Application of infrared ATR spectroscopy to in situ reaction monitoring

The infrared horizontal ATR technique was adapted to be applied for in situ reaction monitoring even at high pressure and high temperature. Different types of reactors and flow cells were built which can be used for recording IR ATR spectra at pressures up to 200 bar and temperatures up to 300°C.

The use of the horizontal ATR technique is shown by the following application examples:

• addition reaction of n-butyl isocyanate with butyric alcohol;

• investigation of the equilibrium of isocyanate, HCl and carbamic acid chloride at elevated pressure and temperature;

• monitoring the polycondensation of bifunctional alcohols and carbonic acids;

• recording spectra of polymer melts at 280°C.

Implementation of ISO 14001:2004 (environmental management system standard) for reverse osmosis desalination plants for the first time in Iran

Implementation of ISO 14001:2004 (environmental management system) has been executed for reverse osmosis desalination plants for the first time in Iran at Noor Vijeh Company (N.V. Co), a water and wastewater firm based in Tehran. The scope of work was the activities and product of company's BWRO desalination plant in the city of Qom (3000 m³ per day) and SWRO desalination plant in Assaluyeh, Pars Special Economic and Energy Zone, Iran. The aims of this project were in line with company’s approach to sustainable development and its direction towards conducting environmental friendly activities and production characteristics.

Initially the famous PDCA (Plan, Do, Check, Act) was used to identify the aspects and evaluate their effects. The significant aspects of each plant affecting the environment are then identified and preventive control measures and reducing their probabilities of loss are anticipated. These cover the normal activities within each plant and those aspects arising from emergency conditions such as earthquakes, fire, etc.

Elements of this system are

• Environmental policy and its targets and programmes

• Practical methods for environmental management system processes

• Executive manuals for implementing special activities

• Tables and indexes for environmental aspects for each plant

• Organizational charts, positions, qualifications, and necessary trainings for the involved personnel.

Environmental aspects are evaluated through their interaction with and effects over, releases to water, emissions to air, land contamination, waste management, energy use, and use of natural resources and raw material.     

Heterogeneous catalysis: looking forward with molecular simulation

Some of the areas in which we anticipate, over the next five years, notable advances in the application of molecular simulation to problems in heterogeneous catalysis are considered, in the context of recent progress to date. The areas specifically addressed are:

• expanding access to methods,

• quantitative structure-property relationships,

• building structural models to focus or pre-screen experiments,

• confidence in predicting local and extended structure

• reaction mechanisms, barriers and kinetics, and

• data for chemical process simulations.

In each of these areas, we indicate why we consider the topic significant, provide reference to topical work and suggest opportunities for future developments.     

A new look at dual purpose, water and power, plants - economy and design features

In light of rapidly rising equipment and fuel costs, recent studies have shown some important results in the economy and optimum designs for dual purpose power/desalting complexes. The desalination cycle chosen for- detailed comparisons in this study is the well known multistage flash (MSF) evaporator, which uses brine recirculation and polyphosphate scale prevention. The multi- stage flash evaporator has found wide spread application in large plants throughout the world. Single units of up to 1400 m3/hr (9.5 MGD), acid dosing, have been built and are now in operation. In general due to corrosion problems, polyphosphate plants are now preferred over the acid one.

A number of schemes for the combined production of power and. water were chosen, mainly a combination of MSF Unit with each of the following power cycle:

• 1- Automatic extraction steam turbine

• 2- Simple gas turbine with waste heat boiler

• 3- Back pressure steam turbineThis paper presents a study of the economic aspects, thermodynamic features and optimization analysis of each of these combined power and water production plants.

The optimum value of the performance ratio and its effect on reducing the cost of water in each of the above mentioned schemes would be discussed in this paper.     

Teaching and learning strategies and evaluation changes for the adaptation of the Chemical Engineering degree to EHES

An integrated learning methodology has been developed and implemented in order to adapt the Chemical Engineering degree in the University of Valladolid (Spain) to the European Higher Education Space (EHES) philosophy. It was necessary to modify the objectives and theoretical contents of the different subjects and also the learning methodology, considering the general chemical engineering skills and also the transferable skills reached by the students, according to the recommendations of the European Federation of Chemical Engineering (EFCE) for chemical engineering education in Bologna two-cycle degree system.

