Στη συγκεκριμένη εργασία μελετήθηκαν οι φυσικοχημικές παράμετροι που επιδρούν στη ποιότητα των υδάτων της λιμνοθάλασσας, διαταράσσοντας την ισορροπία του οικοσυστήματος, προκειμένου να αποκαλυφθούν οι πιθανές περιβαλλοντικές επιπτώσεις που δημιουργούνται σε αυτό, από τις κλιματικές αλλαγές που επικρατούν στη περιοχή. / The Kotychi lagoon is located in the north-west of Peloponnese and constitutes a very significant ecologic heritage not only for the particular area but also for Greece in general. The great ecologic and economic value that characterises the lagoon and the wetland habitat around it has been acknowledged under international treaties (RAMSAR), European programs for the protection of the nature (NATURA 2000) and its bio-diversity while jointly there is an intense interest for its conservation and protection. In this particular research, the physiochemical parameters that affect the quality of the water of the lagoon were considered, by deranging the balance of the ecosystem having as a purpose to detect the presumable environmental reverberations that have been occurred due to climatic changes that affected the area. The temperature of the water of the lagoon follows a natural daily fluctuation. The lowest average temperatures of the water are recorded during the winter, whereas the highest average temperatures are recorded during the summer. The specific conductivity of the water shows significant fluctuation which is created by the entry-exit process of the marine and fresh water in the lagoon. The figures of the solution oxygen present a significant daily fluctuation that follows accordingly all the fluctuations of the temperature of the water, also fluctuate in normal rates and they do not alienate the pisci-fauna. The PH rate of the water presents a natural daily fluctuation of a 0.5 rate which is proportional to the temperature and the concentration of the solution oxygen. The water of the lagoon can be characterised as properly clear. The average levels of the chlorophyll for all the duration of the research period have been quite low, which is a case that shows that the lagoon does not show any important problems of eutrophy from photosynthetic organisms.

Salinisation has been identified as a major cause of the progressive deterioration in the public water system in South Africa. To deal with this problem Waste Stabilisation Ponding systems have been used by the Leather Processing Industry as zero-dischaJ;ge wastewater evaporation disposal processes in water-limited inland regions of the country. While effective in the evaporation disposal function these systems are plagued by the generation of serious odour nuisance creating intractable environmental problems relating to adjacent residential communities. High loading to ponds of organic compounds, sulphides and ammonia results in strongly reducing anaerobic conditions prevailing in early parts of pond cascades. These are characterised by bright red colours due to the predominance of purple photosynthetic bacteria. Sporadic micro algal blooms of Spirulina sp. and Dunaliella sp. had been previously noted to occur on the latter ponds in these cascades, and were associated with their conversion to facultative function, with aerobic surface layers, and a marked reduction in odour release. This research programme undertook an investigation of the microbial ecology of a tannery waste stabilisation ponding system to describe factors which give rise to these blooms, and to determine whether microalgal growth may be manipulated to achieve a reliable oxygengenerating capping of the anaerobic ponds. The predominance of near pure cultures of Spin/lina platensis was demonstrated for the blooms and factors restricting its growth in the system were described. These include the interaction of ammonia and sulphide toxic effects and laboratory studies were undertaken to show how effluent loading may be regulated to enable effective growth of the cyanobacterium. At appropriate dilutions of tannery effluent an enhancement of growth was noted, compared to growth in defined mineral medium. An investigation of this phenomenon provided preliminary evidence for organic uptake by the pond micro algae and a possible contribution to heterotrophic nutrition. The manipulation of Spirulina sp. growth in a High Rate Algal Pond raceway was undertaken in outdoor pilot plant studies and the effect of microalgal capping of the anaerobic ponds in the cascade was demonstrated by activating a recycle loop from a blooming facultative pond. Heavy metal contaminants were effectively eliminated by an optimisation of the primary anaerobic pond function and precipitation as metal sulphides. Biomass was harvested and dried, during which a range of methods were evaluated. Toxicological studies were undertaken on the dried biomass using Artemia and chick assays, and feed studies showed its useful application in rations for the abalone Haliotlls midae and rainbow trout Onchorhynchlls mykiss. Based on positive independent assessment of research outcomes, a decision was made by the tanning company operating the Waste Stabilisation Ponding system, to proceed to the construction of a full-scale 2 500 m2 High Rate Algal Pond raceway. This would be used for controlled Spirlilina biomass production to effect a practical capping of the anaerobic ponds in the system, and to evaluate its commercial potential in the feed market. The Advanced Integrated Wastewater Ponding System described by Oswald (1991) provided the conceptual basis for the Algal Biotechnology process development undertaken. The studies of the microbial ecology and the biotechnological potential of this system have shown that a Spirulina-based High Rate Algal Ponding process can be engineered in such a way that saline tannery effluents may be treated to effect a significant reduction in overall pollution load, that biomass may be recovered as a value added product of the treatment process and that the operational performance of Waste Stabilisation Ponding systems, and hence their immediate environment, may be improved by the use of the High Rate Algal Pond as a retrofitted upgrading unit operation.

