Active Treatment System Research Articles

Evaluation of Characteristics of Sludge generated from Active Treatment System of Mine Drainage

Evaluation of Characteristics of Sludge generated from Active Treatment System of Mine Drainage

Removal of Manganese from Mine Drainages by the Passive Slag Reactor and Active Treatment System: Proposals for the Design of Treatment Facilities

망가니즈는 국내 광산배수에서 철에 이어 두 번째로 배출허용기준을 많이 초과하는 원소이나, 자연정화하기 어려워 그간 active 시설에서 처리해 왔다. 망가니즈 제거용 자연정화시설인 슬래그반응조가 도입 단계에 있으며, 이의 설계 인자들에 대하여 관련된 연구들로부터 제안하였다. 설계 인자는 필요 수위차, 매질 구성, 처리효율 변화, 그리고 체류시간을 포함한다. 또한, 기존의 active 처리시설에서 망가니즈가 철 및 알루미늄에 의해 공침 및 흡착 기작으로 제거되므로 처리를 위해 필요한 pH가 낮아지는데, pH 재조정조의 반영 여부 등을 판단해 효율적인 active 처리시설을 설계하기 위하여 Fe, Al 및 Mn 농도로부터 처리 pH를 추정하는 관계도 관련 연구로부터 제안하였다.

Assessment of metals mobility during the alkaline treatment of highly acid phosphogypsum leachates

This research evaluates the feasibility of an alkaline treatment system for highly acid leachates from a phosphogypsum stack located in an estuarine environment degraded by such pollution. The presented methodology consists of the addition of a Ca(OH)2 solution to the different types of phosphogypsum-related acidic leachates with the aim to increase their pH and subsequently, to provoke the precipitation and immobilization of the dissolved contaminants. In fact, phosphates and fluorides reached removal of 100% and 90%, respectively. As regards metals, removal values close to 100% were reached for Fe, Al, Cr, Cd, U and Zn, whereas it did not seem to be totally effective for other elements such as As (removal of 57–82%) and Sb (4–36%). The decrease of contaminant concentrations was caused probably by co-precipitation and/or adsorption to phosphate phases, together with by fluoride precipitation. The solid phases formed during the treatment were subjected to two standard leaching tests (EN 12457-2 from the EU and TCLP from the US) in order to conduct a risk and management assessment. In this context, some of the precipitates formed during the treatment would be classified as hazardous wastes, due to the high concentration of As leached. Moreover, the potential economic costs of a convectional active treatment system were also explored. This study sets the basis for a new research line with the aim to minimise the impact of the phosphogypsum stacks worldwide to their adjacent environment.

An emergy-based treatment sustainability index for evaluating waste treatment systems

The treatment of wastes can be accomplished using various combinations of natural processes and human invented technologies that operate by using a variety of energy sources and natural resources. In many waste treatment systems, the waste itself is used as a main energy source to drive treatment (e.g., activated-sludge in advanced wastewater treatment). Understanding the sustainability of waste treatment systems thus requires the capability for quantitatively comparing the energy and resource inputs with the waste-derived energy inputs and effluent quality. This study applied concepts of emergy accounting to develop a treatment sustainability index (TSI). The theoretical basis of the TSI is explained and then applied to two wastewater treatment systems—an operating passive treatment system and a hypothetical active treatment system for treating mine drainage in NE Oklahoma. The TSI accounts for renewable and purchased emergy inputs, the input of emergy from the wastewater itself, and the amount of work required by the receiving environment to further treat the effluent. Unlike other emergy-based indices, the TSI explicitly accounts for the energy provided by wastes, the waste treatment efficiency and the downstream effect on the releasing pollutants into receiving environments. Since the emergy associated with the waste used during treatment was orders of magnitude larger than renewable, non-renewable or purchased inputs, the TSI clearly captured the importance of accounting for waste emergy, and was able to quantify their sustainability. The TSI offers a new way to assess the sustainability of all types of treatment systems.

Emergy and Carbon Footprint Analysis of the Construction of Passive and Active Treatment Systems for Net Alkaline Mine Drainage

Multi-criteria sustainability assessments were completed for the construction of a net-alkaline mine drainage passive treatment system (PTS) in northeastern Oklahoma to compare resource use and greenhouse gas emissions with a hypothetical active treatment system (ATS) alternative. Emergy analysis, an environmental accounting method assessing resource use, and carbon footprint analysis, a tool to evaluate greenhouse gas emissions, were completed for the construction of both systems. Assessing sustainability using multiple criteria is important in evaluating systems on the basis of resource use and environmental impact. Construction of the hypothetical ATS required seven times more emergy purchased from the economy and emitted three times more carbon dioxide equivalents than construction of the PTS. Concrete was the largest factor in both the emergy analysis (ATS and PTS) and carbon footprint (ATS only). Diesel fuel was the largest factor in the carbon footprint of PTS construction. This multi-criteria sustainability assessment shows that a hypothetical ATS alternative to the PTS would have used more resources and emitted more greenhouse gases during construction.