This methodology has been applied to the seventh semester of a 5 years Chemical Engineering degree. The main objectives of the proposed strategy were:

• To provide to the student with a holistic, integrated and applied vision of the different subjects involved in chemical engineering, coordinating all of them and planning common activities as a case study based on an industrial process.

• To help students to develop transferable skills by means of designing suitable teaching and learning strategies.

• To prepare the students for the long-life learning.

General and particular objectives were defined adapting the course to the EHES philosophy. In this sense, the programmes in terms of the learning outcomes and competences to be acquired were designed, the total student workload to get the objectives of the programme was estimated and the entire course was programmed and planned in a detailed schedule. A course guide was elaborated including all this information, resulting in a useful instrument for teachers and students.

This methodology was complemented with the evaluation of the global learning process. The evaluation made was based on the next two aspects:

• Student learning evaluation. Tutorial sessions, written reports, oral presentations, discussion sessions and partial and final written exams were considered.

• Learning methodology evaluation. External evaluation requires carrying out inquiries, both to students and teachers involved.

Control of organic fouling at two seawater reverse osmosis plants

Organic fouling of seawater Reverse Osmosis (RC) membranes is a phenomenon not well understood; it can result in a loss of membrane productivity and salt rejection properties. Two seawater RO plants using DuPont B-10 hollow fiber permeators had experienced organic fouling and were studied.The two plants used different sources of feedwater; one RO plant at Culebra, Puerto Rico, used open seawater; while the other RO plant at Grand Cayman Island, British West Indies, used a sea well. Both feed water sources possessed high concentrations of soluble organics (40–80mg/1) which were mainly humic acids. In an attempt to remove these organics with in-line cationic polyelectrolyte coagulation, the plants experienced organic fouling which caused excessive loss of productivity and salt rejection; both plants initially failed their acceptance tests.It was discovered that the fouling was actually caused by interactions between the humic acids and in-line cationic, polyelectrolyte coagulants which were not removed by in-dedth and cartridge filtration. Rather than remove the humic acid material, acid addition was initiated and in-line cationic coagulants use discontinued to keep the humic acids soluble. It should be noted that with the open seawater intake ferrous sulfate was still used to remove colloidal material and reduce the SDI. Both plants subsequently have passed their 720-hour acceptance test.Culebra and Grand Cayman plants have now exceeded design specification for both productivity and salt rejection. The aramid hollow fiber permeators on acidified feed have shown 100% rejection of these organics at both 25% and 50% conversion and organic fouling has not been evident.     

Enhancement of media filter performance with coagulant use for treatment of diesel oil contaminated surface water

The objective of this study was to investigate the effect of coagulant addition on the filter performance and effluent quality during media filtration of surface water contaminated with diesel oil. A pilot scale multi-media filter system was operated under constant head conditions and at a constant loading rate of 30 L/min. The tests were conducted with and without coagulant addition prior to filtration of the surface water contaminated with diesel oil. Each filtration run was continued until the pressure drop increased to 0.7 bar. The source water with a turbidity of 10-15 NTU was prepared by mixing bentonite clay with tap water. The effect of coagulant addition on the performance of a multi-media filter for treatment of diesel oil contaminated source water was evaluated based on pressure change, filter run time before the filter clogged, and turbidity removal. The coagulant addition significantly improved the operational time of the media filter by reducing the rate of clogging. Both turbidity and PHC removal was achieved during the runs with coagulant addition.     

Sea water desalination by reverse osmosis in chigasaki laboratory

For the purpose of constructing a reverse osmosis [RO) sea water desalination plant of 800 m³/day capacity, a series of tests on the following themes have been carried out in the Chigasaki Laboratory:

1. Performance and durability of 8B modules made in Japan

2. Simplification of pretreatment system

3. Establishment of energy recovery system.

Domestic modules showed good and stable performance during long term operation, and water recovery ratio of these modules have been raised to 40%.

In-line coagulation and filtration system has been established for the pretreatment of feed sea water, instead of coagulation, sedimentation and filtration system.

The energy recovery equipment is consisted of a high-pressure pump, a motor and a hydraulic turbine on a common base. Recovered energy from pressurized brine is used for the auxiliary motive power of the high-pressure pump. The experimental data show that about 20% of required power for the pump was recovered.     

