M. Tech. (Department of Biotechnology, Faculty of Applied and Computer Sciences) Vaal University of Technology. / Pollution of aquatic systems by wastewater containing pathogens, heavy metals and high concentrations of nutrients is of great concern due the ecological risks they impose. The toxic effects of metals may occur even at low concentrations because of potential bio magnification in the food chain. Excessive nutrients cause algal blooms which depletes oxygen and prevents sunlight from penetrating into the water, thereby killing fish and other aquatic organisms. This study investigated the pollutant removal efficiency of a riparian wetland located in Sebokeng, Emfuleni local municipality, South Africa. The study was carried out to assess the water quality of a wetland located downstream of the Sebokeng wastewater treatment plant by monitoring and analysing the physico-chemical parameters which included pH, temperature, electrical conductivity, nutrient levels (nitrates, phosphates, nitrites) and heavy metals. The water samples were collected from the effluent discharge of the treatment plant, upstream and downstream of the wetland. Plant uptake of heavy metals in a riparian wetland, nitrification as well as denitrification processes have been historically recorded as the main processes that contribute to the high removal of pollutants in a wetland. The contaminant concentrations of the influent and the effluent were used to estimate the wetland efficiency in improving the water quality that passes through it and its potential effects on improving the quality of irrigation waters. The heavy metals of interest included Al, Cd, Cr, Cu, Fe, Pb, Mn and Zn. Most heavy metals within the wetland occurred at low concentrations (lower than detectable limits and within the discharge limits for irrigation purposes). The results indicate that the average removal efficiencies for Electrical Conductivity (EC), Total coliforms (TC), E. coli, BOD5, COD, TSS, carbonate hardness, aluminium, iron, manganese, copper, nitrite, nitrate, sulfate and ortho-phosphate were 43 %, 51%, 85%, 60%, 61%, 61%, 21%, 67%, 52%, 51%, 83%, 56%, 89%, 49% and 54% respectively. The study showed that this wetland can provide up to 89% removal efficiency of pollutants. Of particular significance was the high pathogen and nutrient removal efficiency. A t-test was performed in order to determine the statistical significance of the wetland pollutant removal efficiencies. All p-values calculated were well below 0.05 and the removal efficiencies are therefore considered statistically significant. For this particular ecosystem the findings show that there is no great concern about metal pollution since most of the metals tested for were below the minimum limit for irrigation stipulated by the South African water regulation department (DWAF 1996a). Therefore, the wetland effluent water qualifies for both agriculture and landscape irrigation. Future considerations in choosing to use wetlands as a polishing facility for wastewater treatment systems are highlighted in the study.

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Master of Science / Department of Civil Engineering / Natalie Mladenov / In the United States approximately 37% of the 4 trillion kWh of electricity is generated annually by combusting coal (USEPA, 2013). The abundance of coal, ease of storage, and transportation makes it affordable at a global scale (Ghose, 2009). However, the flue gas produced by combusting coal affects human health and the environment (USEPA, 2013). To comply with federal regulations coal-fired power plants have been implementing sulfur dioxide scrubbing systems such as flue gas desulfurization (FGD) systems (Alvarez-Ayuso et al., 2006). Although FGD systems have proven to reduce atmospheric emissions they create wastewater containing harmful pollutants. Constructed wetlands are increasingly being employed for the removal of these toxic trace elements from FGD wastewater. In this study the effectiveness of using a constructed wetland treatment system was explored as a possible remediation technology to treat FGD wastewater from a coal-fired power plant in Kansas. To simulate constructed wetlands, a continuous flow-through column experiment was conducted with undiluted FGD wastewater and surface sediment from a power plant in Kansas. To optimize the performance of a CWTS the following hypotheses were tested: 1) decreasing the flow rate improves the performance of the treatment wetlands due to an increase in reaction time, 2) the introduction of microbial cultures (inoculum) will increase the retention capacity of the columns since constructed wetlands improve water quality through biological process, 3) the introduction of a labile carbon source will improve the retention capacity of the columns since microorganisms require an electron donor to perform life functions such as cell maintenance and synthesis. Although the FGD wastewater collected possessed a negligible concentration of arsenic, the mobilization of arsenic has been observed in reducing sediments of wetland environments. Therefore, constructed wetlands may also represent