No description available.

A waste stabilization pond was investigated to determine if there was a health hazard due to contamination of the shore line. Soil samples were taken at various points along the bank and water samples were collected from the pond. Coliform and enterococci counts were made from the samples and were employed in conjunction with observations made of conditions at the sample points to determine if a health hazard existed at the shore line. Three stations were located along the leeward side of the pond. At each station samples were taken in adjacent soil, soil at the water line, water at the water line, water from the pond surface and water from one and one-half feet beneath the pond surface off shore. Using the geometric mean, coliform counts ranked as follows: 1717.7 water sample one and one-half feet below the surface and off shore, 583.9 soil sample at the water line, 79.0 soil on adjacent bank, 20.2 surface water sample off shore, and 11.5 water sample at water line. The high count one and one-half feet below the surface is presumably from the sewage being added to the pond. Low counts were associated with pH values near ten. High counts generally occurred at more neutral pH values of about eight. The counts at the water line are not high enough to indicate the presence of significant concentrations of fecal matter. Also, no fecal matter or other floating matter was observed at the shore line. The counts from the soil on the bank up from the shore line were what would be expected from a similar area excluding the waste stabilization pond. A comparison of the coliform and enterococci counts showed that the enterococci count is approximately one half the coliform count which is in agreement with other investigations (2) and indicates its usefulness as an indicator organism. / Master of Science

Thesis (Ph. D.)--University of Texas at Austin, 1995. / Vita. Includes bibliographical references (leaves 287-313).

No description available.

Energy demand, greenhouse gas emissions, and operational costs are continuing to rise year on year in the wastewater treatment sector, with traditional treatment options unable to provide sustainable solutions to increasing volumes and tightening quality standards. Current processes produce inherent fugitive greenhouse gas (GHG) emissions, whilst also generating large quantities of sludge for disposal. Anaerobic ponds (APs) are natural wastewater treatment processes that have traditionally been confined to a pre-treatment stage of larger stabilisation pond systems. Consequently, current standard guidelines are not suited for low temperature, weak strength wastewaters, or for the emerging usage of APs for energy recovery and enhanced organic breakdown. To establish effective guidelines for adapting AP design for this purpose, this thesis explores the fundamental mechanisms with APs, in order to provide design alterations to enhance AP performance for full flow domestic wastewater treatment with a focus on the UK water sector. Initially, a literature review of current AP design guidelines was conducted to determine the current state of the art and understand the fundamental design processes currently adopted. The review found that most APs are currently underloaded, largely to avoid malodour emissions, but this leads to unnecessarily large footprints and inhibits the digestion process through restricting biomass/substrate contact. It was concluded that the current design guidelines are not suitable for recent AP developments and application, such as covering to prevent odour escape, and the use of baffling to improve mixing and enhance organic degradation. A pilot scale study was conducted on UK domestic wastewater to gain insight into the limitations of current AP design for this application and identify areas for optimisation. The pilot trial demonstrated the efficacy of AP usage for low temperature, weak strength wastewaters, even with unoptimised design. Decoupling hydraulic and solids retention time lead to biomass retention and subsequent acclimatisation, and was able to compensate for the low temperatures and weak wastewater. It was concluded that APs can provide an attractive alternative to current primary treatment options, through reducing GHG emissions and providing less frequent desludging requirements. To optimise AP design, the effect of baffle configuration on AP hydrodynamics and the subsequent impact on treatment efficiency was investigated, in order to develop structural designs specifically targeting enhanced anaerobic degradation. Advantages found in baffling APs included improving mixing patterns between baffles, enhancing biomass/substrate contact, and creating an overall plug flow effect through the entire pond enabling the retention of biomass. Furthermore, the removal mechanism with the pond can be manipulated with use of baffles, with different orientations generating different flow patterns and therefore creating conditions preferential for greater solids settlement and capture, or mixing and contact. Following trials on single stage alternate baffling configurations, the development of a novel two stage AP design was trialled, applying knowledge gained from trials of differing baffle orientations to target separate stages of organic breakdown. Further trials were conducted on the staged AP to establish optimal loading rates to be applied to APs in order to maximise performance and reduce physical footprint. These trials led to recommended design improvements including shorter hydraulic retention times (HRTs) to enhance mixing and decrease physical footprint, and improvements to the staged AP design to greater separate the stages of anaerobic digestion and provide optimal conditions for the stages at different points in the AP. Finally, the knowledge gained from experimental work was used to present evidence for the inclusion of APs into decentralised WWT through flowsheet modelling of a proposed AP treatment works compared to a current base case. Advantages were found in decreasing sludge management requirements whilst providing suitable primary treatment, with additional potential benefits in renewable energy generation, which could increase both with improved biogas yields and the option of combining with other renewable technologies. In some circumstances, it may be possible for an AP flowsheet to operate entirely off-grid, eliminating the need for costly infrastructure such as permanent access roads and national electrical grid connection.