Two seawater reverse osmosis plants operating at high pressure and 50% conversion

At the Second World Congress on Desalination and Water Re-Use (Bermuda) an evaluation was made on a Reverse Osmosis (RO) plant operating at high pressures (1100-1500 psig) using Middle East conditions; it was concluded that such an RO plant could obtain 50 percent conversion of the feedwater and incur lower capital and operating costs.Two RO seawater plants using DuPont B-10T hollow fiber permeators were studied; these plants, one a 400m³/day facility and the other a 115m³/day facility, were designed for 50% conversion at a maximum 1200 psig operating, pressure. The plants used direct one to one brine staging and have operated at 1140 psig since their start-up.These plants have continually exceeded design specifications for both productivity and salt rejection. Both the first and second stage permeators combined have maintained 50% conversion with a TDS of the product water less than 350 ppm. These hollow fiber aramid permeators have maintained excellent performance at high pressure despite the fact that the feedwater possessed a very high concentration of organics (humic acid).The capital and operating costs of this plant have been significantly less than that of a comparable RO plant using lower pressure (900 psig). The performance data and cost analysis of this high pressure RO plant support the hypothesis that high pressure RO can provide excellent performance at a lower cost.     

The malta seawater RO facility

The Polymetrics seawater reverse osmosis (RO) facility at Ghar Lapsi, Malta, is one of the largest seawater RO plants in the world, with an installed capacity of 20,000 m³ /d (5.3 U.S. mgd). A second plant, provided under the same contract, has a capacity of 4,500 m³ /d (1.2 U.S. mgd), utilizing highly brakish feedwater. The plants supply potable water for the island's 350,000 residents and its growing tourist trade.The seawater plant is a single pass design, utilizing DuPont permeators and is the first major installations incorporating energy recovery turbo-pumps.This paper summarizes the plant design, manufacture, assembly, and installation, and also reports up-to-date operation and maintenance data. The operating costs are presented.     

Optimization of PACl dose to reduce RO cleaning in an IMS

In order to ensure stable treated water quality and to reduce chemical costs in any treatment plant it is necessary to study and optimize the coagulant dosing control (CDC). This research focused on the affects of coagulant in the integrated membrane (UF & RO) system employed for industrial water production. The dose of coagulant (PACl) might be associated (partly) with the frequency of cleaning in the RO units, and a value of 20 abs/m in the UF permeate is the control of the dosage process. This could suggest that organic fouling is directly and indirectly (inducing biofouling as well) the cause of fouling of the RO membranes. Nevertheless, high doses of PACl could produce scaling of aluminium and, in this work minimizing PACl to prevent operational problems in RO membranes was focused.

The approach involved the study of the treatment processes, determination of the optimum dose of coagulant, evaluation of the removal efficiency of UV and DOC by coagulation. The available data, which comprised monthly/weekly measurements for a period of six years of operation, was studied and analyzed and an attempt was made to draw some conclusions for the plant regarding the coagulant dosage and the link with UV absorbance as control.

The study of the coagulant dosing control revealed that the use of simple and robust online sensors like UV measurement allows an automatic dosing control although this parameter is not found to be sufficient to fully characterize nor predict fouling during membrane operation and there is no link between UV after the UF and the cleaning frequency of the RO. Parameters, as the added value allowed to verify the doses efficiencies in UV and DOC removal. Coagulant dose depends on the level of UV absorbance in the UF permeate and it should never be higher than 20 abs/m to ensure a RO cleaning frequency as long as possible. However, it was found that the target value of 20 abs/m produced substantial over dose of coagulant — 90% of the time – when UV removal is considered only. In the same way, for coagulant doses in excess of 5 mg/L, the additional removal of UV is less than 2.5% per mg coagulant/L, which suggests that the current dose is on the high side.

Furthermore, a coagulant dose in excess of 5 mg/L did not produce significant additional UV removal, and thus a reduction from 14 mg/L (2005 dose) to ca. 7 mg/L could be considered.     

