Kitchen waste is the certain man-made trash in our daily life. It is mainly the water and oil, which is easy to decompose. In Taiwan, there is about 20,000 metric tons of family rubbish everyday, and approximately 20% to 30% of the rubbish is organic substance. Moreover, kitchen waste has a significant contribution on the total amount of rubbish. Thus, reduction and recycling of kitchen waste becomes an important issue, and it needs to be solved immediately. According to the article of Water Pollutant Prevention Act revised by Environmental Protection Bureau on 26 April 2000, wastewater discharges from apartment buildings need to be treated to meet the discharge standards. Furthermore, the discharge standards will be even more stringent in the near future. Kitchen wastewater includes liquids of kitchen rubbish, liquid of waste oil, and wastewater from grinding machines for food waste crushing. If all of the above polluting wastewater is discharged directly to the sewer system, the cost for sewer system maintenance would be huge. To protect the ecosystem and to minimize the cost of sewer system maintenance, kitchen waste and its wastewater need to be effectively treated. In this study, a kitchen waste treatment system is designed and constructed. This system is able to treat kitchen wastewater efficiently and effectively. Moreover, this system is easy to operate and maintain with less maintenance cost. The treated wastewater could meet the discharge standards with 91.4% of suspended solid removal, 91% of chemical oxygen demand (COD) removal, 96.7% of biochemical oxygen demand (BOD) removal, and 100% of grease removal.

Phosphorus (P) is a pollutant in freshwater systems because it promotes eutrophication. The dairies in the North Bosque and its water body segments import more P than they export. Dairies accumulate P-rich effluent in lagoons and use the wastewater for irrigation. As more P is applied as irrigation than is removed by crops, P accumulates in the soil. During intense rainfall events, P enters the river with stormwater runoff and can become bio-available. Reducing the P applied to the land would limit P build up in the soil and reduce the potential for P pollution. Since wastewater P is associated with suspended solids (SS), the flocculants, poly-DADMAC and PAM, were used to reduce SS. To precipitate soluble P from the effluent, NH4OH was added to raise the pH. Raw effluent was collected from a dairy in Comanche County, TX, and stored in 190-L barrels in a laboratory at Texas A&M University. Flocculant additions reduced effluent P content by as much as 66%. Addition of NH4OH to the flocculated effluent raised the pH from near 8 to near 9, inducing P precipitation, further reducing the P content. The total P reduction for the best combination of treatments was 97%, a decrease from 76 to 2 mg L-1. If this level of reduction were achieved in dairy operations, P pollution from effluent application would gradually disappear.

The frequency of on-site systems for treatment of domestic wastewater is increasing with new residential development in both rural and low-density suburban areas. Subsurface flow constructed wetlands (SFCW) have emerged as a viable option to achieve advanced or secondary treatment of domestic wastewater. The pollutant removal efficiency in SFCW depends on design parameters. Many of these factors have been investigated while others such as aspect ratio, design of water inlet structure and method of dosing the wetland have yet to be fully examined. This study examined the effect of aspect ratio and header design on BOD5 removal efficiency as well as the impact of flow rate on flow distribution in a SFCW. An aspect ratio of 4:1 achieved 10% greater removal of organic matter than a 1:1 ratio. Tracer studies demonstrated that wetlands loaded at a constant rate of 3.8 L/min and 7.6 L/min experienced preferential flow. In addition, tracer studies showed wetlands with leaching chambers as headers failed to achieve equal flow distribution. An improvement in effluent water quality was achieved by replacing the leaching chamber for a perforated manifold as the inlet structure. This study demonstrated the importance of the careful selection of aspect ratio and means by which water is introduced to the wetland in the design of SFCW.

