我國自2000年土污法公布施行以來，至今(2012年)已逾12年，但綜觀環保署之國內場址列管情形統計資料可知，目前我國正面臨污染土地整治推動遲緩的問題。整理國內外相關文獻可知污染土地整治有其必要性，其原因在於如果污染土地持續閒置且不整治重新利用，不僅導致污染土地所造成的問題無法解決，另一方面也會使污染土地因整治而帶來的效益無從實現。而污染土地整治遲緩可能來自污染土地市場存在外部性難以內部化的情形，因此如何解決市場失靈之現象為其關鍵所在。 國外解決污染土地市場失靈的作法，主要分為「誘因給予」與「處罰」二大方式。本研究進一步將其概念透過問卷調查與實際訪談之方式，探討我國污染土地地主及承租人於整治污染土地實務上所面臨的困難，及對促進污染土地再利用相關作法之看法。 實證結果顯示，整治污染土地所面臨的最主要困難為整治經費過高、環境顧問公司市場混亂。於促進污染土地整治再利用的作法上，絕大多數地主及承租人偏好誘因給予方式，例如補助整治經費與減免相關稅負；相對地，較不贊成處罰方式，其原因在於增加財務負擔可能提高污染行為人放棄整治的風險，進而阻礙污染土地的整治再利用。此外，公開污染土地相關資訊供污染行為人參考、引進環境保險相關制度等作法，對未來污染土地整治之推行亦有極大助益。 從實證結果進一步歸納可知影響污染土地整治的因素包含「個別因素」與「總體因素」，並將其發展出一套污染土地分類模式。實際應用我國污染土地統計資料於該模式可知，放棄整治此類型的土地占我國污染土地總面積相當低之比例。因此，政府如能有效推動全面性基礎制度的建置，並搭配相關作法，我國在污染土地的整治推行上應能達到不錯之成效。 / It has been over 12 years since the announcement of Soil and Groundwater Act in year 2000 in Taiwan. However, statistics revealed by the Environmental Protection Administration suggests that the progress of remediation of contaminated land is far from satisfactory. A number of studies have pointed out that if contaminated land continues to be idle, not only can contamination not be solved, but also benefits resulting from remediation are lost. The market for contaminated land suffers from the external effects that in turn lead to a slow pace of remediation. Therefore, how to solve the problem of market failure is the key to promotion of reusing contaminated land. There are two major approaches to alleviating the problems of market failure for contaminated land; they are incentives and liabilities, respectively. In this study, we investigate into landowners and tenants of contaminated land through questionnaires and face-to-face interviews. We intend to discover the difficulties they have encountered in practice and also their views in respect of the approaches that might stimulate the reuse of contaminated land. Empirical results show that the primary difficulties on remediation are the excessive costs and dissatisfactory service of environmental consulting firms. Besides, among the alternative approaches that are expected to accelerate remediation, interviewees tend to prefer incentives over liabilities. They argue that if the government imposes liabilities upon landowners and tenants, their possibility of giving up remediation will be raised. Furthermore, supply of more complete information and introduction of environmental insurance are thought to be able to facilitate remediation in the future. Overall, the empirical evidence highlights a number of contributing factors to an effective remediation. To take a step further, we develop a model to classify the contaminated land in terms of their characteristics such as location, land values…etc. Application of this classification model to two cities suggests that contaminated land that needs direct governmental subsidy only accounts for a small proportion of the total contaminated areas. As a result, we urge the government to establish a platform to provide comprehensive and transparent information. This information platform shall be able to significantly improve the progress of remediation of contaminated land largely through the reinstatement of market mechanism.

