The activated sludge process comprises a complex and enriched culture of a mixture of generalist and specialist organisms. The lack of knowledge on species diversity of microbial communities is due to the simplicity of bacterial morphology and the phenotypic characters, and the unculturable portion of microbial cells in natural habitats. Although a wide range of bacteria can be isolated using conventional microbiological techniques of sample dilution and spread plate inoculation, many well-known activated sludge bacteria can not be isolated using them. The individual microbial cells in activated sludge grow in aggregates that consist of floc-forming organisms together with filamentous microorganisms that form the backbone of the activated sludge floes. Overgrowth of these filamentous microorganisms often causes settling problems called bulking and foaming. These problems consist of slow settling, poor compaction of solids and foam overflow into the effluent. Although methods for the isolation of filamentous bacteria from mixed liquor samples have been investigated, the attempts have been largely unsuccessful. In this study we investigated bulking and foaming activated sludge to identify the dominant filamentous organisms using microscopy and molecular techniques. Using microscopy, the dominant filament associated with the foaming sample was "Microthrix parvicella" and in the bulking sample was Nocardia spp. The foaming sample was investigated using molecular techniques that involved 165 rDNA sequencing. Although some of the clones isolated from the sludge foam were associated with filamentous bacteria causing foam, no positive identification could be made. In the part of the study that was conducted in Australia, a rRNA-targeted oligonucleotide probe was designed for the identification of a filamentous organism occurring in activated sludge foam. This organism resembled Eikelboom Type 0041 and was classified in the candidate bacterial division TM7. The discrepancy that the sequence data did not indicate the dominant filamentous organisms observed by microscopy, highlights the fact that natural microbial communities need to be studied using a combination of techniques since none of the techniques available are sufficient to determine the complete community structure of complex communities such as activated sludge. / Dissertation (MSc (Microbiology))--University of Pretoria, 2005. / Microbiology and Plant Pathology / unrestricted

Submitted in fulfilment of the requirements of the degree of Master of Technology: Biotechnology, Durban University of Technology, Durban, South Africa, 2014. / Wastewater treatment plants (WWTPs) frequently experience bulking and foaming episodes, which present operational challenges by affecting sludge settling due to the excessive proliferation of filamentous bacteria. Various control strategies have been implemented over the years to minimize filamentous growth, however, filamentous bulking still remains an unresolved problem in many WWTPs worldwide. The current study focused on developing and optimizing remedial measures viz., specific and non-specific methods to reduce problematic filamentous bacteria in a full-scale WWTP. Specific methods demonstrated the influence of plant operational parameters viz. chemical oxygen demand, influent N-NH4+, food to microorganism ratio, dissolved oxygen, temperature and pH on the abundance of filamentous bacteria. A cumulative logit model was used to determine the significant relationships between the individual filamentous bacteria at present and the prevailing plant operational parameters. Using the above statistical approach, significant observations and predictions were made with respect to the individual filamentous growth under certain operational parameters. With further validation, this model could be successfully applied to other full-scale WWTPs identifying specific parameters that could contribute to filamentous bulking, thus providing a useful guide for regulating specific filamentous growth. Non-specific control methods such as chlorine, ultraviolet irradiation and ozone treatment were investigated on filamentous bacteria using a live/dead staining technique. To achieve at least 50% reduction of filamentous bacteria, a chlorine dose of 10 mg Cl2/L was required, all filaments were killed at a dose of 22 mg Cl2/L. In addition, an effective UV and ozone dose of 4418.91 μw seconds/cm2 and ±20 mg O3/L respectively, was required to kill 50% of the filamentous bacterial population. Among the three non-specific methods, ozone treatment seemed to be an effective method in controlling the filamentous population with a low negative impact to the surrounding environment. This study serves as a useful guide on the problems and control of filamentous bulking in activated sludge plants. / M

The aim of the thesis is to Mutěnice wastewater treatment plant, which lies in the wine region of Moravia sub-slovácko propose technological measures to the Autumnal wine campaign harboring extreme overload wastewater treatment plant Mutěnice. It will establish a number of options which will be compared with each other.

