Currently in Taiwan¡¦s textile-dying industry, sodium hypochlorite (NaOCl) is popularly used as a decolorization oxidant. In order to surely meet the effluent color regulation of 550 ADMI (American Dye Manufactures Institute), excessive dosage of sodium hyperchlorite is commonly used, which results in the increase of residual chloride and the accumulation of toxic chlorinated compound in the environment. This study probes into the characteristics of substitute oxidant for sodium hypochlorite to avoid the production of toxic products. The study includes decolorization efficiency evaluation, economical analysis and feasibility of commercial application. This study adopts ozone as an oxidant and ultraviolet light as the oxidant enhancer for the purpose of preventing the occurrence of secondary pollution products like trihalomethane from the sodium hyperchlorite application. Literature review indicates that there are several studies for reaction mechanisms of oxidation and disinfection of ozone and ultraviolet light for decolorization and the conclusions reveal much promising results. There are three topics in this study, which are: Topic 1: Feasibility study. This study focuses on whether the effluent color concentration of the treatment process meets the color effluent standard or not. A 3.5 L volume reactor was used in this section. Topic 2: Influencing factor analysis. A 14 L volume reactor was adopted for analyzing the influencing factors for decolorization and for comparing the differences in treatment efficiencies between a dye finishing plant effluent and two commercial dyestuff samples. Topic 3: Economic analysis. The analysis focuses on economic comparison between NaOCl and UV/Ozone processes for effluent decolorization. Analysis results of the investment cost, operation/maintenance expense, and investment return duration are presented in this section. A 50 L volume reactor was used to achieve the evaluation for this part. First topic of this study examined some operating parameters for treating effluent from the biological and chemical coagulation units of a dye-finishing wastewater treatment plant using the UV/Ozone technique to meet an effluent regulation of 550 ADMI values could be reduced from approximately 4,000 to 200 ADMI in an hour using the UV/Ozone technique. The results show that higher color removal efficiency could be achieved at pH values around 3 as compared with higher pH values of around 7 and 10. This might be due to the fact that the predominant ozone molecules at lower pH values are more selective to certain chromophore molecules in wastewater, despite the fact that hydroxyl radicals are predominant at higher pH values and have a stronger oxidation capability than ozone. The UV light used in this study emitted from the experimental lamp can excite oxygen and water molecules to produce ozone molecules and hydroxyl radicals that can then increase decolorization rate. The findings of this investigation reveal that the proposed UV/Ozone treatment scheme has potential for development into an environmentally friendly decolorization approach for dye finishing wastewater treatment. The second topic is to investigate the feasibility of applying UV/Ozone techniques to reduce color content caused by two commercial reactive dyes (Orange-13 and Blue-19). Bench experiments were performed using a 14-L reactor. Controlling factors including pH value, dosage of ozone, reaction time, and UV intensity were evaluated to obtain the optimal operating parameters. Results from this study show that the ozone dosage and pH value dominated the effects on the decolorization process. However, UV intensity shows relatively insignificant effects. Results also indicate that the color content could be reduced from 2,000 to 200 ADMI within a reaction time of 30 minutes with a total ozone dosage of 100 mg/L. This study shows that pH values of approximately 3 and 10 favored the decolorization of the studied Dye Blue-19 and Orange-13, respectively. This was due to the effects that molecular ozone and hydroxyl radicals had significant oxidative power at low and high pH, respectively. Moreover, molecular ozone was more selective to certain dye structures during its oxidation process. This also caused the effect that pH value played an important role on color removal. Kinetic analyses show that the decolorization reactions of Dye Orange-13 and Blue-19 followed a first-order decolorization model. Experimental results also indicate that the degree of decolorization was primarily proportional to the ozone dosage. Results from this study provide us an insight into the characteristics and mechanisms of decolorization by UV/ozone technique. Results will also aid in designing a system for field application of dye finishing plants. According to the results from the third topic, for a dye finishing plant of wastewater flow rate of 800CMD (m3/day), the capital cost of equipment and related establishment as well as amendment is about US$ 116,300, and the monthly operation and maintenance cost is US$ 4,030. In this study, ozone was used as a substitute decolorizing oxidant to treat the effluent from the secondary biological and physical/chemical treatment plant. Because the current cost for the decolorization oxidant (NaOCl) is approximately US$ 5,700 per month, the monthly saving, adopting the decolorization system using UZ/Ozone, will be US$ 1,670. The investment return period will be over 7 years and is not attractive to the plant owners. However, to prevent the accumulated toxicity of chloride compounds in the environment and to promote the desires of investment on the advanced decolorization technique, a favorable tax deduction policy needs to be applied.

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.

In most cases, data from petroleum industry wetland studies indicate that treatment wetlands are equally or more effective at removing pollutants from petroleum industry wastewaters than from other types of wastewater. In this study, we discussed the treatment efficiencies of oil-refinery industry wastewater by pilot-scale constructed wetland systems .The constructed wetland systems were one free water surface system filled with the sandy media and one subsurface flow system filled with the gravel media operated in parallel. Each system planted with Phragmites communis. The hydraulic retention time for the treatment wetland was controlled in turn at 0.96, 0.48, and 0.72 days. The experimental results showed that all of these contaminants could be reliably removed from wastewater by treatment wetland, especially the FWS. The effluents from the constructed wetland systems reusing and recovering were feasible.

