Process Waste Streams Research Articles

Modelling the performance of membrane nanofiltration—recovery of a high-value product from a process waste stream

For traditional separation processes there are widely available process design methodologies for scale-up and optimization. However, there is an increasing need for such a rational approach to membrane separation processes, identifying at an early stage operating limits and process options. Such predictive models will reduce development risk and time, thus promoting the wider use of membrane technology in process industries such as pharmaceutical manufacture. Design methods exist that have been verified experimentally at the laboratory scale for simple aqueous solutions. There is now a need for the application of the existing theoretical and experimental methods to separations of real industrial interest. In this paper, we demonstrate this philosophy by describing the rationale for modelling the performance of membrane nanofiltration (NF) used in the recovery of sodium cefuroxime, an industrially important cephalosporin antibiotic having activity against most gram-positive cocci. Sodium cefuroxime is produced in a multi-stage biotransformation process with final purification achieved by low-temperature crystallization with excess quantities of sodium lactate. The efficiency of the crystallization process is not 100% and cefuroxime is lost in the waste stream from the crystallization units. Traditionally, this waste stream has been sent for industrial disposal as the concentrations of sodium cefuroxime are too low for normal separation processes to recover. A systematic study of three commercially available membranes indicated that the Desal-5-DK membrane was most suitable for the recovery process. Excellent agreement between the experimental findings and model predictions was observed for batch NF and a membrane charge isotherm was developed for use in process modelling. The full-scale recovery process was modelled theoretically and NF proved more than adequate for the separation required. An estimate of the industrial scale process operating constraints was made and the NF process was considered as a favourable modification to existing plants.

A decomposition approach for an equipment selection and multiple product routing problem incorporating environmental factors

We address a medium- to long-term planning problem concerned with choosing manufacturing and waste mitigation equipment, and routing products, while accounting for environmental effects such as process waste streams and energy consumption. We formulate the problem as a mixed-integer program with an embedded multi-commodity network flow structure. A distinguishing feature of our model is that we allow each machine to be operated in different modes that may affect environmental impacts and costs. Because of this feature, we need a more general type of bundle constraint to model resource capacities. We also require constraints that apply across the network to limit waste generation and energy usage. In network terminology, this is equivalent to allowing bundle constraints to span fairly arbitrary sets of arcs. We develop a new procedure based on Benders' decomposition and column generation to solve the problem. We also present computational experience with this procedure and related insights.

Eutectic Freeze Crystallization with an Aqueous KNO3−HNO3 Solution in a 100-L Cooled-Disk Column Crystallizer

Eutectic freeze crystallization is a novel technique for processing waste and process streams of aqueous electrolyte solutions, separating them into pure water and pure solid salt. A dedicated apparatus, a 100-L cooled-disk column crystallizer, has been developed and tested, combining crystallization and solid/solid separation of ice and salt. Experiments have been performed with a ternary system of aqueous KNO3−HNO3. Heat-transfer rates were achieved in the range of 1300−4600 W·m-2·K-1, which are related to the square root of the scraping rate. The ice product slurry contained 0.15 wt % salt. The ice impurity content after three washing cycles was as low as 15 ppm K+. Well-faceted KNO3 crystals are produced with high purity.

PROPERTIES OF DIFFERENT FISH PROCESSING BY-PRODUCTS FROM POLLOCK, COD AND SALMON

Individual fish processing waste stream components can be used to make feed ingredients or other products. Waste stream components obtained from commercial fish processing plants included heads, viscera, frames, and skins from Alaska pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus); and heads, and viscera from pink salmon (Oncorhynchus gorbuscha). The protein content of heads from all three species ranged from 13.9 to 16.4%; and the fat content ranged from 0.9 to 10.9%. Viscera protein content ranged from 13.0 to 15.3%, and the fat content from 2.0 to 19.1%. After heating to 85C the percent soluble protein in salmon heads was different (P < 0.05) from pollock or cod heads. Percent soluble protein of pollock and cod skin increased 8fold (P<0.05) after the 85C heat treatment. Connective tissue content was calculated from chemical determination of hydroxyproline content, and large differences in percent connective tissue content were found (1% for pollock viscera to 46% for skin). Estimated rat PER values ranged from a low of 2.1 for skin to a high of 3.1 for viscera and fillet samples (P<0.05).