As the microbrewery industry expands, disposal of brewery wastewater is becoming more of a concern, both for brewery operators and for local municipal wastewater authorities. Brewery wastewater is characterized as containing high strength organics and high variability in both organic and hydraulic loading. This high variability increased the challenge of treating brewery wastewater properly. Therefore, it is significant for optimizing the operation condition for the small-scale wastewater treatment system. This study conducted a batch study and a field study for optimizing a craft brewery on-site wastewater treatment system, which is equipped with two moving bed biofilm reactors (MBBR). In the batch study, a two-factor Box-Wilson central composite design (CCD) was adopted to find optimum biomethane production conditions for the digestion of brewery wastewater with a dairy manure inoculum. The effects of two major influencing factors of temperature (T) (25-49°C) and brewery wastewater concentration (BWC) (2-9 g VS/L) on biochemical methane potential (BMP) (CH₄ yield) and CH₄ maximum production rate (Rmax) were evaluated by applying response surface methodology (RSM). All of the trials presented a high organic removal efficiency with volatile solid (VS) 82-91%, soluble chemical oxygen demand (sCOD) 77-88%, and total chemical oxygen demand (tCOD) between 47% -76%. The experiment result suggested that the first-order kinetic rate constant and biogas content (methane percentage in the biogas) can be affected by the temperature. The mesophilic regime had the highest average rate constant, and the psychrophilic regime rate constant was significantly lower than the mesophilic and thermophile regime. The conditions in the thermophile range present a high variability for the first-order rate constant. The methane ratio in the biogas increased and stabilized by the operation time. Mesophilic and thermophilic regimes obtained a stabile biogas content around 25 days, and the psychrophilic regime spent extra time to stabilized. At the end of the anaerobic digestion, the psychrophilic, mesophilic, and thermophilic regimes had an average methane percentage of 47%,65%, and 67% respectively. Optimum BMP and Rmax were achieved under conditions of 49 °C and BWC of 5g VS/L. Correspondingly, the BMP and Rmax were 141.40 mL CH₄/g VS added and 36.5 mL CH₄/ day, respectively. However, by pursuing stability the preferable operational condition T=35℃ and BWC=5 g/L is recommended, at this condition methane yield is 110.07 CH₄/g VS added and maximum methane daily production is 28.06 CH₄/ day, which is similar to the maximum result. In field study, an on-site brewery wastewater treatment system equipped with two MBBR reactors was evaluated from October 12th, 2018 to February 10th, 2020 in Beau`s All-Natural Brewing Company, Vankleek Hill, Ontario, Canada. The aim of the study was to characterize the wastewater production (flow and organic loading rate), evaluate the operating conditions and performance of the MBBR system, and recommend improvements. Discharge from the brewery is highly variable for both organic and hydraulic loading with flow balancing recommended. The MBBR full-scale reactors operated at relatively stable conditions at a surface area loading rate (SALR) of less than 25 g/m2.d and dissolved oxygen (DO) greater than 2mg/L. Kinetic rate constants for suspended growth and attached growth biomass in the reactors were found to be similar at 0.0764-0.0908 h-1, however, a much larger attached growth mass in the reactors suggests that only a fraction of the attached growth biofilm is active. Effluent recycle was shown to be effective at controlling filamentous bacteria (type-0041) sludge bulking, reducing suspended solid concentration, and sCOD concentration.