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.

In this study, two types of chemical mechanical polishing wastewaters (designated Cu-CMP wastewater and mixed-CMP wastewater, respectively) from a wafer fabrication plant was treated by a simultaneous electrocoagulation/electrofiltration (EC/EF) process using laboratory-prepared TiO2/Al2O3 composite membranes. First, tubular membrane supports of Al2O3 were prepared by the extrusion method. Then the slip composed of nanoscale TiO2 (prepared by sol-gel process) and 1 wt% of corn starch was applied on the aforementioned tubular membrane supports by the dip-coating method, followed by sintering to obtain tubular TiO2/Al2O3 composite membranes. These tubular inorganic composite membranes then were incorporated into an EC/EF treatment module for the treatment of CMP wastewaters. The permeate qualities were evaluated. In addition, the effects of different operating modes (i.e., the flow-through mode and recirculation mode) on membrane flux and permeate quality were conducted. Finally, the effects of changing the backwash time and backwash cycle on the membrane flux were also investigated. Experimental results have shown that the slip containing 75 v/v% of TiO2 sol and 25 v/v% of corn starch solution would yield a membrane layer with a thickness of 13 £gm and a pore size of 15 nm. On the CMP wastewater treatment, the removal efficiencies of copper ion and total organic carbon (TOC) were found to increase with the increasing electric field strength. This relationship, however, did not apply to other water quality items. Under the optimal operating conditions of using the recirculation mode, the removal efficiencies for turbidity and TOC for Cu-CMP wastewater were determined to be 98% and 90%, respectively. Similarly, a turbidity of < 1 NTU (a removal efficiency of 99%) was obtained for mixed-CMP wastewater. By using the same optimal operating conditions for the recirculation mode to treat Cu-CMP wastewater, initial fluxes of 300 L/h¡Em2 and 280 L/h¡Em2 were obtained for the flow-through mode and recirculation mode, respectively. The corresponding initial fluxes for mixed-CMP wastewater were 370 L/h¡Em2 and 360 L/h¡Em2, respectively. For the case of the recirculation mode, the removal efficiencies of total solids content, silicon, copper ion, TOC, and turbidity for Cu-CMP wastewater were 71%, 85%, 72%, 90% and 99%, respectively. The corresponding removal efficiencies of 68%, 88%, 78%, 90% and 99%, respectively were determined for the case of the flow-through mode. On the other hand, the removal efficiencies of total solids content, silicon, TOC, and turbidity for mixed-CMP wastewater using the recirculation mode were 76%, 84%, 78% and 99%, respectively; whereas 78%, 86%, 72% and 99%, respectively for the flow-through mode. Based on the above findings, the operating mode is not a significant parameter in influencing the membrane flux and quality. Permeate obtained in this work was found to be recyclable for the use in irrigation and make-up water for cooling towers. Backwashing was found to be important to the membrane flux in this study.

The electroplating wastewater is usually treated by chemical precipitation, and the generated sludge has loose structure to cause the difficulties in sedimentation and filtration. Moreover, the sludge is unstable and the contained heavy metals are easily leached. Solidification is one method to deal with this kind of sludge; however it cause another problem, land requirement. In this study, the contents of electroplating wastewater are divided into two parts organic matters and heavy metals; organic matters are treated by Fenton method and heavy metals are by Ferrite process. The purpose of this study is that through the serial Fenton-Ferrite Process treatment the effluent water and the sludge generated from the procedure could meet the standards in Taiwan. It was well-know that the primary operation factors of Ferrite Process are pH, reaction temperature, ferrous ion concentration, time and aeration. The results showed that the proper factors of FP were pH=10, temperature= 90¢J, Fe/M molar ratio= 7,reaction time=80 min and aeration rate=1.0 L air / min / L solution. However, in Fenton method, the parameters of pH, hydrogen peroxide, ferrous ion concentration, and reaction time were discussed. I had greatest efficiency under the data showed that Fenton method pH = 3, ferrous ion concentration=3000 mg/L, hydrogen peroxide = 13000 mg/L, and reaction time=2 hr. The wastewater measured COD =1162 mg/L, Cr=70 mg/L, Zn=400 mg/L. The treatment efficiency of the procedure combining Fenton method and Ferrite Process were that COD=88.5 mg/L, Cr=1.06 mg/L, and Zn=0.98 mg/Lin effluent water and the TCLP test results of sludge were Cr=3.37 mg/L, Zn=2.46 mg/L. All the data showed that the combination of the two process can significantly treat wastewater to meet the standards. Furthermore, the sludge can be recycled as magnetic materials or other purposes due to it¡¦s specific properties.