an environment where the mobilization of arsenic is possible. This led us to test the following hypothesis: 4) Reducing environments will cause arsenic desorption and dissolution causing the mobilization of arsenic. As far as removal of the constituents of concern (arsenic, selenium, nitrate, and sulfate) in the column experiments, only sulfate removal increased as a result of decreasing the flow rate by half (1/2Q). In addition, sulfate-S exhibited greater removal as a result of adding organic carbon to the FGD solution when compared to the control (at 1/2Q). Moderate selenium removal was observed; over 60% of selenium in the influent was found to accumulate in the soil. By contrast, arsenic concentrations increased in the effluent of the 1/2Q columns, most likely by dissolution and release of sorbed arsenic. When compared to the control (at 1/2Q), arsenic dissolution decreased as a result of adding inoculum to the columns. Dissolved arsenic concentrations in the effluent of columns with FGD solution amended with organic carbon reached 168 mg/L. These results suggest that native Kansas soils placed in a constructed wetland configuration and amended with labile carbon do possess an environment where the mobilization of arsenic is possible.

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Timothy D. Keane / Urbanization has lead to environmental degradation in most of the world’s great cities. With the degradation of natural systems comes a reliance on man-made and engineered systems to perform functions vital to cities such as water treatment, the filtering of pollutants, flood mitigation, temperature control, and erosion prevention; functions formerly performed by natural systems. Relying on man-made operations to perform essential services comes at a cost, both in terms of monetary costs and in the resources needed to construct and operate them. New Orleans is a prime example of a city that has greatly altered the ecosystems that formerly existed on the site and has had to rely on human engineering for its survival. Instead of the mosaic of freshwater marshes, wooded swamps, wet meadows, and bottomland forests that once comprised New Orleans and allowed for the diffusion, evaporation, and infiltration of floodwater; present day New Orleans has had to rely on a system of levees and pumps to keep the City dry. These pumps and levees have allowed New Orleans to expand and prosper but failures in the flood control system have also lead to great disasters, Hurricane Katrina and the related flood in 2004 being the latest. Implementing permaculture designs to New Orleans will buffer the City from the effects of hurricanes and flooding and decrease its reliance on city services. These permaculture designs recreate key elements of the natural systems that formerly existed in New Orleans and attempt to again create spaces in the City were stormwater can safely be detained without damaging property and that allow the stormwater to infiltrate into the soil. At the same time these permaculture designs would enhance the character and uniqueness that makes New Orleans one of the world’s great cities.

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Timothy D. Keane / All along the Gulf Coast, wetlands are disappearing due to saltwater intrusion from the draining of freshwater wetlands. Louisiana has about 40 percent of the coastal wetland in the lower 48 states but is currently losing approximately 24 square miles of wetlands a year (Louisiana Coastal 2009). Studies have shown that wetlands can help reduce the impact of a storm surge during a hurricane and have a cleansing ability from air to water. An increase in hurricane intensities due to climate change will likely result in bigger storm surges. Without wetlands to diffuse storm surges, disasters like Hurricane Katrina will recur. Cities spend millions of dollars on treating wastewater and stormwater with facilities and chemicals. Wetlands can treat wastewater through different processes without using chemicals, thus reducing costs and increasing sustainability. Bayou Bienvenue is a wetland located in New Orleans. This wetland was once a freshwater cypress swamp, but due to saltwater intrusion from the construction of Intracoastal Waterway and Mississippi River Gulf Outlet, has turned into a brackish lake. This wetland is separated from the Lower 9th Ward with a levee that creates a visual barrier which results in local residences not knowing that there is a former wetland behind the levee. Bayou Bienvenue’s Ecological Park’s discovery center with educational programs about successional wetland landscapes will educate people about the importance of wetlands to New Orleans. The restored of the bayou will be a landscape that functions as infrastructure through the treatment of stormwater and wastewater. The bayou will aid in reducing storm surge impacts, provide wildlife habitat, become part of schools’ curricula within the 9th Ward, stimulate the local economy and provide a community park for people to enjoy. Bayou Bienvenue’s Ecological Park will help spur further wetland projects of this caliber in and around New Orleans.