Hammarby Sjöstadsverk is a pilot plant operated by IVL Swedish Environmental Research Institute and Royal Institute of Technology (KTH) which treats municipal wastewater. Different processes are used of which one is a Sequential Batch Reactor (SBR) with activated sludge process. The activated sludge process is an effective biological municipal wastewater treatment process. Foaming and floating sludge is a significant problem for municipal wastewater treatment plants globally, that appears from time to time and a full understanding of the process causing this phenomenon is still not available. The problem can have multiple causes such as imbalance of microorganisms, nutrients, toxicity, pH, DO, temperature, denitrification, nitrification etc. The scope of this thesis project is to find out which microorganism’s cause foaming and bulking and how to control it. For this investigation, the Hammarby Sjöstadsverk pilot wastewater treatment plant in Stockholm was utilized. The laboratory facilities at KTH were used during thesis work. Laboratory methods were used to cultivate and isolate filamentous organisms from foam, sludge and inlet wastewater samples to investigate by microscopy and see which microorganisms exist in the activated sludge process were performed. General cultivation media for bacteria and fungi were used for culturing microorganisms. Isolation of some filamentous forms was based on colony morphology on an agar plate and microscopy. Microscopic observation of foam and isolates were performed, comparing cell morphology with literature studies. The sludge showed very few types of protozoa. The isolated and cultivated samples were fungi, yeast-like fungi and bacteria. The organisms are most likely the reason for foaming and bulking. Other reasons were also investigated by comparing retrieved data from IVL with literature studies; the process levels such as pH, DO, temperature and nutrients proved to be low or varying. The reason to why fungi and yeast-like microorganisms habitate in the basin depend on a low pH level average of 6.7. A method for effective settling is to withstand a cutting-pump to the container. This was tested during this project and resulted in increased levels of floating sludge during a period of time. Hence this is not a recommended treatment solution. Suggested treatment methods for further studies are to introduce protozoa to treat foaming and bulking, or by raising the pH and DO. This has not been covered within this project. / Hammarby Sjöstadsverk är en testanläggning som drivs av IVL Svenska Miljöinstitutet och KTH som består av ett avloppsreningsverk i pilotskala. Verket behandlar kommunalt avloppsvatten i en Sekvenserad Batch Reaktor (SBR) med aktiv slam processen. Den aktiva slamprocessen är en effektiv biologisk reningsmetod av avloppsvatten. Skumning och flytslam är ett stort problem för avloppsreningsverk globalt sett. Orsaken till dessa problem kan vara många, som t.ex. obalans av mikroorganismer, näringsämnen, toxicitet, pH, löst syre, temperatur, denitrifikation, nitrifikation osv. Målet med projektet är att ta reda på vilka organismer orsakar skumning och flytslam hos Hammarby Sjöstadsverk i Stockholm. Vad som orsakar dessa samt vilka kontrollmetoder som fungerar mot skumning och flytslam. Under projektet användes laboratoriet på KTH campus för att kultivera och isolera filamentösa organismer för att undersöka dessa under mikroskop och även se vilka mikroorganismer faktiskt existerar i skummet och flytslammet. Ympning av bakterier och fungi användes med hjälp av media. Isolering av vissa filamentösa organismer baserades på dess morfologi på agar plattor. Mikroskopiska observationer av skummet och isoleringar utvärderades och jämfördes med relevant litteratur om cellmorfologi. Resultaten av isolaten var fungi, jäst-liknande fungi och bakterier. Organismerna är mest sannolikt anledningen till skumning och flytslam. Andra anledningar så som datajämförelser med litteraturstudier visade att processens parametrar så som pH, löst syre, temperatur och näringsämnen visades vara låga eller varierande. Anledningen till att exempelvis fungi och jäst-liknande organismer trivdes berodde på låga pH nivåer som i snitt var 6.7. En föreslagen metod för att gynna sedimentering är att inte använda en skärpump till bassängen. Detta testades under projektets gång och resulterade under en period i ökade nivåer av flytslam. Därmed är denna metod inte att föredra. Ett förslag till en biologisk metod introduceras med att tillföra protozoer för att behandla skumning och flytslam, eller att höja pH och löst syre i bassängen. Detta har dock inte undersökts inom ramen för detta projekt.