Dioxin sources and industrial emissions control — a review

Dioxin, the collective term for polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans, are generated during various chemical and high temperature processes. They have been shown to be toxic to humans and animals with 2,3,7,8‐tetrachloro‐dibenzo‐p‐dioxin (TCDD) exhibiting the greatest toxicity. Dioxin has been shown to exhibit immunotoxicity, reproductive and developmental toxicity in several animals. Epidemiological studies on groups of humans with prolonged or elevated exposure to dioxin have indicated increased cancer rates above threshold levels of exposure. Conversely, other studies have concluded that dioxin is a net anticarcinogen. There has been much study aimed at quantifying the relative contributions of the identified dioxin sources to the environmental load. Although some data suggests that burning of vegetation produces measurable amounts of dioxin it is rather industrial process waste streams which emit the greatest amounts. Processes implicated include organic chemical synthesis, metal processing, paper pulp bleaching and incineration of organic materials. Dioxin emission reduction strategies for high temperature processes have focussed upon the minimisation of the conditions at which dioxin forms in exhaust streams. Additionally, screening of process materials has been practised as have substitution of process chemicals in the pulp and paper bleaching industry.

Analytical techniques used for monitoring the biodegradation of fluorinated compounds in waste streams from pharmaceutical production

During the assessment of the environmental impact of new pharmaceutical processes the selection and testing of suitable environmental treatment technologies is carried out. A large component of process waste stream treatment practice is aerobic biotreatment in wastewater treatment plants, as it is cost effective and generally more environmentally friendly than harsher chemical/physical treatments. Pharmaceutical syntheses use a range of halogenated compounds (either as reagents, solvents or intermediates) which pose particular challenges to microbial degradation. This is especially so for some fluorinated compounds due to the resilience to enzymatic cleavage of the C–F bond in some cases. The data presented here were obtained from a case study involving the monitoring of the biodegradation of 4-fluorocinnamic acid by means of a range of chromatographic techniques. These methods were used to monitor not only the disappearance of the compound but also the formation of degradation products in order to confirm mineralisation. In addition mass spectrometry was used to elucidate the metabolic pathway.

Dehalogenases applied to industrial-scale biocatalysis.

In the recent past, the development of dehalogenating enzymes for industrial biocatalysis has been limited, but significant advances have been made. Three classes of enzymes have received attention and development: halalkanoic acid dehalogenases (EC 3.8.1.2), hydrogen-halide lyases (EC 4.5.1), and haloalkane dehalogenases (EC 3.8.1). Applications range from the manufacture of chiral intermediates, to recycling of chlorinated byproducts from chemical manufacturing, and selective treatment of process waste streams.

Recovery of polyvinyl alcohol and hot water from the textile wastewater using thermally stable membranes

The recovery of polyvinyl alcohol from the textile process waste streams is presented. Three filtration systems are described that are able to operate at 100°C or above. Two systems are tubular. One uses carbon tubes to support a zirconium oxide membrane and the other uses stainless steel tubes coated with a fused titanium dioxide layer to support a zirconium hydroxide membrane. The third system described is an asymmetric polyvinyl sulfone membrane in a spiral wound configuration. All three systems have been in operation for several years displaying the successful recovery of polyvinyl alcohol. The economics of the recovery process are described. Also presented is the application of automated control to the PVA recovery process and to the recycle of bleaching rinse water to the scouring process.

Recovery of ethyl acetate from process effluents using pervaporation technology

The recovery of ethyl acetate from dilute aqueous process waste streams commonly found in the specialty chemical and pharmaceutical industry has been shown to be effectively performed by membrane pervaporation. A silicone membrane filled with a zeolite material, “silicalite,”; proved extremely effective in yielding high ethyl acetate selectivities under a variety of processing conditions. Permeate ethyl acetate concentrations in excess of 90% were obtained for processing aqueous feed mixtures from 1 to 8% ethyl acetate. The effects of feed concentration, temperature and permeate‐side pressure were examined. Flux increased with increasing feed concentration and temperature, and decreased with increasing permeate‐side pressure.

