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In recent years, the rapid development of the rare earth industry has had a serious impact on the environment. Some enterprises have taken measures to improve the production process. In order to explore the sustainability of this industry and these improvements’ environmental benefits, this paper combines emergy analysis and lifecycle assessment to evaluate and compare the production process of rare-earth oxides considering the three aspects of emergy flow, pollutant emissions, and emergy-based indicators. Changes in the emergy of pollutant emissions before and after improvement of the production process are discussed. The results show that the greatest inputs in the mining and beneficiation stage and smelting separation stage are labor force and service and non-renewable resources, respectively. These two production stages are highly dependent on external input and have weak competitiveness. Both stages place great pressure on the environment, so the bastnasite production process would be unsustainable in the long term. After the improvement, the environmental impact of the production process for bastnaesite changed significantly, indicating that the improvement effect of the wastewater treatment facilities and the change of fuel from coal to natural gas is remarkable.

Environment-friendly treatment of sewage sludge has become tremendously important. Conversion of sewage sludge into energy products by environment-friendly conversion process, with its energy recovery and environmental benefits, is being paid significant attention. Direct liquefaction of sewage sludge into bio-oils with supercritical water (SCW) was therefore put forward in this study, as de-water usually requiring intensive energy input is not necessary in this direct liquefaction. Supercritical water may act as a strong solvent and also a reactant, as well as catalyst promoting reaction process. Experiments were carried out in a self designed high-pressure reaction system with varying operating conditions. Through orthogonal experiments, it was found that temperature and residence time dominated on bio-oil yield compared with other operating parameters. Temperature from 350 to 500°C and reaction residence time of 0, 30, 60min were accordingly investigated in details, respectively. Under supercritical conversion, the maximum bio-oil yield could achieve 39.73%, which was performed at 375°C and 0min reaction residence time. Meanwhile, function of supercritical water was concluded. Fuel property analysis showed the potential of bio-oil application as crude fuel.

Abstract A great deal of heat is wasted in intensive public shower facilities, such as those in schools, barracks and natatoriums, which open up at specified time. It will contribute a lot to energy saving and environmental protection with significant economic benefits to recycle the exhaust heat. In this paper, we propose two different kinds of heat pumps (an electric heat pump and an absorption heat pump) in the heat recovery systems. In both system, the used shower water is drained through a pipe and collected in a gray water pool. When the wastewater reaches certain volume, the heat pump system will begin working and recycling heat. The wastewater is filtered and piped to the heat exchanger to exchange heat with the tap water whose temperature will increase from 12 °C to 25 °C with the wastewater temperature dropping from 30 °C to 17 °C. Then the wastewater is piped to the heat pump evaporator and the tap water is piped to the condenser for farther heating. According to the different characteristics of the electric heat pump and absorption heat pump, we also introduce the processes and control methods of different heat recovery systems in details in this paper. Based on a practical example, this paper analyzes and compares the economic and environmental benefits of three retrofitting schemes, including “exhaust heat recovery using electric heat pump”, “exhaust heat recovery using electric heat pump + gas boiler” and “exhaust heat recovery using direct-fired heat pump”. Then we find out that the heat recovery system using direct-fired absorption heat pump has lower energy consumption, less pollution, lower operating cost, and shorter payback period. And it has a promising practical application.

In this study, levulinic acid (LA) was produced from rice straw biomass in co-solvent biphasic reactor system consisting of hydrochloric acid and dichloromethane organic solvent. The modified protocol achieved a 15% wt LA yield through the synergistic effect of acid and acidic products (auto-catalysis) and the designed system allowed facile recovery of LA to the organic phase. Further purification of the resulting extractant was achieved through traditional column chromatography, which yielded a high purity LA product while recovering ∼85% wt. Upon charcoal treatment of the resultant fraction generated an industrial grade target molecule of ∼99% purity with ∼95% wt recovery. The system allows the solvent to be easily recovered, in excess of 90%, which was shown to be able to be recycled up to 5 runs without significant loss of final product concentrations. Overall, this system points to a method to significantly reduce manufacturing cost during large-scale LA preparation.