Master of Arts / Department of Geography / John A. Harrington Jr / The Rainwater Basin Wetland Complex of south-central Nebraska is a region of great climatic variability, as well as tremendous ecological importance. The Rainwater Basin Wetland Complex is located at the focal point of the Central North American migratory bird flyway, and supports in excess of twelve million birds during the spring migration period. The physical landscape has been significantly altered from its pre-settlement state by agricultural conversion via the draining of over ninety percent of the native wetlands. Due to the region’s highly variable continental climate, interannual wetland water levels are also highly variable and currently unpredictable. I have used multi-year analysis, including the construction of a regional water budget assessment, to study which climatic variables play the most crucial role in the late-winter filling of wetlands. Research objectives were met by analyzing ten cold season (Oct – Feb) climatic variables and an annual measure of wetland area for five years, in order to better understand possible climatic drivers of wetland hydrologic functioning levels in March. Longer time series of winter season climatic information were also assessed to help place the recent and more detailed analysis into a longer climatic context. Research results will aid local management agencies in the future through enhanced knowledge of how climatic variation impacts wetland function. Seasonal precipitation and temperature was favored by the linear regression analysis, while the multiple regression analysis placed higher emphasis on February evapotranspiration rates, February snow depth, and February snowfall. Lastly, the hydrologic water budget that was created for the study area had several highly correlated output variables with basin-wide flooded hectares, particularly annual snow storage.

<p>Water and sanitation are two of the world's most urgent current challenges (Elimelech, 2006). With a population racing towards seven billion people, over one sixth of the human population does not have access to adequate water and sanitation. Drinking water is inaccessible for approximately 783 million people living in the developing world (WHO, 2014). This is especially critical for people at risk of exposure to deadly pathogens such as <italic>Vibrio cholerae</italic>, <italic>Shigella</italic>, and <italic>Salmonella</italic>, such as those living in Haiti as <italic>Vibrio cholerae</italic> is now ubiquitous (Enserink, 2010). On the sanitation side, more than 2.5 billion people in the world still lack access to adequate resources (WHO, 2014). Almost half of these people have access to no sanitation facilities at all and practice open defecation (WHO, 2014). Thousands of small children still die every day from preventable diseases caused by inadequate sanitation (WHO, 2014). As global climate change is expected to exacerbate these issues, there is an urgent need for the development of sustainable treatment technologies to ensure a better tomorrow for our world (Ford, 1999). Safe water and sanitation technologies, while often disjointed, should be considered together as pathogens transmitted via drinking water are predominantly of fecal origin (Ashbolt, 2004; Montgomery, 2007). </p><p>In this dissertation project, I explore the use of both drinking water and wastewater treatment technologies which are cost effective and rely on locally available materials in low-income countries. For the drinking water treatment side, I focus on the use of biosand filters in Haiti with a specific interest in understanding their ability to remove the pathogen <italic>Vibrio cholerae</italic>, the causative agent for cholera. The wastewater treatment technology consists of biofilters packed with cocopeat, a waste product generated during coconut husk processing, and I investigate their use for the treatment of septic tank effluent in Vietnam. Both of these projects combine lab and field work. The specific objectives of this dissertation project are to 1) compare the removal efficiency of <italic>V. cholerae</italic> to indicator bacteria in field biosand filters and determine the parameters controlling removal; 2) investigate the correlation between removal efficiency of pathogens in field biosand filters having operated for varying lengths of time to schmutzdecke bacterial composition and influent water characteristics; 3) determine the effect of number of charges, total organic carbon loading, and schmutzdecke composition on <italic>V. cholerae</italic> removal efficacy; 4) isolate the effect of biological removal mechanisms and physical/chemical removal mechanisms on <italic>V. cholerae</italic> removal efficiency and determine the correlation to TOC concentration in water; 5) evaluate cocopeat as