High rate algal ponds (HRAPs) are an advanced pond that provide efficient and cost-effective wastewater treatment, as well as the ability to recover nutrients in the form of microalgal biomass. Microalgal photosynthesis, nutrient uptake and subsequent growth, coupled with aerobic bacteria degradation of organic compounds, are fundamental to the process of wastewater treatment in HRAPs, yet are often limited in these ponds and, in particular, microalgal photosynthesis is well below the reported theoretical maximum. Understanding how the physico-chemical environment affects microalgal performance is therefore critical to improved wastewater treatment and nutrient recovery, yet has been the subject to few studies to date. This research focused on the enhancement of microalgal photo-physiology, growth and nutrient removal efficiency (NRE) through modification to the physical and chemical environment in wastewater HRAPs. In this study, I first examined the seasonal dynamics of microalgal performance in full-scale wastewater HRAPs. While both retention-time corrected chlorophyll biomass and photosynthetic potential increased from winter to summer, the summer-time performance was considered to be constrained, as indicated by the decreased light absorption, light conversion efficiency and NRE. The physico-chemical environment in the full-scale HRAPs were characterised by high day-time pH, high light attenuation and long, straight channels with low turbulence. This led to questions regarding 1) effects of nutrient supply, in particular carbon and 2) the role of the HRAP light climate on microalgal performance. I addressed these questions using a series of experiments that involved either changing the nutrient concentration and its supply or by modifying the light environment, through changes in pond operational parameters including CO2 addition, influent dilution, pond depth, hydraulic retention time (HRT), mixing speed and frequency. The overall results from these experiments showed that carbon was the primary and light the secondary limiting factors of microalgal performance. These limitations negatively affected light absorption, photosynthesis, productivity and NRE. While each operational parameter tested impacted on microalgal performance, to some degree, CO2 addition had the greatest influence on light absorption, photosynthetic efficiency and productivity, while continuous mixing had the greatest effect on NRE. Adding CO2 increased light absorption by 110% and 128%, maximum rate of photosynthesis by 185% and 218% and microalgal biovolume by between 150 – 256% and 260 – 660% (species specific), when cultures were maintained at pH 8 and 6.5, respectively. Providing sufficient mixing to achieve continuous turbulence enhanced NRE by between 300 – 425% (species specific), increased biomass concentrations between 150% and 4000% (species specific) compared to intermittent and no mixing, respectively, and increased harvest-ability of colonial species. However, at present, both CO2 addition and mechanical mixing attract high capital and operational costs. Modification to these technologies would be required to meet the objectives of cost-effective wastewater treatment and biofuel production. A more immediate and cost-effective solution demonstrated in this study was the altering pond depth, influent concentration and HRT. Doubling pond depth from 200 to 400 mm increased both microalgal nutrient removal and photosynthetic efficiencies which led to areal productivity increasing by up to 200%. When increased pond depth was coupled with decreased HRT, light absorption and photosynthetic performance further increased due to decreased internal self-shading and improved pond light climate. For nutrients, high influent loads increased productivity, while moderate loads increased effluent water quality. Overall, this work demonstrated that optimising the chemical and physical environment of wastewater treatment HRAPs (CO2 addition to maintain pH at 6.5 – 7, 400 mm pond depth, continuous mixing with vertical speed of 200 mm s-1, moderate nutrient load (15- 30 g m-3) and moderate HRT (4 / 6 days summer / autumn) can enhance microalgal biomass productivity, nutrient recovery as well as improve effluent water quality, particularly during summer when growth can be constrained.

The self-treatment system of nature cannot handle man-caused high rate water pollution on its own, therefore cleaning in wastewater treatment plant (WWTP) is necessary to avoid eutrophication – excessive enrichment of nature by nutrients. Current technologies applied in WWTPs are old, outdating and highly energy demanding, especially biological treatment step generally requires large amount of energy for aeration of water. The alternative to current system could be microalgae treatment step, which would use green algae to consume pollutants present in the waste water, namely nitrogen, phosphorus and heavy metals. Via photosynthesis it could produce oxygen required for biological oxidation of organic matter. Furthermore carbon source is necessary for microalgal growth, this can be added to the water as CO2 produced in other industries and so decrease global greenhouse gas footprint. Co-digestion of microalgae with undigested wastewater sludge under mesophilic conditions can give a synergic effect for biogas production, therefore harvested and co-digested microalgae could contribute to positive energy balance of WWTP. Full-scale microalgae cultivation in WWTP can be achieved only when good grow is guaranteed. This is a result of many factors, particularly access to nutrients, light condition, water temperature, and pH. The goal of master’s thesis was to understand and evaluate main factors influencing algal growth using literature review, propose design of microalgae treatment step with artificial lights and evaluate energy balance, of wastewater treatment plants in Uppsala and Västerås with new design. The work proposed two different designs of microalgae treatment steps, modelled in Excel and applied to current state of municipal WWTP in Västerås and Uppsala with belonging satellite plants. The first design of microalgae activated photobioreactor (MAASPBR) aimed to replace current biological treatment step. This is possible in Västerås and Uppsala WWTPs if microalgae can consume 75% of total nitrogen (Ntot) and produce at least 13.5 and 2.4 tonne O2/day in Västerås and Uppsala respectively. The sensitivity analysis showed that minimal volumetric algal yield of 0.15 kg/m3 ,day and 0.25 kg/m3 ,day is required for Västerås and Uppsala respectively, when oxygen production rate of 1.92 kg O2/kg microalgae is assumed. Furthermore harvested and co-digested algae with sewage sludge contributes to significant increase of biogas production and negligible transportation energy increase. The second design of open algal pond for reject water (OAPRW) aims to cultivate microalgae on reject water with high concentration of nutrients, generated in sludge centrifuge. The model assumed high algal growth due to excessive amount of nutrients and increased water temperature to 24°C. Results show a possible 23% and 20% electricity saving on blowers in the biological treatment in Västerås and Uppsala respectively. Both models have positive impact on energy balance in all WWTPs, however MAASPBR has greater uncertainties, because this type of photobioreactor has not been tested unlike OAPRW which has been tested in pilot plant scale.