The development of advanced computational models for improving the accuracy of streamflow forecasting could save time and cost for sustainable water resource management. In this study, a locally weighted learning (LWL) algorithm is combined with the Additive Regression (AR), Bagging (BG), Dagging (DG), Random Subspace (RS), and Rotation Forest (RF) ensemble techniques for the streamflow forecasting in the Jhelum Catchment, Pakistan. To build the models, we grouped the initial parameters into four different scenarios (M1–M4) of input data with a five-fold cross-validation (I–V) approach. To evaluate the accuracy of the developed ensemble models, previous lagged values of streamflow were used as inputs whereas the cross-validation technique and periodicity input were used to examine prediction accuracy on the basis of root correlation coefficient (R), root mean squared error (RMSE), mean absolute error (MAE), relative absolute error (RAE), and root relative squared error (RRSE). The results showed that the incorporation of periodicity (i.e., MN) as an additional input variable considerably improved both the training performance and predictive performance of the models. A comparison between the results obtained from the input combinations III and IV revealed a significant performance improvement. The cross-validation revealed that the dataset M3 provided more accurate results compared to the other datasets. While all the ensemble models successfully outperformed the standalone LWL model, the ensemble LWL-AR model was identified as the best model. Our study demonstrated that the ensemble modeling approach is a robust and promising alternative to the single forecasting of streamflow that should be further investigated with different datasets from other regions around the world.

Summary Monitoring of microbial corrosion is always difficult because of the sessile nature of bacteria and the lack of meaningful correlation between routine bacteria counts and bacterial activity. This problem is further aggravated in a large oilfield water system because of size and sampling difficulties. This paper discusses some monitoring techniques currently used in the oil industry, their limitations, and possible areas for improvement. These improved techniques are in use or will be implemented in the Aramco systems. Introduction Microbial corrosion has caused some failures in seawater injection systems. Whether or not microbial corrosion represents a major corrosion mechanism in the oilfield water system is a controversial question. However, it has certainly become a major concern in recent years. There are two approaches in dealing with microbial corrosion problems in a large oilfield water system. One approach is to start treating the system with bactericide in conjunction with regular scraping when the system is commissioned. The other is to treat the system only when an impending microbial-related problem is clearly defined. in either case, monitoring of microbial corrosion is essential. The first approach is more or less a precautionary measure. The treatment and selection of bactericides is usually based on past experience and laboratory evaluation tests. While the treatment is being implemented, a reliable monitoring program could assess the effectiveness of the current program of microbial corrosion control. In the second case, monitoring of microbial corrosion is even more important. it would provide timely information toward implementation of a treatment program before the system could get out of control. The industry's awareness of microbial corrosion has been indicated by the number of papers published in recent years on this subject. These articles cover a wide spectrum of interest from fundamental corrosion mechanisms to case studies, detection methods, control measures, etc. Although it is not clear to what extent microorganisms are responsible for the observed field corrosion failures, the general consensus still favors early establishment of a routine microbial corrosion monitoring program. The best approach seems to he the establishment of solid baseline data for the system after which any significant future deviation can be interpreted as a sign of a potential problem. The following sections describe the current methods used for routine monitoring, specifically for Aramco's large oilfield water systems. The limitations of these methods, the difficulties encountered, and some suggested studies for modification and improvement are discussed also. Current Monitoring Methods The methods currently used by Aramco can be categorized as (l) cell counts in water, (2) metal surface examination, (3) scraping solids analysis, (4) water quality analysis, and (5) evaluation of current bactericide treatment. Cell Counts in Water. These are used to detect bacterial organisms and their concentrations. it is recognized that confirmation of free-flowing bacteria in the water does not automatically mean trouble. However, if bacteria counts demonstrate a definite increase across the system, or over a period of time, the odds are that bacteria are active and working on the metal somewhere in the system. Cell counts routinely monitored include sulfate-reducing bacteria (SRB), general aerobic bacteria (OAB), iron bacteria, and others. SRB are widely recognized to he primarily responsible for bacteria-induced corrosion in an anaerobic environment. Depending on the nature of the sample to be tested and the types of problems encountered (or expected) in the field, one or several different enumeration techniques are employed. For field work, the method generally used by Aramco is culturing of samples in liquid growth media specifically designed for detecting a certain group of organisms. These laboratory media are prepared using the appropriate field water as a base, with addition of general growth nutrients for the organisms. The use of field water to prepare the media provides a water composition similar to that in which the bacteria originated. The media are supplemented with other ingredients to create an environment conducive to growth of certain bacteria (e.g., certain reducing agents have to he added into the SRB media). The media then are dispensed into serum vials at exactly 9 mL [9 cm3] each and sealed with rubber stoppers and aluminum seals. JPT P. 1171