Nitrogen, when present in excess, can cause eutrophication in waterways, which may result in hypoxia and the desertion or death of aquatic life. As nitrogen continues to pollute our water, wastewater discharge limits are becoming more stringent with effluent limits based on preserving receiving waters. This project took place at the Hampton Roads Sanitation District's, Chesapeake-Elizabeth Wastewater Treatment Plant; a High-Rate Activated Sludge (HRAS) plant with no primary clarifiers operating at an SRT of 1.5" 2 days without biological nitrogen removal (BNR). BNR is considered more cost-effective than comparable chemical and physical processes, but it requires considerable resources to meet increasingly strict discharge limits. As these limits decrease, the resource requirement increases, making them no longer cost-effective. By 2021 HRSD anticipates the plant will be included in a bubble permit, resulting in a total nitrogen (TN) effluent target of approximately 5-8 mg/L. Conventional BNR plants remove carbon and nitrogen simultaneously, which requires both increased volume (capital costs) and aeration energy demand (operating costs). As an alternative, HRSD is pilot testing an A/B process; a two-sludge system comprised of a carbon removal stage followed by a nitrogen removal stage. The very high rate, low dissolved oxygen (DO) A-stage could reduce the organic load, allowing the B-stage to perform BNR within the existing reactor volume and eliminating the need for primary clarifiers. However, improper control of the carbon removal system can lead to carbon and alkalinity deficiencies, which results in poor nitrogen removal. This is mediated by employing a short-cut nitrogen removal technology. A novel aeration strategy based on set-points for reactor ammonia, nitrite and nitrate concentrations with the aim of maintaining equal effluent ammonia and nitrate + nitrite (NOx) concentrations was successfully employed. The goal was to inhibit nitrite-oxidizing bacteria (NOB) so the nitrification process stopped at nitrite. This helps promote an effluent with equal parts ammonia and nitrite, which is amenable to anammox polishing to achieve low effluent nitrogen concentrations. NOB suppression has been successfully applied in sidestream anaerobic digestion waste streams because NOB out-selection is favored in warm, nitrogen-rich conditions. However, the cold, dilute conditions of continuous mainstream processes are not favorable to NOB out-selection. The mechanisms employed to achieve sidestream NOB out-selection are not reasonable for mainstream applications. This study employed operational and process control strategies to aggressively out-select NOB based on optimizing the chemical oxygen demand (COD) input, imposing transient anoxia, aggressive solids retention time (SRT) operation approaching ammonia oxidizing bacteria (AOB) washout, and a dissolved oxygen concentration (DO) of 1.5 mg O2/L during aeration. This pilot-scale study demonstrated that when run aggressively, the proposed online aeration control is able to out-select NOB in mainstream conditions and provide relatively high nitrogen removal without supplemental carbon and alkalinity at a low hydraulic retention time (HRT). Successful full-scale implementation would promote improved water quality that is economically sustainable. The ability of two different process configurations (full intermittent aeration and Modified Ludzak-Ettinger [MLE]) to achieve high nitrite accumulation and nitrogen removal efficiencies in four equal volume tanks in series followed by a cone-bottom clarifier in a pilot scale biological nitrogen removal (BNR) process (V=0.61 m3) was evaluated. All four biological reactors were equipped with a variable speed mixer, a 17.7 cm membrane disc diffuser, and a Hach LDO probe. Aeration capacity in all four tanks allowed the system to be operated with or without a defined anoxic zone. Both processes utilized a novel aeration strategy based on set-points for reactor ammonia, nitrite and nitrate concentrations with the aim of maintaining equal effluent ammonia and NOx concentrations. The B-stage had a variable HRT (2-7 hours) and a variable influent flow rate. When operating in the MLE configuration, an internal mixed liquor recycle (IMLR) line returned nitrified mixed liquor from the last aerobic reactor to the anoxic reactor using a peristaltic pump at a rate between 200-450% of the influent flow. When IMLR was used the first tank was not aerated. RAS from the clarifier was returned to the anoxic zone at 100% of the influent flow. SRT was controlled by wasting solids from the last aerobic tank. The wasting was automated to maintain desired SRT. The nitrite accumulation ratio (NAR), NO2- -N/(NO2- -N+ NO3- -N), was best under full intermittent aeration, achieving 0.43+0.10 at a 3 hour HRT and influent carbon to ammonia ratio (COD/NH4+-N) of 7.9+1.4. As an MLE, the NAR decreased with increasing internal mixed liquor return (IMLR); at IMLR of 200%, 325% and 450%, the NAR was 0.20+0.04, 0.17+0 and 0.14+0.03, respectively. The MLE did, however, improve the overall TIN removal efficiency compared to operation where all reactors were intermittently aerated. The TIN removal efficiency was best under MLE operation, increasing as the IMLR and influent COD/NH4+-N increased. When the IMLR was 200%, 325% and 450%, the TIN removal efficiencies were 76.4+4.0%, 80.2+0% and 86.3+5.0%, respectively, which corresponded to an influent COD/NH4+-N and HRT of 9.2+0.8 and 4 hr, 9.8+0.4 and 6 hr, and 10.3+1.2 and 6 hr, respectively. In addition to process operation, key issues of filamentous bulking were assessed. Concrete solutions to this continual issue are not available as the unique features of each plants influent and process dynamics prohibit the formulation of a universal solution. Filaments observed throughout this study included Type 0041, Type 0675, Type 0803, Nocardia, Thiothrix I and Thiothrix II. Type 0041 and Type 067 were observed throughout the study and are typical of BNR systems; they arguably do not contribute to settling issues. Type 0803 filaments are linked to low F/M, high SRT systems. It was present at the start of the experiment and then no longer detected. Nocardia made a brief appearance on day 72 causing temporary foaming issues. This was fixed by vacuuming the surface of the clarifier daily and may be attributed to the high surface area to volume ratio present in pilot-scale systems. Thiothrix I and Thiothrix II were observed after day 93, however, never as the dominant species. Thiothrix related bulking was observed in the A-stage (Miller et al, 2012), which was attributed to high sulfide and organic acids in the influent raw wastewater during high temperature periods and carryover of sulfide and Thiothrix from the over-sized A-stage clarifier. The goals of this evaluation were to identify favorable parameters of common filaments and establish their impacts on the system. Typically an SVI of 150 mL/g indicates good settling. Overall the study experienced good settling (128.3+36.3 mL/g), indicating that operating under different influent substrate concentrations and process configurations did not result in poor settling. / Master of Science

No description available.