Ecological impacts of natural estrogens and xenoestrogens in treated wastewater include altered sexual development and sex ratios among continuously exposed organisms. The primary sources of estrogenic activity in wastewater are natural estrogens such as estrone, 17β-estradiol and estriol and synthetic compounds like 17α- ethinylestradiol, alkylphenols and alklphenol ethoxylates. Precursors in raw wastewater can yield estrogenic intermediates during wastewater treatment. All these compounds can be destroyed by biochemical processes conventional wastewater treatment processes, suggesting that conventional processes can be optimized for removal of estrogenic activity from wastewater. Sorption to sludges derived from wastewater treatment affects the fates of hydrophobic xenoestrogens such as nonylphenol, in part because the biodegradability of sorbed contaminants is limited. It may also be possible to tailor sludge stabilization processes to remove trace contaminants, including estrogens. For example, there are significant differences in the efficiencies of aerobic and anaerobic digestion for destruction of alkylphenols and probably other estrogenic compounds with aromatic moieties. Because advanced wastewater treatment is not economically feasible for most communities, there is ample incentive to develop accurate relationships between operational parameters and removal of estrogenic compounds during secondary wastewater treatment. Large quantities of polybrominated diphenyl ethers (PBDEs) have been used as flame retardants in clothing and plastic products since the 1970s. A small fraction of the PBDEs in manufactured products subsequently enters municipal wastewater. The resistance of these compounds to chemical and biochemical transformations provides opportunities for accumulation in sediments. Balances developed for PBDE congeners indicate that conventional wastewater treatment processes and soil infiltration of treated wastewater in recharge operations do not discriminate significantly among the major congeners in commercially available PBDE products. Accumulation of PBDEs at near part-per-million levels was measured in the sediments at the Sweetwater Recharge Facility in Tucson, Arizona, during 10-15 years of operation. Half times for loss of major PBDE congeners from sediments were decades or longer. Local agricultural soils amended with biosolids over a 20-year period showed similar accumulation of PBDEs. The widespread use of PBDEs in commercial products, compound persistence and toxicity indicate that additional effort is warranted to better understand fate-determining processes for PBDEs in the environment.

In this literature review the characteristics of two free-floating macrophytes, water hyacinth   (Eichhornia crassipes) and duckweed (Lemna sp.), and two microalgae, Chlorella and Scenedesmus, have been examined regarding their suitability as efficient nutrient removers in the treatment of wastewater with high levels of nutrients and suspended solids from a biogas plant in Loudden. The needs required for the plants to be able to grow in wastewater and the amounts of biomass they can produce have also been studied. The results show that Chlorella is capable of a very high uptake of nutrients in photobioreactors with high nutrient loadings. With an ammonia uptake maximum value at 10900mg/m2/d Chlorella outshines the other organisms in this study. The test organism that performed the closest to Chlorella in terms of nitrogen uptake was water hyacinth with an uptake about 1602mg/m2/d. One factor affecting nutrient uptake in a positive way is the growth rate. Free-floating macrophytes produce more biomass than algae do, and water hyacinth have been shown to be the most productive. It is important to conduct a regular harvest of the plants if a high production should be maintained. High quantity of biomass per unit area can inhibit the growth, and algae are more sensitive to this than the macrophytes often suffering from self-shading when the density is too high. The high level of nutrients in the wastewater prevents growth and dilution is required to achieve any growth at all. Therefore, conventional treatment methods might prove to be a better option.

Textile dyes are molecules designed to impart a permanent colour to textile fabrics. They pose an environmental problem because they are toxic and they decrease the aesthetic value of rivers and lakes. Current technologies for dye removal cannot remove all classes of dyes and two or more technologies are usually combined to achieve statisfactory decolourization efficiencies. Lignin-degrading enzymes like laccases are potential technologies for dye decolourization and decolourization with immobilized laccase has been intensively investigated. The majority of those studies however have focused on dye disappearance and several reported that significant dye adsorption had occured during the dye removal, making the role of the enzyme unclear. Moreover, textile wastewaters contain auxiliary chemicals that can impact enzymatic dye decolourization and very few studies have evaluated the impact of those substances on laccase. This research evaluated the feasibility of treating dye-contaminated textile wastewaters with an immobilized laccase system. The first sub-objective was to examined the decolourization of Reactive blue 19 (an anthraquinone dye) by Trametes versicolor laccase immobilized on controlled porosity carrier (CPC) silica beads and the second was to analyze the kinetic effects of a non-ionic surfactant Merpol, sodium sulfate, and sodium chloride on laccase decolourization of Reactive blue 19. Decolourization of Reactive blue 19 by immobilized laccase was mainly enzymatic although dye some adsorption occurred. Decolourization led to less toxic by-products from azo and indigoid dyes whereas increased toxicity was observed for anthraquinone dyes. The feasibility of immobilizing laccase on poly(methyl methacrylate) (PMMA) through its sugar residues with a simple procedure was demonstrated and the mass of enzyme immobilized compared well with other commercial acrylic supports. The decolorization of Reactive blue 19 by laccase was inhibited by the non-ionic surfactant, Merpol by substrate depletion. A model describing this inhibition was developed and was validated by a saturated equilibrium binding experiment. While sodium sulfate (ionic strength) had no effect on either ABTS oxidation or dye decolourization, sodium chloride inhibited laccase during dye decolourization and the type and nature of the inhibition depended on the substrate. With ABTS, the inhibition was hyperbolic non-competitive whereas it was parabolic mixed with Reactive blue 19. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2009-06-16 16:58:47.753

