbsp;</p><p><span style="font-size: 12px;">The results obtained during the investigations indicate that the&nbsp;</span><span style="font-size: 12px;">application of selected and optimized, depending on the test objective&nbsp;</span><span style="font-size: 12px;">and sample types, BDOC and AOC tests can effectively define the&nbsp; biological stability. In addition, a systematic approach for &nbsp;electing appropriate pipe materials, which is based on reliable tests and defined criteria, specific for the investigated drinking water distribution system can be applied to ensure &nbsp;he water quality from a microbiological point of view.</span></p><p>The investigations have shown the successful application of RAR&nbsp;in the simulation of microbial growth in the pipes under controlled&nbsp;laboratory conditions as well as the importance of simultaneous&nbsp;examination of immobilized and suspended growth under defined&nbsp;hydrodynamic system. Implementation of RAR as amodel biofilm&nbsp;indicated its importance in examining the potential resettlement area by&nbsp;dettached parts and/or individual biofilm cells to establish effective&nbsp;control of microbial problems in the drinking water distribution system.&nbsp;</p>