The transesterification of lipids extracted from algae makes up the third generation of biodiesel production. The city of Logan, Utah, proposes that the algae used from the 460-acre wastewater pond could potentially be used for the production of biofuel that could serve as transportation fuel for the City solid waste vehicles. Separating the algae from the Logan Lagoon wastewater is the most expensive portion of the biodiesel process and the application of chemical flocculation can significantly increase costs and potentially interfere with biodiesel production. Cross flow filtration has been identified for algae harvesting, and experiments were conducted to evaluate materials and operating conditions for separating and harvesting algae from the Logan Lagoon system. Two cross flow filtrations units were used to conduct experiments. A pilot-scale cross flow filtration unit provided by WesTech, Inc., Engineering (Salt Lake City) with a 0.2-micron nylon membrane mesh was used for mixed-culture algae harvesting. In addition, a bench scale cross flow filtration unit was provided, and tests were conducted to further examine the effectiveness of cross flow filtration on pure-culture algae harvesting. A 1-micron nylon, 5-micron nylon and 5-micron polyester mesh were used with this system. The WesTech, Inc., Pilot Scale System demonstrated that the type of membrane used was critical for effective algae harvesting. Test results showed that the algal cake that developed on the membrane and that the amount of algae harvested decreased with flux. The bench scale unit demonstrated that more algal cells were collected when a membrane of a larger pore size was used. The 1-micron nylon mesh proved to be the most effective at concentration algae. The 5-micron polyester mesh was shown to be more effective than the 5-micron nylon mesh. The results in this thesis show that cross flow filtration is a feasible option for the City of Logan Environmental Department and is a technical option for algal harvesting for biofuel production.

Investigates several hypotheses regarding the use of bioflocculation as a harvesting method for wastewater pond microalgae. Research performed on pilot-scale high rate ponds (HRPs) on the California Central Coast.

Extreme hunger, malnutrition, and the lack of access to sanitation are among the most pressing development challenges, but the world is not on track to meet the targets that have been established by the Millennium Development Goals. The integration of wastewater treatment and food production systems allows for the recovery of resources from wastewater, and can provide an important solution to meet the sanitation needs of growing urban populations and provide periurban farmers with a consistent supply of water and nutrients. Stabilization ponds have been long considered to be an appropriate technology for wastewater reuse systems in developing countries, but advanced anaerobic treatment technologies, such as upflow anaerobic sludge blanket (UASB) reactors, are also becoming common. The objective of this study is to evaluate the reuse potential of wastewater for irrigation from two community-managed treatment systems in Bolivia: one consisting of three stabilization ponds in series (three-pond system) and the other consisting of a UASB reactor and two stabilization ponds in series (UASB-pond system). Specifically, the removal of helminth eggs and thermotolerant coliform bacteria is measured in both systems and evaluated with respect to the World Health Organization (WHO) guidelines for the safe use of wastewater in agriculture, which are based on health targets. Results indicate that both systems provide good removal of conventional water quality parameters but poor removal of nutrients, discharging effluents with 37 to 54 mg/L of total nitrogen and 5.7 to 9.4 mg/L of total phosphorus. The three-pond system provided >92% removal of helminth eggs and 3.4-log removal of thermotolerant coliforms, and no geohelminth eggs were detected in the system effluents. However, Ascaris eggs were detected in the effluents of the UASB-pond system and the overall removal of thermotolerant coliforms was only 2.3 log units. Viability estimates based on the use of a vital stain indicate that eggs detected in pond effluents are less likely to be viable than eggs detected in the raw wastewater, in the sludge, or in the effluent of the UASB reactor. Sludge samples from the facultative pond in the three-pond system had higher concentrations of helminth eggs than sludge samples from the UASB reactor. Based on these results, the effluents from the three-pond system can be reused for irrigating any crop with the exception of root crops and low-growing crops that can be consumed raw (i.e. onions and strawberries). Effluents from the three-pond system may be used to irrigate salad crops or high-growing crops that are consumed raw, but additional public health interventions must be implemented throughout the food production process to meet WHO recommendations for protecting the health of farmers and consumers. The effluents from the UASB-pond system should not be reused unless improvements to the system increase its pathogen removal efficiency. The results from this study indicate that a system consisting of stabilization ponds in series may produce a higher quality effluent that is more suitable for wastewater irrigation than a system with a UASB reactor.