Water is essential for life as well as industrial growth. Therefore, this research is mainly to explore the treatment capacity of LCD (Liguid Crystal Display) industrial wastewater recycling by a simultaneous electrocoagulation/electrofiltration (EC/EF) process using laboratory-prepared multi-tubular TiO2/Al2O3 composite membranes. First, tubular membrane supports of Al2O3 were prepared by the extrusion method. Then the slip composed of nanoscale TiO2 (prepared by sol-gel process) was applied on the aforementioned tubular membrane supports by the dip-coating method, followed by sintering to obtain tubular TiO2/Al2O3 composite membranes. Then, two types of LCD industrial wastewaters (designated TFT-LCD wastewater and STN-LCD wastewater, respectively) from different LCD fabrication plants were treated by EC/EF process using TiO2/Al2O3 composite membranes. Moreover, the permeate qualities were evaluated under the recirculation-mode operation. In addition, the effects of different operating parameters (i.e., electric field strength, trans-membrane pressure, and crossflow velocity) on membrane flux and permeate quality were evaluated. Relations of the water quality and the different operation modes (i.e., the recirculation mode, flow-through mode, and secondary treatment mode) were also discussed. Finally, the effects of changing the backwash time and backwash cycle on membrane flux were investigated. In the recirculation mode, both kinds of wastewater achieved a satisfactory organics and anion removal. An average of about 90¢H of COD (Chemical Oxygen Demand) and TKN (Total Kjeldahl Nitrogen) could be removed. For anions (i.e., NO3¡Ð, NO2¡Ð, Cl¡Ð and SO42¡Ð), their removal efficiencies were all over 90%. Furthermore, TOC (Total Organic Carbon) and turbidity also had removal efficiencies of over 98%. When the operation mode was changed from the recirculation mode to flow-through mode, the changes of permeate quality were not obvious. But the cumulative quantity of permeate of the flow-through mode was greater than that of the recirculation mode. As for the experimental result of the secondary treatment mode, the permeate qualities were found to be improved. In this case, an average removal of over 95% of NO3¡Ð, NO2¡Ð, Cl¡Ð, and SO42¡Ð could be obtained. According to experimental results shown above, the treated water could be recycled and reused as the cooling tower make-up water if its pH and conductivity values were reduced. However, these problems could be easily resolved by proper adjustments of pH. Overall speaking, the tubular TiO2/Al2O3 composite membranes and simultaneous EC/EF treatment module employed in this work are capable of treating LCD industrial wastewater for the purpose of reclamation.

The crisis of the water resources become a serious problem in recent years. Besides the global warming the problem mostly comes from quick population growth, intense industrial developments and low efficiency agricultural implementations. Biofilters are widely been used to either reduce pollution loads or also as a water conservation tool. And the vertical-flow biofilters act as a kind of bio-filter has gain the advantages of low maintenance, small footprint, greater capacities on both the hydraulic and organic loadings. It often used in to treat aquaculture wastewater for recycling during the filter stage. This study is, therefore, focusing on the bio-treatment processes to recycle the wastewater discharged from Chlorella production. Preserving water resources is one big issue of this study, Reuse the nutrients is another tough objective. For reusing the water with as much nutrients as possible and get the organic content off the water is the major target of the study. This study has been separated in two stages. A preliminary study has first been carried out in order to understand the Chlorella behaviors in more detail. Second phase includes the treatment tests with conventional activated sludge (AS) method and the bio-filters. The results have shown that ammonia is preferred by Chlorella as the nitrogen source. Light plays an important role on the treatment for removing algae activities. Aerobic digestion has shown better efficiency. AS can accept as high as 20% of daily input to the system volume, the system is not capable to bear more. While the biofilters, using either zeolite and LECA as the media, have shown satisfied results. When the hydraulic loading stay between 0.30 ~ 2.09 m3 m-2 day-1 to the system, the SS, COD, Chl-a removal rates can reach 90%, and more than 96% of total inorganic nitrogen (TIN) and 76% phosphorus can be preserved in the recycled water, respectively.

<p>Decolorization of Azo dyes in synthetic wastewater composition which is similar to real textile wastewater was carried out by microbial process. Experiments were performed in two continuous systems. Experiments were performed under anaerobic conditions in order to break the nitrogen bond of the azo group (-N=N-). A synthetic dye solution which contained 200 mg/L Reactive Black 5, 200 mg/L Procion Red MX-5B and 1 g/L yeast extract was prepared. In this study, living microorganisms were used to degrade the dyes in wastewater. Rice husks which contain bacteria and fungi were used in the reactors of continuous systems. The parameters tested on continuous system were wastewater composition, the number of reactors, the amount of yeast extract in wastewater composition, the wastewater flowrate, washing the system with wood chips solution, addition of yeast extract solution.  Results have shown that increasing the number of reactors, the retention time, the amount of yeast extract and washing the system with wood chips solution had positive effects for degradation of the dyes from wastewater. When the flowrate was increased the retention time has decreased so degradation of dyes has decreased but although the flowrate increased twice, % degradation hasn’t decreased as the same ratio. Therefore this result showed that this process can be worked for faster flowrates. Microbial process is a promising technology which might be used to treat wastewater containing azo dyes with good performance.</p><p> </p>