published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

8 pp. / The land application (non-hazardous sewage sludge) biosolids has been in practice in Arizona since the 60s.

Su veikliojo dumblo suspensijomis, gautomis iš Vilniaus miesto, Nemenčinės ir Utenos miesto nuotekų valyklų buvo vykdomi tyrimai, kuriais siekta ištirti nuotekose esančių teršalų poveikį veikliojo dumblo mikroorganizmams ir nustatyti indikatorines rūšis šio poveikio įvertinimui. Tyrimai atlikti su šiais teršalais: 3,5 – dichlorfenoliu (3,5 – DCP), etanoliu ir valgomąja druska (NaCl). Veikliojo dumblo suspensijos buvo analizuojamos mikrobiologiškai, skaičiuojami mikroorganizmų rūšys ir individų skaičius (ind./ml). Per tyrimą buvo atlikta 16 eksperimentų ir nustatytos mikrobiologinė nuotekų valyklų sudėtys, iš kurių buvo gautos veikliojo dumblo suspensijos. Buvo įvertinti teršalų poveikiai veikliojo dumblo mikroorganizmų bendrijoms. Prie mažų (2,5 ppm, 5 ppm ir 7,5 ppm) 3,5 – DCP koncentracijų veikliojo dumblo mikroorganizmai adaptavosi, o didelės (15 ppm ir 20 ppm) koncentracijos naikina veikliojo dumblo mikroorganizmus. Etanolis veikliojo dumblo mikroorganizmų bendrijas veikia skatinančiai, kadangi auga veikliojo dumblo koncentracija ir bakterijų monokolonijų skaičius. Mažos (3 g/l, 5 g/l ir 7 g/l) NaCl koncentracijos skatina veikliojo dumblo mikroorganizmų bendrijas, prie 10 g/l dumblo organizmai adaptuojasi, o prie didelės (15 g/l) NaCl koncentracijos mikroorganizmų skaičius mažėjo. Taip pat nustatytos jautriausios mikroorganizmų rūšys (Acineria uncinata, Aspidisca costata, A. lynceus, Vorticella spp., Ptelomonas sp., plikosios amebos ir bakterijos, sudarančios... [toliau žr. visą tekstą] / The investigations of active sludge taken from Vilnius, Utena and Nemenčinė wastewater treatment plants was carries out. The main goal was investigate the effects of wastewater pollutants on communities of microorganisms taken from activated sludge and to identify indicator species of this impact assessment. Investigations were carried out with these pollutants: 3,5 - dichlorophenol (3,5 - DCP), ethanol, and salt (NaCl). Active sludge was analyzed microbiologically, number of species and number of individuals (ind. / ml) were counted. In this study 16 experiments was carried out and microbiological composition of wastewater treatment plants was estimated. Results showed that activated sludge microorganisms adapted to low (2.5 ppm, 5 ppm and 7.5 ppm) concentrations of 3,5 – DCP, but high (15 ppm and 20 ppm) concentrations reduced abundance of microorganisms. Ethanol stimulated community of activated sludge, because concentration of activated sludge and number of bacterial colonies increased. Low concentrations (3 g/l, 5 g/l ir 7 g/l) of NaCl also stimulated abundance of active sludge community, microorganisms adapted to the concentration of 10 g/l, and number of microorganisms decreased when concentration of NaCl was high (15 g/ l). Acineria uncinata, Aspidisca costata, A. lynceus, Vorticella spp., Ptelomonas sp., gymnamoebae and bacteria (which makes clusters) – this was the most sensitive species of microorganism in activated sludge. A. costata resisted quite high (even 10... [to full text]

HT biomass sonicated at ES inputs < 56KJ/gTS decreased floc size by 41% and enhanced its metabolic activity by 50-250% compared to control. ES inputs >118 KJ/gTS caused HT biomass solubilization and irreversible loss of its metabolic activity and reflocculation ability. During continuous activated sludge processing (ASP) of real primary effluent the observed yield (Yobs) decreased by 20% compared to control ASP at SF (stress factor) of 1 (biomass exchanged without USPT). At SF of 0.5, 1 and 1.5 (biomass exchanged with USPT) the Yobs further decreased by 33, 25 and 44% respectively as compared to control. This indicated that combining biomass anoxic exposure with USPT enhanced sludge reduction by increasing microbial maintenance metabolism likely in combination with microbial flora shift in the ASP depending on SF.

Wastewater sludge is considered a valuable source of nutrients and energy. Freeze/thaw treatment is an efficient dewatering method for wastewater sludge management in First Nation communities located in cold climate conditions. Natural freeze/thaw is a simple, practical and low cost method, which can effectively dewater sludge. The objective of this research is to evaluate dewatering, nutrient recovery and organics separation of wastewater sludge originating from different wastewater treatment processes using freeze/thaw processing. The results of experiments showed the effectiveness of this method in sludge dewaterability and solubilisation of organics and nutrients. The sludge solid content increased by approximately 10-fold after treatment. It was effective in solubilisation of about 15.2%, 33.5% and 21.5% of total nitrogen, total phosphorus and total chemical oxygen demand to soluble one, respectively for the non-BNR sludge. However, anaerobic digestion of the solid cake post freeze/thaw treatment did not show enhanced methane yield compared with fresh sludge. / February 2017