Removal of metal from acid mine drainage using a hybrid system including a pipes inserted microalgae reactor

In this study, the microalgae culture system to combined active treatment system and pipe inserted microalgae reactor (PIMR) was investigated. After pretreated AMD in active treatment system, the effluent load to PIMR in order to Nephroselmis sp. KGE 8 culture. In experiment, effect of iron on growth and lipid accumulation in microalgae were inspected. The 2nd pretreatment effluent was economic feasibility of microalgae culture and lipid accumulation. The growth kinetics of the microalgae are modeled using logistic growth model and the model is primarily parameterized from data obtained through an experimental study where PIMR were dosed with BBM, BBM added 10 mg L(-1) iron and 2nd pretreatment effluent. Moreover, the continuous of microalgae culture in PIMR can be available. Overall, this study indicated that the use of pretreated AMD is a viable method for culture microalgae and lipid accumulation.

Problems and prospects connected with development of high-temperature filtration technology at nuclear power plants equipped with VVER-1000 reactors

Results of work on restoring the service properties of filtering material used in the high-temperature reactor coolant purification system of a VVER-1000 reactor are presented. A quantitative assessment is given to the effect from subjecting a high-temperature sorbent to backwashing operations carried out with the use of regular capacities available in the design process circuit in the first years of operation of Unit 3 at the Kalinin nuclear power plant. Approaches to optimizing this process are suggested. A conceptual idea about comprehensively solving the problem of achieving more efficient and safe operation of the high-temperature active water treatment system (AWT-1) on a nuclear power industry-wide scale is outlined.

Development of a kinetic model for biological sulphate reduction with primary sewage sludge as substrate

The Rhodes BioSUREÆÊ Process is a low-cost active treatment system for acid mine drainage (AMD) waters. Central to this process is biological sulphate reduction (BSR) using primary sewage sludge (PSS) as the electron donor and organic carbon source, with the concomitant reduction of sulphate to sulphide and production of alkalinity. To optimise the design, operation and control of (and research into) BSR with PSS, a mathematical kinetic model would be an invaluable aid. This study describes the development of such a kinetic model. A two-phase (aqueous/gas) physical, biological and chemical processes kinetic model for the methanogenic anaerobic digestion of sewage sludges has been proposed (UCTADM1). This model incorporates biological processes for sewage sludge hydrolysis/solubilisation (usually the rate-limiting step) and acidification, acetogenesis, and acetotrophic(clastic) and hydrogenotrophic methanogenesis. Additionally, the background weak acid/base chemistry for water, carbonate, acetate, propionate, ammonium and phosphate species have been included, as well as the physical gas exchanges for carbon dioxide and ammonia. The compound H+ is explicitly included in the model as a predictive parameter, with corresponding pH inhibition of the methanogenic bioprocesses. Using this model as a basis, it is extended to incorporate BSR. The stoichiometry and kinetics for the bioprocesses (growth and death) mediated by the propionate degrading, acetotrophic and hydrogenotrophic sulphate-reducing bacteria are formulated, including sulphide and pH inhibition. These bioprocesses produce and consume inter alia sulphate and sulphide acid/base species which are not present in the original UCTADM1 model. Accordingly, following the approach in the UCTADM1 model, chemical processes for these are included. Further, in the BSR model the end-product sulphide has a gaseous equilibrium not in the UCTADM1 model, and hence the physical gas exchange for sulphide is included. The BSR biological, chemical and physical processes are integrated with those of the UCTADM1 model, to give a complete kinetic model for competitive methanogenic and sulphidogenic anaerobic digestion with PSS as substrate. This model currently is being evaluated, by application to a series of experimental systems fed a mixture of PSS and sulphate, operated over a range of retention times and pHs.