The ability to leach dyestuffs contained in municipal sludge using the Toxicity Characteristic Leaching Procedure (TCLP) was investigated. In addition to the dyestuffs, metals and other organic compounds which also leached were identified. Only small amounts of color were detected in the TCLP extracts; the mean ADMI color values for undigested and aerobically digested sludges were 240 and 156 ADMI color units respectively. Concentrations of individual dyes that may have leached into the TCLP extracts were below detection limits. The reactive vinyl sulfone aniline moiety, which is released as a reduction product from the Remazol dyes used in the cellulosic textile dyeing industry, was found in the leachate from the sludge not treated by extended aerobic digestion. In the leachate from the sludge treated by extended aerobic digestion the reactive vinyl sulfone aniline reduction product was not found, suggesting that this compound was destroyed or rendered immobile by aerobic digestion. Metals leached from the sludge in trace amounts from 0.05 μg/L up to 1 mg/L. Several organic compounds detected in influent wastewater and in leachate from undigested sludge were not found in the leachate from digested sludge. / Master of Science

The activated sludge process efficiency depends on separation of microbial cells from treated wastewater. Separation can fail due to a number of problems. One of these problems is sludge bulking which is non-settling situation of biomass. Former studies showed that phosphorus deficiency caused filamentous sludge bulking with increasing magnesium ion concentrations. The main objectives of this study are to find out the effect of magnesium ions on sludge properties in phosphorus deficient medium and to determine if there is any bulking. Three different concentrations of magnesium (0.5, 5, 15 meq/L) were added to three bioreactors which contained phosphorus deficient medium. In first set C: N: P ratio was 100:5:0.05. In second set, C:N:P ratio was elevated to 100:5:1. At steady state, physical characteristics including sludge volume index (SVI), viscosity, turbidity and dewaterability were determined. Besides concentration of extracellular polymeric substances (EPS) as well as conductivity was measured. By using API kits, bacterial identification was achieved. In first set phosphorus deficiency and increasing magnesium ion concentration caused filamentous bulking. Carbohydrate content of extracellular polymeric substance significantly increased by magnesium addition. Dewaterability of the system got worse and viscosity decreased. Sludge Volume Index (SVI) indicated severe bulking at all magnesium concentrations. By using biochemical tests microorganisms dominant in the system were determined In second set, all of the parameters indicated healthy flocculation. By magnesium addition, EPSp and EPSc increased. Dewaterability and settleability, improved by the presence of phosphorus with close values measured at different magnesiuim concentrations. Nocardia related genera of Corynebacterium and Enteric microorganisms were identified.

Bioflocculation, which can be defined as aggregation of bacterial flocs, has important implications on the physical characteristics of sludge. It is especially critical to settling and dewatering systems which impacts the overall economy of the process greatly. One of the most common problems in activated sludge systems to negatively influence the settleability is sludge bulking which can be defined as non-settling situation of microbial mass. The first objective of this research is to investigate the effect of calcium ion on sludge bulking in a phosphorus deficient medium and the second objective is to improve the settling, dewatering, and pumping of activated sludge by adjusting the calcium (Ca) ion concentration of the feed. For this purpose, 7 semi-continuous laboratory scale activated sludge reactors were operated with a mixed aerobic culture. The reactors had 8 days of sludge residence time and aerated with air pumps to provide a dissolved oxygen concentration of at least 3 mg/L. All the analyses were conducted after the reactors reached steady state condition. In the first part of the research, the effect of strictly phosphorus-limited medium on bulking of activated sludge was studied at different calcium ion concentration. Three reactors were set up having 5, 10 and 20 meq/L calcium concentrations. From the results it was observed that, phosphorus deficiency caused viscous bulking independent from the calcium ion concentration. It was found out that bulking of activated sludges due to phosphorus deficiency could be cured by the addition of phosphorus. Furhermore, microorganisms starved for phosphorus, seemed to accumulate polyphosphate granules when they were exposed to a phosphorus source. In the second part of the study, the effect of calcium ion on physical, chemical and surface chemical properties of activated sludge was investigated at 4 different concentrations (0.27, 5, 10 and 20 meq/L) under sufficient phosphorus concentration. Calcium addition resulted in significant changes in the quantity and quality of extracellular polymeric substances (EPS). Total EPS increased depending on the calcium concentration. Carbohydrate content of EPS dominated over the protein content for calcium concentration of 5 meq/L and above. The amount of calcium ions incorporated into the sludge floc matrix also increased with the dose of calcium added. Settleability and dewaterability of sludge improved significantly at 5 meq/L dose of calcium. However, settleability did not change any further with increasing calcium dose, whereas dewaterability increased for all increasing calcium concentrations. Sludge viscosity also decreased considerably at 5 meq/L concentration indicating better pumpability but it did not change further above 10 meq/L calcium addition.