a packing medium for biofilters in terms of nitrogen, phosphorus and biological oxygen demand removal from simulated wastewater as compared to other traditional packing media; and 6) conduct an assessment of cocopeat-packed, vertical flow constructed wetlands treating septic tank effluent in the Mekong Delta of Vietnam. </p><p>In the first part of this dissertation, biosand filters in the Artibonite Valley of Haiti, the epicenter of the cholera epidemic, were tested for total coliform and <italic>V. cholerae</italic> removal efficiencies. In addition, schmutzdecke samples were collected in order to measure the amount of EPS in the biofilm, as well as characterize the microbial community. Total coliform and <italic>V. cholerae</italic> concentration were measured using novel membrane filtration technique methods. It was found that total coliform concentration does not indicate <italic>V. cholerae</italic> concentration in water, and total coliform removal efficiency does not indicate <italic>V. cholerae</italic> removal efficiency within biosand filters. Additionally, parameters controlling biosand filter performance include: schmutzdecke composition, time in operation, and idle time.</p><p>In the second part of this dissertation, <italic>V. cholerae</italic> challenge tests were performed on laboratory-operated biosand filters receiving high, medium or low TOC influents in order to determine the effect of number of charges, total organic carbon loading, and schmutzdecke composition on <italic>V. cholerae</italic> removal efficacy, as well as to isolate the effect of biological removal mechanisms and physical/chemical removal mechanisms on <italic>V. cholerae</italic> removal efficiency and determine the correlation to TOC concentration in water. To this end, three biosand filters were operated in the lab. Each received lake water or diluted lake water with high, medium or low concentrations of TOC. After being charged once per day for 6 days, the filters were charged with four consecutive charges of pure cultures of <italic>V. cholerae</italic> suspended in PBS buffer, at concentrations of 10<super>2</super>, 10<super>3</super>, 10<super>5</super>, and 10<super>7</super> cfu/mL. This challenge was repeated each time the filters received an additional 6 charges, up to 66 total charges. This was done to determine how number of charges, TOC loading, and schmutzdecke composition affects removal efficiency. Schmutzdecke was analyzed for amount of EPS and microbial community. It was found that parameters controlling biosand filter performance include: TOC loading, schmutzdecke composition, time in operation, and physical/chemical attachment. Additionally, it was shown that physical/chemical attachment is critical during startup, especially at low TOC concentrations. At steady state, physical/chemical attachment is more important than schmutzdecke effects in filters receiving low TOC, and schmutzdecke effect is more important than physical/chemical attachment in filters receiving high TOC.</p><p>For the third section of this dissertation, columns packed with cocopeat, celite, or sphagnum peat were charged with simulated wastewater and removal efficiencies of nitrogen, phosphorus, and biological oxygen demand were measured. Additionally, different redox zones were tested to determine if cocopeat could successfully accomplish nitrification and denitrification. It was found that cocopeat is comparable to traditional packing media and can successfully accomplish nitrification and denitrification in the treatment of synthetic wastewater.</p><p>In the final section of this dissertation, constructed wetlands were built and packed with cocopeat to determine if cocopeat is a suitable packing media in constructed wetlands treating wastewater in Vietnam. Removal efficiencies of nitrogen, phosphorus, and biological demand were measured. Microbial community samples were collected periodically in order to analyze community shifts between wetlands and over time. This work concluded that cocopeat can be used successfully as a packing media in constructed wetlands treating wastewater for the removal of nitrogen, phosphorus, and total coliform.</p><p>Overall, this dissertation work contributes to the body of knowledge on point-of-use water and wastewater technologies. The biosand filter was studied in both lab and field conditions and it was found that total coliform is not a reliable indicator for <italic>V. cholerae</italic>, and that there are several factors controlling biosand filter performance, including idle time, TOC, filter time in operation, physical/chemical attachment, and schmutzdecke composition. Cocopeat was studied for its ability to promote nitrification and denitrification in lab-scale vertical flow columns treating synthetic wastewater. It was shown that cocopeat achieved similar levels of nitrification and denitrification as traditional packing media. Finally, cocopeat packed vertical flow constructed wetlands were operated in Vietnam for the treatment of septic tank effluent. This setup proved effective for the removal of nitrogen, phosphorus, and total coliform in the treatment of wastewater.</p> / Dissertation