A review of plutonium(IV) selective ligands

This review compares 40 chelating ligands of differing denticity and basicity for the recovery of Pu from process waste streams. These ligands have been shown to form stable Pu(IV) complexes and to be selective for the Pu(IV) ion. Three plutonophiles identified as potentially cost-effective chelators for waste treatment are the siderophore analogue DFO-HOPO, the novel actinide-chelating diphonix resin and the amide substituted N-macrocycle TCM-12aneN 4. Possible means of isolating Pu on related chelating resins are explored.

An expert system for selecting and sequencing wastewater treatment processes

Wastewater treatment system design involves selecting and sequencing various treatment processes. The design becomes complicated when a large number of processes and various contaminants are considered. In this work, an expert system is developed to find an appropriate treatment process design for a given waste stream. The knowledge base of the system is established with a treatability database to select suitable treatment techniques for specified contaminants and concentration levels. Also, a preliminary fuzzy logic based approach is proposed to express the user's preference of treatment techniques in a linguistic form. The preference is defined on the basis of the treatment efficiency and the cost of a technique. The system is intended to serve as a decision support tool for a designer to determine optimal treatment process sequences for various contaminants at different concentration levels. Finally, the developed system is demonstrated in a case study for a chemical processing waste stream.

An expert system for selecting and sequencing wastewater treatment processes

Wastewater treatment system design involves selecting and sequencing various treatment processes. The design becomes complicated when a large number of processes and various contaminants are considered. In this work, an expert system is developed to find an appropriate treatment process design for a given waste stream. The knowledge base of the system is established with a treatability database to select suitable treatment techniques for specified contaminants and concentration levels. Also, a preliminary fuzzy logic based approach is proposed to express the user's preference of treatment techniques in a linguistic form. The preference is defined on the basis of the treatment efficiency and the cost of a technique. The system is intended to serve as a decision support tool for a designer to determine optimal treatment process sequences for various contaminants at different concentration levels. Finally, the developed system is demonstrated in a case study for a chemical processing waste stream.

The direct combination of HPLC solute focusing with supercritical fluid chromatography and mass spectrometry to enhance sensitivity and improve identification of trace components in polar solvent extracts

AbstractA system for combining normal and reversed phase high‐performance liquid chromatography solute focusing with packed column supercritical fluid chromatography and supercritical fluid chromatography–mass spectrometry has been developed. The technique has been used to identify paracetamol and stanozolol in spiked plasma extracts and its utility for the analysis of a sample from a process waste stream is illustrated.

Supercritical water oxidation: An emerging technology

Environmental constraints continue to force the chemical-petrochemical industry to seek new technologies to process waste streams. The treatment of dilute aqueous streams containing hazardous organic substances has always presented both technical and economic challenges. The MODAR Supercritical Water Oxidation (SCWO) process meets these challenges. The MODAR process for hazardous waste destruction operates at nominal conditions of 600°C and 23 MPa. Under these conditions, organic compounds are completely miscible with supercritical water and with oxygen and nitrogen, and can be rapidly oxidized to CO 2 and H 2O. Inorganic salts, on the other hand, exhibit sharply reduced solubilities, and to a large extent precipitate at reaction conditions. These physical and chemical phenomena lead to an implementation of the MODAR process wherein hazardous wastes are oxidized and inorganic salts are separated in a single reaction vessel. The process is capable of achieving high destruction efficiencies of hazardous organic constituents in excess of 99.99% in a single step. The process precludes the formation of the primary pollutants, NO x and SO 2, and accommodates in situ acid gas neutralization. The basic chemistry and operating parameters of the process were developed by MODAR, Inc. in bench- and pilot-scale operations. More recently, scale-up issues have been identified and addressed in a cooperative engineering development program between ABB Lummus Crest Inc. and MODAR, Inc. The results of this development program have produced a basis for design of commercial plants. This development program and key features and concepts of the design are highlighted in this paper.

Chitosan-poly(acrylic acid): mechanism of complex formation and potential industrial applications.

The food industry is interested in polyelectrolytic coagulants of natural origin for the clarification of food beverages and the recovery of colloidal and dispersed particles from processing waste streams. This paper discusses potential industrial applications of recent findings on polymer complex formation obtained with a chitosan-poly(acrylic acid) model system. Process recommendations could be made on the basis of the ionic strength, pH, and charged group concentration of the fluid to be treated. Ionic strength does not affect the complex formation process. The amount of chitosan in the complex formed is controlled by the solution pH. The mechanism of complex formation indicates that pH measurements could be used to monitor the coagulation process.