The treatment of synthetic landfill leachate and raw landfill leachate were investigated using two sets of 3 L aerobic sequencing batch reactors (SBR): activated sludge SBR (ASBR) and granular SBR (GSBR). In synthetic young landfill leachate treatment, GSBR was more efficient in nitrogen and carbon removal than ASBR. During the steady period of the experiment, 99% total ammonium nitrogen (TAN) was removed through nitritation and nitrification in GSBR with an average influent TAN concentration of 498 mg/L. On the contrary, complete nitrification was not achieved in ASBR with a nitrification efficiency of 77±10%. GSBR also presented higher efficiency in denitrification and COD removal compared to ASBR. Phosphorus removal efficiency was almost identical in both reactors. Synthetic old landfill leachate treatment using GSBR maintained the stable COD removal efficiency at 66%, when the ammonia nitrogen to the maximum of 465±46 mg/L. The ASBR required a start-up of at least 30 days and removed 59±9% of COD when an influent ammonia nitrogen concentration about 200 mg/L. The GSBR was also more efficient than the ASBR for nitrogen removal. The granular sludge reached a maximum ammonia removal of 95±7%, whereas 96±5% was achieved by ASBR. The phosphorus removal was likely affected by the free nitrous acid (FNA) and the low biodegradability of tannic acid. In raw landfill leachate treatment, the total ammonia nitrogen (TAN) removal efficiency was in GSBR approximately 99.7%. However, the ASBR treatment did not show a consistent performance in TAN removal. TAN removal efficiency decreased with increasing ammonia concentration in the influent. Nitrification in GSBR was partially inhibited at FA concentrations of 48 to 57 mg/L, which was two times more than the FA concentration that inhibited nitrification in ASBR. In terms of chemical oxygen demand (COD) removal, low removal efficiencies of 17% and 26% were observed in ASBR and GSBR, respectively. The low COD removal efficiencies were associated with the refractory organic content of the leachate used in this study, which resulted in a poor phosphorous removal performance as well. Overall, aerobic granular sludge showed a better performance in removing nutrients and organic matter from young or old landfill leachate, being more efficient than the conventional suspended growth activated sludge. Therefore, the use of AGS for leachate treatment should be encouraged. Further investigations should also be addressed, especially with a focus on improving SND and phosphorus removal efficiencies. / May 2017

Dissertation submitted in compliance with the requirements for the Master's Degree in Technology: Biotechnology, Technikon Natal, 2001. / Up until now extensive work has been done to develop kinetic models and related software that can be used successfully to simulate and design nitrification denitrification (ND) and nitrification denitrification biological excess phosphorus removal (NDBEPR) systems for efficient nitrogen removal. The denitrification kinetics of these systems have primarily been determined and attributed to the ordinary heterotrophic bacteria, now also known as the OHO fraction, otherwise not involved in biological excess phosphorus removal. However, denitrification kinetics determined for ND systems have been found to vary considerably at times when applied to NDBEPR systems because of varying OHO active fraction estimates and the unexplained occurrence of anoxic phosphorus removal and anysuccess achieved to date has been some what fortuitous. Ultimately variations in process performance and kinetics are attributable to inadequate control and lack of understanding of the ecological, physiological and biochemical activities of constituent microorganisms. There is growing concern and movement towards a better understanding of the microbial community within activated sludge in order to gain optimal control of the process. / M

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 activated sludge process is one of the most commonly employed domestic and industrial waste treatment process. Different types of mathematical models have been proposed for design and operation of this process, most of which do not consider the relationship between the sludge settling characteristics and the aeration unit performance. This project studies the validity of a model developed by La Motta (2004b) which links the operating parameters of an activated sludge system and the classical limiting flux sludge settling theory. Favorable results were obtained demonstrating that the model predicts very similar values of the parameters of the system in comparison with the parameters observed in an activated sludge pilot plant that is located within installations of the Marrero Wastewater Treatment Plant, New Orleans, Louisiana. This research also demonstrated that the model is a helpful tool for the design and operation of an activated sludge system.

Aerobic activated sludge membrane bioreactors (AS-MBR) in municipal wastewater treatment are compact systems that can efficiently perform biological organic oxidation. However, aerobic processes require mechanical aeration accounting for over 40% of total expenditure of a wastewater facility. Additionally, a global urgency for nutrient (Nitrogen/Phosphorus) removal strategies due to surges of eutrophication events requires complex MBR configurations. An innovative and cost-effective process was developed with a dual income-stream: high-quality treated effluent and value-added microalgal biomass for several applications. The proposed process involved several integrated components; an ultrafiltration AS-MBR for organic oxidation followed by a microalgal membrane photobioreactor (MPBR) to remove nutrients (N/P) through assimilation while simultaneously photosynthetically generating dissolved oxygen effluent that was recirculated back into the AS-MBR, thereby reducing the need for mechanical aeration for oxidation. A lab-scale system was fed with a synthetic medium-strength municipal wastewater. The microalgal species C. vulgaris was initially tested in batch trials as a proof-of-concept study on its potential as a photosynthetic oxygenator for the AS-MBR and identify its nutrient utilization efficiencies. The MPBR and MBR were later constructed for continuous operation, with the aim to identify an optimal process configuration. The unit processes were subsequently isolated, where the AS-MBR was subjected to a modelled algal effluent to assesses the impact of varying influent characteristics and effluent recycle rates. A microbial community analysis was performed by high-throughput sequencing and a statistical data-driven modeling approach to assess treatment performances. The MPBR stage was then subjected to the effluent achieved by the AS-MBR stage under varying operating conditions to assess its treatment performance and the resulting algal biomass biochemical composition to identify its suitability for bioethanol, biodiesel, or animal feed production. The findings of this study ultimately confirmed the ability of C. vulgaris to support the AS-MBR for organic removal and fractional nutrient removal by supplying the oxygen demand, and further achieve an effluent polish stage for nutrient removal. The process configuration also demonstrated the ability to achieve a high microalgal biomass production with the potential of extracting valuable products as an added benefit of the wastewater treatment.