Thesis (MScConsEcol)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Wetland systems provide vital hydrological ecosystem goods and services to mankind. When wetlands are transformed, through invasion by alien plants or replaced with agriculture, natural capital is lost, and the system is no longer able to provide the same quality of hydrological ecosystem services. Natural capital can be restored, but it involves substantial financial investment, and there is no guarantee that these hydrological ecosystem services will be fully recovered. This thesis aimed to investigate the hydrological impact of the land-cover changes in the Kromme River Catchment over the last 50 years, by using a combination of mapping and hydrological modelling techniques. We hypothesized that wetland loss in the Kromme has resulted in a shift in the flow regime, greater responsiveness to floods as a result of less storage, lower baseflow, and reduced water quality. We also hypothesised that the riparian invasion by Acacia mearnsii has caused flow reductions as a result of increased evaporation relative to the wetlands. Modelling results predict that over the past 50 years, the transformation of the floodplain wetlands in the Kromme River has shifted the flow regime, reducing baseflows and increasing the responsiveness of the catchment to extreme rainfall events. The invasion of A. mearnsii over time has also been predicted to have caused a reduction in river flow. Various restoration scenarios were considered, however if the Kromme were to be restored back to a land-cover state comparable to the 1950’s, 26.9 km2 (65.1%) of A. mearnsii would have to be cleared, and 5.2 km2 (34.2%) of the wetlands would have to be restored. The hydrological benefits would include a predicted increase in riverflow (42 mm/a), baseflow (2.9 mm/a), an increase in flood protection and improved water quality. This restoration strategy could be regarded as a type of insurance plan, and the benefits gained in terms of increased ecosystem service delivery would be the insurance premium. In conclusion it appears that restoration, insuring natural capital in the Kromme River, would provide significant economic returns on investment. / AFRIKAANSE OPSOMMING: Moeraslandstelsels voorsien die mens van noodsaaklike hidrologiese ekosisteemgoedere en -dienste. Wanneer moeraslande verander word, hetsy deur die indringing van uitheemse plante of vervanging met landboubedrywighede, gaan natuurlike kapitaal verlore en kan die stelsel nie meer dieselfde gehalte hidrologiese ekosisteemdienste lewer nie. Hoewel natuurlike kapitaal herwin kan word, behels dit beduidende finansiële belegging, en is daar boonop geen waarborg dat die hidrologiese ekosisteemdienste ten volle sal herstel nie. Hierdie tesis het ten doel gehad om die hidrologiese impak van die grondbedekkingsveranderinge in die Krommerivier-toeloopgebied oor die afgelope 50 jaar met behulp van ’n kombinasie van karterings- en hidrologiese modelleringstegnieke te ondersoek. Die hipotese was dat moeraslandverlies in die Kromme tot ’n verandering in die vloei-regime, hoër responsiwiteit op erge reënval as gevolg van minder bergingsruimte, ’n laer basisvloei en swakker watergehalte gelei het. Daar is voorts gehipoteseer dat die oewerindringing deur Acacia mearnsii ’n verlaging in vloei veroorsaak het weens ’n toename in verdamping uit die moeraslande. Modelleringsresultate dui daarop dat die transformasie van die vloedvlakte-moeraslande in die Krommerivier oor die afgelope 50 jaar die vloei-regime verander het, basisvloei verminder het en die toeloopgebied se responsiwiteit op erge reënval verhoog het. Die indringing van A. mearnsii het ook volgens aanduidings mettertyd ’n vermindering in riviervloei tot gevolg gehad. Verskeie herstelscenario’s is oorweeg. Om die grondbedekking in die Kromme te herstel tot wat dit in die 1950’s was, moet 26,9 km2 (65,1%) van die A. mearnsii verwyder en 5,2 km2 (34,2%) van die moerasland herwin word. Die hidrologiese voordele kan ’n verwagte toename in riviervloei (42 mm/a) en basisvloei (2,9 mm/a), ’n toename in vloedbeskerming sowel as beter watergehalte insluit. Hierdie herstelstrategie kan as ’n soort versekeringspolis beskou word, en die voordele verbonde aan beter ekosisteemdienslewering as die versekeringsuitbetalung. Ten slotte blyk dit dat die herstel van die Kromme, en die gepaardgaande versekering van natuurlike kapitaal, beduidende ekonomiese opbrengste op belegging sal meebring.

Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Constructed wetlands have been widely used in the treatment of industrial and domestic wastewater to reduce biological and chemical oxygen demand (BOD and COD), to remove nitrate and enteric viruses as well as to generally improve water quality. Distillery wastewater has a complex character due to high concentrations of sugars, lignins, hemicellulose, dextrins, resins, polyphenols and organic acids, leading to a high COD that may exceed 100 000 mg/L. The potential application for the treatment of distillery wastewater by means of constructed wetlands is relatively unexplored. In 1999 a study was initiated at Distell Goudini distillery, Western Cape, South Africa, to explore the possibility of using constructed wetlands to treat distillery wastewater. It was found that constructed wetlands do have the ability to treat distillery wastewater providing that the influent COD does not exceed 15 000 mg/L for extended periods and the correct substrate material is used. The present study expanded on the above-mentioned study and specifically aimed to provide information on the microbiological controls in wetland systems in an applied sense that may contribute to improved treatment efficiency. Furthermore, this project aimed to contribute to our fundamental understanding of the microbial ecology of constructed wetlands used for the treatment of distillery wastewater. This study revealed that a highly dynamic microbial composition exists within wetlands. Furthermore it was found that wetlands can efficiently remove COD even though a low degree of similarity exists between microbial communities in various zones of the same wetland and those between different wetlands, as well as low similarity between communities sampled from the same zone over time. This demonstrates that it will be difficult to define the ‘ideal’ degradative community in terms of microbiological criteria and serves as a reminder that various indicators should be considered for monitoring system health. Furthermore the shifts in microbial community composition illustrate the ability of microbial communities to adapt to changes in the environment without compromising their functional efficacy. When studying the attached microbial communities within wetland systems it was found that different morphotypes are detected at certain stages of biofilm development while some organisms are present at most phases of biofilm formation. Measurement of CO2 production and dissolved organic carbon (DOC) removal in laboratory scale columns showed that grazing protists had a notable effect on overall microbial activity and that organic loading influenced these predator-prey interactions. Interestingly, increased clogging of pores occurred in the presence of protists, resulting in reduced flow through the porous matrix. Terminalrestriction fragment length polymorphism (T-RFLP) analysis of biofilms on gravel in experimental wetlands indicated that the presence of protists and algae had an effect on the microbial community composition. Scanning electron microscopy (SEM) showed that the presence of algae also had an influence on biofilm structure suggesting that the algae provided labile nutrients that were utilized by the bacterial and yeast members of the community. Finally, augmentation with a commercial mixture or microbial populations isolated from distillery effluent demonstrated that the concentration at which supplements are applied influence degradative efficiency. / AFRIKAANSE OPSOMMING: Kunsmatige vleilande word wêreldwyd gebruik in die behandeling van indusriële en