Metabolism of glyphosate in Pseudomonas sp. strain LBr.

Metabolism of glyphosate (N-phosphonomethylglycine) by Pseudomonas sp. strain LBr, a bacterium isolated from a glyphosate process waste stream, was examined by a combination of solid-state 13C nuclear magnetic resonance experiments and analysis of the phosphonate composition of the growth medium. Pseudomonas sp. strain LBr was capable of eliminating 20 mM glyphosate from the growth medium, an amount approximately 20-fold greater than that reported for any other microorganism to date. The bacterium degraded high levels of glyphosate, primarily by converting it to aminomethylphosphonate, followed by release into the growth medium. Only a small amount of aminomethylphosphonate (about 0.5 to 0.7 mM), which is needed to supply phosphorus for growth, could be metabolized by the microorganism. Solid-state 13C nuclear magnetic resonance analysis of strain LBr grown on 1 mM [2-13C,15N]glyphosate showed that about 5% of the glyphosate was degraded by a separate pathway involving breakdown of glyphosate to glycine, a pathway first observed in Pseudomonas sp. strain PG2982. Thus, Pseudomonas sp. strain LBr appears to possess two distinct routes for glyphosate detoxification.

Removal of cadmium from metal processing wastewaters by reverse osmosis

Abstract Reverse osmosis has effectively been utilized to remove cadmium from a metal processing waste stream. Experimentation with a thin‐film composite membrane reduced cadmium concentrations from 165 to 0.003 mg/L under optional processing conditions. Concentrations of other metals and overall conductivity were rejected in excess of 98%. Rejection efficiency and production rate were increased by an increase in system operating pressure. Cadmium was effectively concentrated in a batch concentration study while generating high quality water for process reuse. Membrane fouling is a problem if proper in‐line prefiltration is not utilized. Reverse osmosis appears to be an effective alternative to other more traditional treatment methodologies.

Concentrations of rare earth elements in sediments, mussels and fish from a Danish marine environment, Lillebaelt

Results for the content of the rare earth elements (REE), La, Ce, Nd, Sm, Eu, Tb, Yb and Lu in sediments, mussels and fish are presented for an area polluted by REE. The REE are emitted with the process waste water stream from a fertilizer production plant. The method of analysis has been INAA. An attempt to combine the INAA with a simple destruction/preconcentration method is described.

Characterization of selected epa priority pollutant elements in process and potential waste streams of an experimental low-btu gasifier

To aid in assessment of potential environmental consequences of coal gasification, process streams of an experimental, fixed-bed Wellman—Galusha gasifier were analyzed. Selected Environmental Protection Agency priority pollutant elements were analyzed by atomic absorption spectroscopy. These analyses were intended to aid in the evaluation of the effectiveness of product gas clean-up devices and provide data for improved human health risk estimates. We analyzed samples of Venturi scrubber water, tars from the humidifier and tar trap, dust from the cyclone, and raw and cleaned samples of process gas. Lead, chromium, and arsenic in the Venturi scrubber outlet water were present at 100, 40, and 26 times the limit of the primary drinking water standard (0.05 ppm) for these elements. Significantly higher concentrations of sodium and potassium were observed in the smaller particles than in the larger particles collected by a high-temperature high-pressure cascade impactor from the raw process gas. Enrichment of chromium and nickel in process stream particles during passage through the clean-up system may indicate some erosion of the gas producer.

Ultrafiltration and Reverse Osmosis Recovery of Limonene from Citrus Processing Waste Streams

ABSTRACTCommercial ultrafiltration (UF) and reverse osmosis (RO) membranes were used to concentrate the terpene, limonene, present in cold pressed oil centrifuge effluent and molasses evaporator condensate. UF membrane rejections were 78–97% for mixtures with initial limonene concentrations from 0.04–0.6%v/v. RO membrane rejection of limonene ranged from 87–99% for feed streams containing 0.06–0.23% limonene. Initial membrane flux rates for centrifuge effluents were in the range 10–100 kg/m2/hr. Evaporator condensate fluxes were higher, 25–400, while pure water rates ranged from 25 (RO) to 1000 kg/m2/hr (UF). Contact with limonene adversely affected membrane flux rates in decreasing order of severity: polysulfone &gt; cellulose acetate &gt; teflon‐type.