Pharmaceutically active compounds (PhACs) have been found in wastewater effluents and receiving waters around the world. As yet there are no jurisdictions that regulate their release, or their impact on receiving water ecosystem health. The issue is complex due to the number of PhACs that exist, the variability in their structure and function, the variability in removal during different wastewater treatment processes, the potential for formation of metabolites and transformation products, and a lack of information on the impacts due to their presence on receiving waters. Gemfibrozil is a lipid regulating drug that is commonly found in wastewater effluents and receiving waters. It has been shown to partially degrade during biological wastewater treatment processes and has also been shown to produce reaction products through reactions with free chlorine. This thesis investigated the removal and transformation of gemfibrozil through several different wastewater treatment processes, namely biological removal and chlorination. Reactions between gemfibrozil and free chlorine led to the identification of four reaction products. The structures of three of the four reaction products were elucidated. The kinetics of formation of these reaction products were then investigated at a range of pH values, and in two wastewater matrices. One reaction product, 4’-ClGem was shown to form under conditions relevant to wastewater treatment. The impacts of gemfibrozil and 4’-ClGem presence on the abundance of suspended and biofilm bacteria in a simulated receiving water experiment were evaluated. It was shown that changes in the water matrix had more of an impact on bacterial abundance than presence of gemfibrozil or 4’-ClGem. A bacterial dose-response experiment showed a negative response at 10 mg/L exposure to 4’-ClGem, which is orders of magnitude higher then what would be found in receiving waters. In order to prevent the formation of chlorinated reaction products, it is necessary to remove gemfibrozil prior to disinfection. Recirculating biofilters (RBS), a biological technology for onsite or small-scale wastewater treatment, were explored as a potential treatment process for gemfibrozil removal. Results indicate that RBFs show promise as a robust technology to remove greater than 50% of influent gemfibrozil.

Endocrine disrupting compounds (EDCs) in the environment have recently emerged as a major issue in Canada and around the globe. The primary objective of this thesis was to investigate the fate of EDCs in two wastewater treatment processes, membrane bioreactors (MBRs) and ultraviolet (UV) disinfection. Two submerged MBR systems using hollow fiber membranes from two membrane manufacturers were tested. The results from a bench-scale and a pilot scale MBR for the treatment of swine wastewater with high concentration of EDCs showed that over 94% of the estrogenic activity (EA) in the influent was reduced through the MBR process. Biological degradation was the dominant removal mechanism for the removal of EDCs in MBRs. Over 85% of the influent EA was reduced by biodegradation through the MBR process. The other MBR system was built to study the removal mechanisms of two estrogens in a hybrid MBR with the addition of powdered activated carbon (PAC). The effects of PAC dosing on MBR overall performance was studied as well. It was found that PAC dosing could increase the removal rates of 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) by 3.4% and 15.8%, respectively and result in a slower rate of trans-membrane pressure (TMP) increase during MBR operation, which could significantly reduce the operating cost for membrane cleaning and/or replacement. The operating cost for PAC dosing could be offset by the benefit achieved from reducing the cost for membrane maintenance. The slower rate of TMP increase in the PAC-MBR was associated with the lower concentrations of soluble extracellular polymeric substances and colloidal organic compounds in the PAC-MBR sludge. The degradation kinetics of three estrogens, estrone (E1), E2, and EE2 in de-ionized water by UV irradiation was studied. The experimental results showed both the apparent concentrations and overall EA of all three investigated estrogens in water decreased with direct UV irradiation. To further study the impact of UV on the overall EA of wastewater, the EA of pre-UV and post-UV samples from five wastewater treatment plants were measured in both liquid and solid phase by Yeast Estrogen Screen assay. It was found that the EA of wastewater decreased after UV disinfection in three of the investigated plants whereas it increased in the other two plants. This observation needs to be further studied because it might have significant impacts on the application of UV systems for wastewater disinfection.