huishoudelike afvalwater om biologiese en chemiese suurstof aanvraag (BSA en CSA) te verminder, om nitrate en ingewandsvirusse te verwyder asook om waterkwaliteit in die algemeen te verbeter. Distilleerafvalwater het komplekse eienskappe as gevolg van hoë konsentrasies suiker, lignien, hemisellulose, dekstrien, harpuis, polifenole en organiese sure, wat lei tot ‘n hoë CSA wat 100 000 mg/L kan oorskry. Daar is tot op hede relatief min studies gedoen oor die potensiële gebruik van kunsmatige vleilande vir die behandeling van distilleerafvalwater. In 1999 is ‘n studie by Distell Goudini distilleeraanleg in die Wes Kaap van Suid Afrika onderneem om die moontlikheid van kunsmatige vleilande vir die behandeling van distilleerafvalwater te bestudeer. Daar was bevind dat kunsmatige vleilande die vermoë het om distilleerafvalwater te behandel gegewe dat die invloeiende CSA nie 15 000 mg/L oorskry nie en dat die regte substraat materiaal gebruik word. Die huidige studie het by die bogenoemde studie aangesluit met die doel om informasie oor die mikrobiologiese kontroles in vleilandsisteme op ‘n toegepaste wyse te voorsien, wat tot verbeterde behandeling doeltreffendheid kan lei. Hierdie studie het verder beoog om by te dra tot ons fundementele kennis van die mikrobiese ekologie van kunsmatige vleilande wat gebruik word vir die behandeling van distilleerafvalwater. Dié studie het bevind dat daar ‘n hoogs dinamiese mikrobiese samestelling binne vleilande bestaan. Daar was verder bevind dat CSA steeds effektief deur vleilande verwyder kan word alhoewel daar ‘n lae graad van ooreenstemming is tussen mikrobiese gemeenskappe in verskeie sones van dieselfde vleiland en verskillende vleilande, asook ‘n lae graad van ooreenstemming tussen gemeenskappe wat in dieselfde sone oor tyd gemonster is. Dit demonstreer dat dit moeilik sal wees om die ‘ideale’ degraderende gemeenskap te vind in terme van mikrobiologiese kriteria en dien as ‘n herinnering dat verkeie indikatore in ag geneem moet word om die welstand van ‘n ekologiese sisteem te monitor. Die verskuiwings in mikrobiese gemeenskapsamestelling illustreer verder die vermoë van natuurlike sisteme om aan te pas by veranderinge in die omgewing sonder om funksionele doeltreffendheid te verminder. Die studie van aangehegte mikobiese gemeenskappe het aangedui dat veskillende morfotipes bespeur kan word tydens sekere fases van biofilm formasie terwyl sekere organismes tydens meeste van die fases teenwoordig is. Die bepaling van CO2 produksie en die verwydering van opgeloste organiese koolstof in laboratoriumskaal kolomme het geïlustreer dat voedende protiste ‘n waarneembare effek gehad op die algehele mikrobiese aktiwiteit en dat die organiese lading hierdie predator-prooi interaksie beïnvloed het. Dit was interessant om te vind dat die teenwoordigheid van protiste die verstopping van porieë aangehelp het en dus tot verlaagde vloei deur die poreuse matriks gelei het. Terminale-restriksie fragment lengte polimorfisme (T-RFLP) analiese van biolfilm op klipgruis in eksperimentele vleilande het aangedui dat die teenwoordigheid van protiste en alge ‘n effek gehad het op die mikrobiese gemeenskapsamestelling. Skandeerelektronmikroskopie (SEM) het bewys dat die teenwoordigheid van alge ook ‘n invloed op biofilm struktuur gehad het wat daarop dui dat alge maklik afbreekbare voedingstowwe aan die bakterieë en giste van die mikrobiese gemeenskap beskikbaar gestel het. Laastens was bewys dat die konsentrasie van toevoeging van ‘n kommersiële mikrobiese mengsel of mikrobiese populasies wat uit afvoer geïsoleer was, die effektiwiteit van degradering kan beïnvloed.