Palm oil mill effluent pretreatment using Moringa oleifera seeds as an environmentally friendly coagulant: laboratory and pilot plant studies

This research paper covers the suitability of the coagulation–flocculation process using Moringa oleifera seeds after oil extraction as a natural and environmentally friendly coagulant for palm oil mill effluent treatment. The performance of M. oleifera coagulant was studied along with the flocculant KP 9650 in removal of suspended solids, organic components and in increasing the floc size. The optimum values of the operating parameters obtained from the laboratory jar test were applied in a pilot‐scale treatment plant comprised of coagulation–flocculation and filtration processes. Pilot‐scale pretreatment resulted in 99.7% suspended solids removal, 71.5% COD reduction, 68.2% BOD reduction, 100% oil and grease removal and 91% TKN removal. In pilot plant pretreatment, the percentage recovery of water was 83.3%, and 99.7% sludge was recovered after dewatering in a filter press. Copyright © 2006 Society of Chemical Industry     

水淬渣处理电厂生活污水的试验研究

通过石英砂和水淬渣单层滤料的对比试验,了解水淬渣的过滤性能.并采用水淬渣-石英砂双层滤料不加药直接过滤技术对电厂生活污水二级出水进行深度处理.试验结果表明:在去除浊度方面,水淬渣和石英砂的过滤性能相差不大;在去除COD方面,水淬渣的过滤性能优于石英砂.滤速为7.5 m/h时,水淬渣-石英砂滤料的平均出水浊度＜3 NTU、COD＜15 mg/L,满足回用标准,出水水质稳定.     

Using SDI,SDI+ and MFI to evaluate fouling in a UF/RO desalination pilot plant

This paper assesses the performance of a UF/RO demonstration plant located in the Oosterschelde estuary in the south-western part of the Netherlands. Spring blooms in the seawater pose a challenge to the plant because of the resulting increased fouling potential of the water. Determinations of the fouling indices SDI, SDI⁺ and MFI0.45 were carried out at the plant with different operational conditions, such as of coagulant addition and pH correction. Eight different membranes were used in the tests. In general, the UF performance was found to be good as the SDI values were around 1, provided standard membranes were used, and the MFI0.45 values lower than 1 s/L². The MFI0.45 showed the same tendency as the SDI in most cases. As expected, whereas the SDI showed marked sensitivity to used membrane type and operational conditions, the SDI⁺ did not display this dependency and hence appear to be a more reliable fouling index than the SDI. Storing the RO feed overnight in the feed tank increased the fouling potential of the RO feed, likely caused by continued coagulation.     

Evaluation Of Ozone/Biological Treatment For Disinfection Byproducts Control And Biologically Stable Water

Impacts of ozonation followed by biological filtration on the formation of disinfection byproducts and the production of biologically stable water were studied on pilot plant and full-scale at two U.S. locations (Oakland, CA and Tampa, FL). Also evaluated is a method to estimate bacterial regrowth potential by comparing it to assimilable organic carbon (AOC) measurements. At both locations, settled plant water is diverted to the pilot plant where it is split into two parallel trains. One train is ozonated, then Filtered through anthracite/sand dual media followed by GAC or through a GAC/sand dual media filter. The other train (control) is identical except that the water is not ozonated. The full scale plants have sedimentation, ozonation, then GAC/sand filtration.     

Performance evaluation of BWRO desalination plant — A case study

Fouling and scaling are the most serious problems in membrane processes. In sea/brackish water applications, pretreatment of RO feed water is the key step in designing the plants to avoid membrane fouling and scaling. Recent developments in pretreatment processes are more adapted to raw water quality. But, in some cases, raw water quantity/quality varies during seasons and is also influenced by the environment. Thus, pretreatment design becomes complicated and should cope with the raw water quality changes. The success of such operation requires qualified operators who will be able to adapt with different situations. Surface and brackish water sources are mostly facing these problems. In this paper, performance evaluation carried out for a brackish water reverse osmosis (BWRO) plant located in the west of Algeria is presented. This plant showed poor performance after a few months of operation. The operating pressure and pressure drop increased significantly without an increase in the production capacity and the permeate conductivity decreased surprisingly. Frequent shutdowns of the plant were observed due to severe membrane fouling. To identify the causes for the poor performance, different investigations were carried out. Membrane autopsy was performed and chemical analyses of foulants on the membrane surface by scanning electron microscopy were carried out to identify the matters responsible for fouling. The results showed that the quality of raw water changed widely due to drying of some wells and decrease of the water level in other wells. RO membranes were fouled by inorganic matters mainly colloidal/particulate silica and fine particles of clay present in raw water. Thus, the pretreatment scheme was thoroughly reviewed to find out why suspended solids were not removed by the sand and cartridge filters even though SDI was always less than 1. The problem was resolved by injecting a coagulant before the sand filters.     