The cover of a disposal cell is an important element in the long-term stability of a reclaimed uranium tailings site. The cover is generally comprised of a radon barrier, filter, and surface erosion barrier. A study is conducted to investigate the drainage and erosion potential between the filter and radon barrier layer in response to surface water flows over a layer of riprap. A cover system is physically modeled in a hydraulics laboratory. The experimental program evaluated the interstitial velocity potential through four filters, the erosion and sediment transport potential from the radon barrier, and the filter drainage rate after passage of the surface runoff hydrograph. The results indicated that the use of traditional filter criteria to bed riprap is extremely conservative and restricts drainage. The grain size of the filter materials should be increased to enhance drainage when placed on flat (\IS\N ≤\N 5%) slopes. A relationship is presented for estimating the drainage velocity potential through a filter layer as a function of slope and gradation. A new filter criteria should be developed for overtopping flow conditions.

Abstract A new formulation for the evaporation, flashing, condensation processes taking place in the effects of thermal desalination systems which simulates the operation of both forward and parallel/cross configurations is coupled with an exergo-economic model based on the SPECO method. The thermo-economic model uses accurate properties for the seawater, brine, pure water and vapour and is solved with an equation solver which does not require the development of a specific solution algorithm as in most previous studies. This flexible model is used to analyze the influence of the number of effects N and the temperature difference ΔT e between effects on the technical and economic performance of multi-effect desalination systems with ejector vapour compression. In particular, it is shown that the performance calculated by an earlier black-box approach is not attainable by technically and economically realistic systems. It is also shown that for each feed configuration and a given number of effects there exists an optimum value of ΔT e which minimizes the cost of the produced potable water. This last result forms the basis of a procedure that combines black-box results with the optimum value of ΔT e and can be used to select the appropriate system for any specific application.

Abstract The Permian Basin in West Texas contains one of the thickest deposits of Permian rocks found anywhere in the world. The Embar-B lease located in southern Andrews County on the Central Basin Platform (a regional structural high in the Permian Basin) has been producing from the Leonardian Clearfork formation for over 70 years. The Clearfork formation is primarily a subtidal and intertidal carbonate rock characterized as moderate quality reservoir. Most Permian Basin fields have multiple stacked reservoirs with varying degrees of reservoir quality and there is typically a need in these maturing fields to increase reservoir contact. In 2009, a drilling campaign was launched in Embar-B with a focus on expanding the completion interval to include what was previously considered marginal pay in the deeper Wichita Albany formation. The Wichita Albany, also Leonardian in age, is composed mostly of marginal quality tidal flat rocks and is characterized by high fracture gradients and low permeability. These characteristics required an advancement in completion practices to achieve a successful stimulation. The combination of improved completions practices and an expanded target interval resulted in production double that of previous wells. This success has driven a need for an innovative development strategy and continued optimization of completion practices. Geomodeling, volumetrics, reservoir simulation, seismic attribute analysis and oil fingerprinting were all used for reservoir characterization and to determine an allocation method for commingled wells. This lead to the identification of several Clearfork/Wichita Albany locations with significant reserves potential. Re-evaluation of the completion strategy using a multidisciplinary approach indicated the need to reduce the number of perforation clusters, add a diversion mechanism, and develop multiple hydraulic fracturing designs based on reservoir quality and presence of natural fractures. Results from recent drilling programs have exceeded expectations bringing lease production up from 200 BOEPD in 2009 to a peak rate of 3153 BOEPD in 2015.