Estimating diesel degradation rates from N2, O2 and CO2 concentration versus depth data in a loamy sand

SummaryThe degradation rate of the pollutant is often an important parameter for designing and maintaining an active treatment system or for determining the rate of natural attenuation. A quasi‐steady‐state gas transport model based on Fick’s law with a correction term for advective flux, for estimating diesel degradation rates from N2, O2 and CO2 concentration versus depth data, was evaluated in a laboratory column study. A loamy sand was spiked with diesel fuel at 0, 1000, 5000 and 10 000 mg kg−1 soil (dry weight basis) and incubated for 15 weeks. Soil gas was sampled weekly at 6 selected depths in the columns and analysed for O2, CO2 and N2 concentrations. The agreement between the measured and the modelled concentrations was good for the untreated soil (R2= 0.60) and very good for the soil spiked with 1000 mg kg−1 (R2= 0.96) and 5000 mg kg−1 (R2= 0.97). Oxygen consumption ranged from −0.15 to −2.25 mol O2 m−3 soil day−1 and CO2 production ranged from 0.20 to 2.07 mol CO2 m−3 soil day−1. A significantly greater mean O2 consumption (P < 0.001) and CO2 production (P < 0.005) over time was observed for the soils spiked with diesel compared with the untreated soil, which suggests biodegradation of the diesel substrate. Diesel degradation rates calculated from respiration data were 1.5–2.1 times less than the change in total petroleum hydrocarbon content. The inability of this study to correlate respiration data to actual changes in diesel concentration could be explained by volatilization, long‐term sorption of diesel hydrocarbons to organic matter and incorporation of diesel hydrocarbons into microbial biomass, aspects of which require further investigation.

Treatment of Acid Sulfate Soil Drainage By Direct Application of Alkaline Reagents

Due to the episodic nature of rainfall and the high dissolved metal concentrations in the acid sulfate soil catchment of Clothiers Creek (NSW, Australia), active treatment was considered more appropriate than passive treatment. Alkaline reagents were added to oxidised shallow drains to remove acidities ranging from 438 to 1,837 mg/L CaCO3. A fine limestone slurry was produced from the pounding together of limestone rock fragments within a rotating drum and, on addition to drain waters, was found to remove acidity to varying degrees of effectiveness (from 12 to 100%). The efficiency decreased as the pH of the water approached neutrality due to calcite saturation and the slow reaction rate of limestone at high pH. Hydrated lime powder was also mixed with drain water in the rotating drum though most mixing occurred once the slurry entered the drain where efficiencies ranging from 67 to 89% were observed. A powdered mixture of MgCO3 and CaCO3 was only 11% effective in treatment of the drainage water due to the slow rate of reaction of MgCO3. Whilst the active treatment system was capable of treating a large acidity flux (particularly using hydrated lime) it required regular addition of reagent and the dosing of hydrated lime was particularly difficult to control. Future designs of this active treatment system should be automated to prevent adverse aquatic impacts due to overdosing.

An overview of the fan active noise control effort at NASA, Lewis

NASA, Lewis began an effort, several years ago, in the area of fan tone active noise control. This effort was part of the Advanced Subsonic Transport Program. The effort consists of two parts: (1) building a test facility (the active noise control fan) to allow proof of concept testing, and (2) a contract effort to bring several concepts to the test phase. This paper will describe the test facilty and its unique capabilities such as a continuously rotating rake to measure the complete modal structure of the fan tones. Concepts tested will be described and the test results will be briefly discussed. All the concepts involve modal control. The concepts range from a single wall actuator array to control a single radial mode order, to multiple orders in both inlet and exhaust ducts using active vanes. In addition, a hybrid system (active+passive elements) and active treatment system will be presented. The performance of these systems will be discussed in terms of mode and tone total power reduction.

Iron precipitation kinetics in synthetic acid mine drainage

To evaluate the design and operation of a new active treatment system for acid mine drainage (AMD), the behavior of ferric iron solutions after the addition of bicarbonate ions was investigated. The effects of various other factors common to AMD on the precipitation rate of iron were also studied. It was found that the rate of Fe III precipitation in synthetic AMD was not affected by the presence of Al or Mn, within the concentration ranges investigated (for Al, 0-0.01 M, for Mn, 0-0.002 M). Our experiments showed that the induction time (tmd),i.e., the time elapsed between the addition of base ions and the detection of iron precipitation, decreased with increasing iron concentration and pH but increased with increasing sulfate concentration: log tind=6.7(±0.30)−1.29 (±0.10) pH+0.94(±0.07) log [SO4]−0.36 (±0.05) log [Fe] Our results suggested that sulfate sorbed to the surface of growing iron oxyhydroxides, inhibiting their growth. This effect offers an important tool that can be used to control the precipitation of iron in AMD treatment facilities.