On the reduction of desalting energy and its cost in Kuwait

All seawater desalting processes, multi-stage flash (MSF), multi-effect boiling (MEB), mechanical vapor compression (MVC) and seawater reverse osmosis (SWRO) consume significant amounts of energy. The recent increase of fuel oil cost raises the cost of energy consumed for desalting water and the final water cost, and creates more interest in using more energy efficient desalting systems.

The most used desalting systems by distillation (MSF and MEB) are usually combined with power plants in what is called co-generation power desalting plants, CPDP. Fuel is supplied to the CPDP to produce both desalted water D and power W, and the fuel cost is shared between D and W. Exergy analysis and equivalent work are among the methods used to determine the fuel energy charged to each product. When desalting systems, such as SWRO and MVC, are not combined with a power plant, the fuel energy can be directly determined from its electrical power consumption.

In this paper, the fuel energy cost charged to desalting seawater in the presently used CPDP in Kuwait is calculated based on exergy analysis. The MSF, known by its high energy consumption, is the only desalting method used in Kuwait. The MSF units consume 258 kJ/kg thermal energy by steam supplied to the brine heater BH, 16 kJ/kg by steam supplied to steam ejectors, and 4 kWh/m3 mechanical energy for pumping. These MSF units are operated either by:

(1) Steam extracted from extraction/condensing steam turbines EC/ST as in as in Doha West, Azzour, and Sabbiya CPDP. This practice is used in most Gulf area.

(2) Steam supplied directly from boilers as occurred in single purpose desalting plants as Al Shuwaikh plant; or in winter time when no steam turbines are in operation in the CPDP to supply steam to the desalting units.

The CPDP have limited water to power production ratio. While they can cope with the increase of power demand, it cannot satisfy the water demand, which is increasing with higher pace than the power demand.

The case of steam CPDP used in Kuwait is presented in this paper as a reference plant to evaluate the amount of fuel energy consumed to desalt water in MJ/m3, its cost in $/m3. The resulted high fuel cost calls for some modifications in the reference CPDP to lower the energy cost, and to increase its water to power ratio. The modifications include the use of an auxiliary back-pressure steam turbine ABPST supplied with the steam presently extracted to the MSF units. The power output of the ABPST operates MVC or SWRO desalting units; while the ABPST discharged steam operates LT-MEB desalting unit. The desalting fuel energy costs when applying these modifications are also calculated by the exergy analysis and compared with that present situation.

It is also suggested to increase desalted water output by using separate SWRO desalting units operated by the existing power plants of typical η_c = 0.388, or by new combined gas/steam turbines power cycle GT/ST-CC of typical η_c = 0.54 under construction. The SWRO with energy recovery is assumed to consume typical 5.2 kWh/m³ electric energy.     

Catalysis for fine chemicals: towards specificity with polyphasic media

Three examples of the work undertaken at the Institut de Recherches sur la Catalyse for the selective preparation of fine chemicals in polyphasic media are presented and discussed:

1. diastereoselective hydrogenation of 1,2-disubstituted arenes to cyclohexyl derivatives,

2. chemoselective oxidation of anilines, and

3. regioselective alkoxycarbonylation of styrene derivatives to 2-arylpropionic esters.

Factors influencing the selectivity of these reactions are discussed in the light of concepts from molecular chemistry.     

Riyadh''s reverse osmosis water treatment plants - the largest demineralization complex in the world

The water demand in Riyadh has increased very rapidly during recent years owing to the rapid expansion of the city with a population growth of about 50,000 per year. The water from the main source, an aquifer of Minjur sandstone at a depth of 1,200–1,500 m reached, by drilling, has high hardness, sulphate and TDS. The existing water works with raw water cooling, lime-soda softening, sedimentation, filtration and disinfection have been in operation at Malez, Shemessy and Manfouha since 1969. VBB, a member of Swedish Consulting Group (SWECO), is consultant to the Ministry of Agriculture and Water (MAW) regarding the water supply in Riyadh.

In 1973, VBB made an investigatory study on additional water treatment. The aims were to consider the possible need for further improvement of the actual water quality, to point out how such improvements could be achieved and finally, to discuss alternative treatment methods suitable for the purification of water taken from the new well fields.

The purpose of this paper is to give an overview of the technical design and construction of the new water treatment plants in Riyadh, with a total capacity of about 254,000 m³ /d. The treatment of Minjur deep-well water includes not only chemical softening but also demineralization with reverse osmosis (RO) as a final purification stage. The Salbukh plant (50,700 m³/d) should come onstream in autumn 1979.