Contaminated aquatic sediments pose health risks to fish, wildlife, and humans and can limit recreational and economic uses of surface waters. Technical and cost effective in situ approaches for sediment management and remediation have been identified as a research need. Subaqueous in situ capping is a promising remedial approach; however, little is known regarding its impact on underlying sedimentary processes and the feasibility of bioaugmented caps at sites subject to contaminated groundwater seepage. This work specifically addresses (1) the impact of capping on biogeochemical processes at the sediment-water interface, (2) the ability and degree to which indigenous sediment microorganisms colonize an overlying cap, (3) the effect of advective flow direction on redox conditions within a cap, (4) natural contaminant bioattenuation processes within capped sediment, and (5) limitations toward a functional bioreactive in situ cap. Laboratory-scale experiments with capped sediment columns demonstrated that emplacement of a sand-based in situ cap induced an upward, vertical shift of terminal electron accepting processes into the overlying cap while simultaneously conserving redox stratification. Upflow conditions simulating a groundwater seep compressed anaerobic processes towards the cap-water interface. Microorganisms indigenous to the underlying sediment colonized cap material and spatial population differences generally reflected redox stratification. Downflow of oxic surface water through the cap, simulating tidally-induced recharge, created fully oxic conditions within the cap, demonstrating that flow direction strongly contributes to redox conditions. Experiments simulating capped sediment subject to contaminated groundwater seepage revealed a reduction of natural bioattenuation processes with time, stemming from the elimination of labile organic matter deposition to the sediment and a subsequent lack of electron donor. Thus, parent contaminants within groundwater seeps will be subject to minimal biotransformations within the sediment before entering a reducing cap. A bioreactive cap, inoculated with microorganisms capable of reductive dehalogenation, was established to reductively dechlorinate tetrachloroethene present in the groundwater; however electron donor amendments to sediment effluent were required to achieve complete dechlorination of tetrachloroethene to non-toxic ethene. Results from this work improve understanding of biogeochemical and bioattenuation processes within capped aquatic sediments and should aid in the development of active capping technologies.

Uranium contamination of soils and groundwater at Department of Energy facilities across the United States is a primary environmental concern and the development of effective remediation strategies is a major challenge. Bioremediation, or the use of microbial enzymatic activity to facilitate the remediation of a contaminant, offers a promising in situ approach that may be less invasive than traditional methods, such as pump and treat or excavation. This study demonstrates for the first time the successful biomineralization of uranium phosphate minerals as a result of microbial phosphatase activity at low pH in both aerobic and anaerobic conditions using pure cultures and soils from a contaminated waste site. Pure cultures of microorganisms isolated from soils of a low pH, high uranium- and nitrate-contaminated waste site, expressed constitutive phosphatase activity in response to an organophosphate addition in aerobic and anaerobic incubations. Sufficient phosphate was hydrolyzed to precipitate 73 to 95% total uranium as chernikovite identified by synchrotron X-ray absorption spectroscopy and X-ray diffraction. Highest rates of uranium precipitation and phosphatase activity were observed between pH 5.0 and 7.0. Indigenous microorganisms were also stimulated by organophosphate amendment in soils from a contaminated waste site using flow-through reactors. High phosphate concentrations (0.5 to 3 mmol L-1) in pore water effluents were observed within days of organophosphate addition. Highest rates of phosphatase activity occurred at pH 5.5 in naturally low pH soils in the presence of high uranium and nitrate concentrations. The precipitation of uranium phosphate was identified by a combination of pore water measurements, solid phase extractions, synchrotron-based X-ray spectroscopy, and a reactive transport model. The results of this study demonstrate that uranium is biomineralized to a highly insoluble uranyl phosphate mineral as a result of enzymatic hydrolysis of an organophosphate compound over a wide range of pH, in both aerobic and anaerobic conditions, and in the presence of high uranium and nitrate concentrations. The nonreductive biomineralization of U(VI) provides a promising new approach for in situ uranium bioremediation in low pH, high nitrate, and aerobic conditions that could be complementary to U(VI) bioreduction in high pH, low nitrate, and reducing environments.

No description available.

The ever-increasing detection of harmful organic and inorganic compounds in habitable areas throughout the world has led to mounting research into applications and techniques for the treatment of contaminated soils, surface and groundwaters, and chemical and industrial wastewaters. Chemical oxidation technologies, in particular Fenton-based remediation systems, have exhibited considerable potential for the effective treatment and remediation of such contaminated waters and soils. The use of Fenton-based oxidation systems for the treatment of contaminated waters and wastewaters warrants the development of kinetic models capable of accurately simulating system behaviour. In this thesis, the kinetics of Fenton-mediated oxidation systems and kinetic models based on its governing reaction mechanism are investigated in order to highlight those parameters and conditions that effect Fenton chemistry and oxidation performance, and to demonstrate the application of such kinetic models to design and improve treatment systems. Experimental and simulated data describing the oxidation of formic acid by Fenton's reagent at low pH (3 to 4) and under a variety of initial conditions, operating regimes, and solution environments supports a proposed reaction mechanism that nominates the hydroxyl radical (OH) as the active oxidizing intermediate in Fenton-based oxidation systems. Laboratory experiments demonstrate that formic acid oxidation is inhibited in the presence of oxygen, and model simulations of these systems reveals that such behaviour is due to the effect organic radical intermediates and/or by-products have in assisting or hindering the redox cycling of the catalytic iron species. The critical role that iron redox cycling plays in affecting oxidation performance is further highlighted by experimental and simulated studies at alternate pHs and using different target organics, including those that react directly with iron in a redox capacity. Experiments at pH 4 reveal an increase in the redox cycling of iron and improved oxidation performance compared to pH 3 as the higher pH favours the superoxide radical, a stronger reductant than the hydroperoxyl radical that predominates at pH 3. Other laboratory and modelling studies on the Fenton-mediated oxidation of certain aromatic compounds highlight the manner in which quinone and quinone-like compounds, being added directly or generated as oxidation by-products, can improve oxidation performance via redox reactions with iron. Further simulations reveal the type of practical design and operating information kinetic models can provide for treatment processes, though it is noted an appropriate understanding of the oxidation mechanism of the target species is necessary for the accurate application of the model.

A phosphorus rich wastewater, typical of a dairy processing site producing milk powder, was biologically treated in a continuous activated sludge reactor. A literature review indicated there was a vast amount of information on the mechanisms of the Enhanced Biological Phosphorus Removal (EBPR) process and its application to domestic wastewaters, but little successful research on its application to dairy processing wastewater. The biodegradability of the wastewater organic fractions was assessed due to their impact on the EBPR process. Continuous anaerobic fermentation tests were used to determine the concentration of volatile fatty acids that could be generated, as these are required for successful EBPR. A fermenter hydraulic retention time of 12 hours and a temperature of 35 °C generated the highest concentration of volatile fatty acids, with an acidification rate of 65% (based on 0.45µm filtered COD). To permit improved dissolved oxygen control and increased flexibility, a multi-zone reactor was designed. A fermentation stage was also incorporated prior to the activated sludge reactor. This reactor was operated with anaerobic, anoxic and aerobic zones at an SRT of 10 days and stable biological phosphorus removal was achieved. A maximum of 41.5 mg P/L was removed and phosphorus release and PHA storage occurred in both the anaerobic and anoxic zones. The soluble COD consumed in the unaerated zones (anaerobic + anoxic) totalled 484 mg COD/L on the day of the zone study (day 158). The aerobic sludge phosphorus concentration averaged 7.0% mg P/mg VSS after system optimisation. The anaerobic volume was doubled in order to increase the anaerobic consumption of volatile fatty acids. This change increased the amount of soluble COD consumption in the unaerated zones to 632 mg P/L after 40 days but did not result in a significant increase in biological phosphorus removal. In the next series of trials, the concentration of nitrogen in the wastewater was decreased and the anoxic zone removed. This change did not improve the amount of biological phosphorus removal, which was 35 mg P/L at an SRT of 10 days. The effect of different sludge retention times was then investigated. Increasing the SRT to 15 days resulted in little change in phosphorus removal (34.5 mg P/L). Decreasing the SRT to 5 days resulted in the loss of EBPR. The medium term effect on the EBPR process by removing the fermentation stage was also assessed using an AO configuration at an SRT of 10 days. The amount of phosphorus removed decreased slightly after 34 days to 34 mg P/L, but the soluble COD consumed in the anaerobic zone increased to 624 mg P/L. It was concluded that a stable EBPR process could be established when treating a dairy processing wastewater with a continuous activated sludge reactor. The biological stability was sensitive to changes in the solids retention time and the removal of the fermentation stage.

The aim of this research was to investigate the feasibility of co-digestion of municipal primary sludge and whey by anaerobic CSTR (Continuous Stirred Tank Reactor), as well as the factors that affect the performance of the co-digestion reactors. Before studying the co-digestion process, a semi-continuous whey digestion experiment was conducted to analyze the feasibility of anaerobic digestion of whey along with pH control. The results obtained from the study indicated that supplement of nutrients, trace elements as well as heavy metals was necessary to maintain the anaerobic whey digestion system. To investigate the co-digestion of primary sludge and whey process, the effects of pH, OLR (Organic Loading Rate), HRT (Hydraulic retention time) as well as the COD (Chemical Oxygen Demand) loading ratio of primary sludge to whey on the performance of the reactors were studied. The results of the co-digestion experiments demonstrated that it was feasible to co-digest primary sludge and whey without nutrient, trace element and heavy metal supplement. The TCOD (Total Chemical Oxygen Demand) removal efficiency and the biogas production of the co-digestion system increased with the increase of OLR. At same OLR, digestion of the mixture of primary sludge and whey with higher whey content achieved higher biogas production and TCOD removal efficiency. The anaerobic co-digestion of primary sludge and whey process performed successfully at OLR of 5.8 ± 0.1g COD/l.d without pH control when the COD loading ratio of primary sludge to whey was approximately 70:30, due to the fact that the primary sludge may serve as buffering reagent. By adding sodium bicarbonate (NaHCO3) to maintain the pH at 6.9 ± 0.1, the OLR of the co-digestion reactor could reach 8.1 ± 0.1 g COD/l.d at HRT of 20 days. Moreover, by co-digestion of primary sludge and whey solution, the reactor could be operated successfully at HRT of 10 days and at OLR of 7.6 ± 0.1 g COD/l.d with COD loading ratio of primary sludge to whey of 53 : 47. The biogas production (3.2 ± 0.1 l/d) was 1.5 l/d higher than digestion of the same amount of primary sludge alone (1.7 ± 0.1 l/d).

The aim of this research was to investigate the feasibility of co-digestion of municipal primary sludge and whey by anaerobic CSTR (Continuous Stirred Tank Reactor), as well as the factors that affect the performance of the co-digestion reactors. Before studying the co-digestion process, a semi-continuous whey digestion experiment was conducted to analyze the feasibility of anaerobic digestion of whey along with pH control. The results obtained from the study indicated that supplement of nutrients, trace elements as well as heavy metals was necessary to maintain the anaerobic whey digestion system. To investigate the co-digestion of primary sludge and whey process, the effects of pH, OLR (Organic Loading Rate), HRT (Hydraulic retention time) as well as the COD (Chemical Oxygen Demand) loading ratio of primary sludge to whey on the performance of the reactors were studied. The results of the co-digestion experiments demonstrated that it was feasible to co-digest primary sludge and whey without nutrient, trace element and heavy metal supplement. The TCOD (Total Chemical Oxygen Demand) removal efficiency and the biogas production of the co-digestion system increased with the increase of OLR. At same OLR, digestion of the mixture of primary sludge and whey with higher whey content achieved higher biogas production and TCOD removal efficiency. The anaerobic co-digestion of primary sludge and whey process performed successfully at OLR of 5.8 ± 0.1g COD/l.d without pH control when the COD loading ratio of primary sludge to whey was approximately 70:30, due to the fact that the primary sludge may serve as buffering reagent. By adding sodium bicarbonate (NaHCO3) to maintain the pH at 6.9 ± 0.1, the OLR of the co-digestion reactor could reach 8.1 ± 0.1 g COD/l.d at HRT of 20 days. Moreover, by co-digestion of primary sludge and whey solution, the reactor could be operated successfully at HRT of 10 days and at OLR of 7.6 ± 0.1 g COD/l.d with COD loading ratio of primary sludge to whey of 53 : 47. The biogas production (3.2 ± 0.1 l/d) was 1.5 l/d higher than digestion of the same amount of primary sludge alone (1.7 ± 0.1 l/d).

Anaerobic ponds are an established technology for treating farm dairy effluent in New Zealand. These ponds produce a significant amount of methane but because of their large size, they are rarely covered for methane capture. The removal of solids prior to entering the ponds would allow for shorter retention times resulting in smaller ponds that could be covered. However, removal of solids entails loss of organic material and thus methane production. It was proposed that improved hydrolysis of solid content prior to solids separation could increase the organic content of the liquid fraction. No literature was found describing two-stage (acidogenic/hydrolytic and methanogenic) systems which achieve hydrolysis combined with solids separation of manure slurries. Hence, the aim of the present study is to examine the feasibility of such a system. Five parameters were examined to determine favourable conditions for hydrolysis of solids and acidogenesis in farm dairy effluent. These were: 1) mixing, 2) hydraulic retention time (HRT), 3) liquid to solid ratio (dilution), 4) addition of rumen contents, and 5) reactor configuration. Continuous mixing of cow manure sludge inhibited net volatile fatty acid (VFA) production, likely due to oxygenation. By comparison, a once-daily brief stirring regime resulted in production of 785 mgVFA/Lsludge compared with 185 mg/L from a continuously stirred reactor. Mixing had little effect on soluble COD yield. HRTs ranging between 1 and 10 days resulted in greater hydrolysis yields (0.25 to 0.33 gCOD/gVSadded) compared with 0.15 gCOD/gVSadded for a 15-day HRT. It was hypothesised that the attachment of hydrolytic bacteria to solids prevented washout at shorter HRTs. In contrast, longer HRTs favoured VFA production. This may have been due to the planktonic nature of acidogenic bacteria, making them more vulnerable to washout at shorter HRTs. The effects of solid:liquid ratio on hydrolysis and acidogenesis were examined with sludge:water ratios ranging from 1:1 to 1:0.25. The addition of larger volumes of water resulted in improved acidogenesis with the 1:1 sludge:water mixture producing a liquor with 245% more VFA mass (635 mg) than reactors with a 1:0.25 sludge:water mixture (184 mg). Addition of rumen contents was shown to have little or no effect on either acidogenesis or hydrolysis. This may have been due to a masking effect of an increased organic load through the addition of undigested grass in the rumen. A mix, settle and decant (MSD) system and an unmixed flow-through leachbed separator system were trialled and compared as hydrolytic/acidogenic reactors. The MSD system produced 0.033gVFA/gTSadded and 0.315gCOD/gTSadded compared with 0.015gVFA/gTSadded and 0.155gCOD/gTSadded in the unmixed leachbed separator. It was hypothesised that improved mixing and longer solid-liquid contact times in the MSD system provided greater surface contact and transfer of organics to the liquid phase thereby enhancing hydrolysis. A two-stage (acidogenic/hydrolytic and methanogenic) system was tested at bench scale. A partially mixed leachbed separator was fed with manure slurry. This retained solids while leaching out a treated feed high in organic content to be fed into a variety of methanogenic systems. The leachbed separator produced a treated feed with a VFA concentration of 562 mg/L, 120% higher than the influent slurry (255 mg/L). Soluble COD increased 60% from 1,085 mg/L in the slurry to 1,740 mg/L in the treated feed. 20-day HRT and 10-day HRT unmixed unheated methanogenic reactors, both fed with treated feed from the leachbed separator, had lower specific methane yields (0.14 and 0.11 LCH4/gVS respectively) than a 50-day HRT reactor fed with untreated slurry (0.17 LCH4/gVS). However, both the 20-day HRT reactor and the 10-day reactor had higher volumetric methane yields (0.033 and 0.057 LCH4/Lreactor/day respectively) than the 50-day HRT reactor fed with slurry (0.024 LCH4/Lreactor/day). Gas production was shown to rise as the VFA levels in the treated feed rose. Fermentation in the leachbed followed by separation was shown to improve average gas production by up to 57% compared to separation alone. Field-scale trials of a leachbed separator system followed by a 20-day HRT methanogenic reactor were undertaken. VFA concentrations increased from 100 mg/l in the influent to 1,260 mg/l in the treated feed, while the soluble COD increased from 2,766 mg/L to 5,542 mg/L. The methanogenic reactor produced 0.08 m3 CH4/ m3reactor/day, four times higher than that which would be expected from a covered pond of the same size. This was hypothesised to be due to the increased biodigestability of the feed to the tank digester as well the increased organic loading rate. This study indicates that the use of a leachbed separator would be an effective low-tech strategy for reducing the HRT of farm anaerobic ponds, and reducing the size of covers required for biogas energy recovery.

The aim of this research was to investigate the feasibility of co-digestion of municipal primary sludge and whey by anaerobic CSTR (Continuous Stirred Tank Reactor), as well as the factors that affect the performance of the co-digestion reactors. Before studying the co-digestion process, a semi-continuous whey digestion experiment was conducted to analyze the feasibility of anaerobic digestion of whey along with pH control. The results obtained from the study indicated that supplement of nutrients, trace elements as well as heavy metals was necessary to maintain the anaerobic whey digestion system. To investigate the co-digestion of primary sludge and whey process, the effects of pH, OLR (Organic Loading Rate), HRT (Hydraulic retention time) as well as the COD (Chemical Oxygen Demand) loading ratio of primary sludge to whey on the performance of the reactors were studied. The results of the co-digestion experiments demonstrated that it was feasible to co-digest primary sludge and whey without nutrient, trace element and heavy metal supplement. The TCOD (Total Chemical Oxygen Demand) removal efficiency and the biogas production of the co-digestion system increased with the increase of OLR. At same OLR, digestion of the mixture of primary sludge and whey with higher whey content achieved higher biogas production and TCOD removal efficiency. The anaerobic co-digestion of primary sludge and whey process performed successfully at OLR of 5.8 ± 0.1g COD/l.d without pH control when the COD loading ratio of primary sludge to whey was approximately 70:30, due to the fact that the primary sludge may serve as buffering reagent. By adding sodium bicarbonate (NaHCO3) to maintain the pH at 6.9 ± 0.1, the OLR of the co-digestion reactor could reach 8.1 ± 0.1 g COD/l.d at HRT of 20 days. Moreover, by co-digestion of primary sludge and whey solution, the reactor could be operated successfully at HRT of 10 days and at OLR of 7.6 ± 0.1 g COD/l.d with COD loading ratio of primary sludge to whey of 53 : 47. The biogas production (3.2 ± 0.1 l/d) was 1.5 l/d higher than digestion of the same amount of primary sludge alone (1.7 ± 0.1 l/d).