Waste water recycling

Remco Engineering - Manufacturer of systems for water treatment, waste water recycling, heavy metal recovery and filtration. Provides some good general information plus vendor specific, http //www.remco.com. ... 

HEIST, J. A. AIChE Symp. Ser. 77 (1984) (209) 259-272. Freeze crystallisation waste water recycling and reuse. 

Wragg, P. Waste water recycling - a case study. J. Soc. Dyers Colour. 1993, 109, 280-282. 

The following drawing shows that about 29% of the solvent are carried into the waste water (which is fed into an internal waste water recycling). The remaining 71% can be found in the used solvent or in the filter cake and were so far disposed of as dangerous waste (Fig. 1). 

Starting with the defined amount of solvent delivered, about 29% of the solvent is carried over into water, arriving at a total of about 104% hazardous waste accumulated. So far - notwithstanding the carry over of solvent - more waste was produced than solvents were introduced because also powder lacquer was found in the waste. This does not include the mass of filter cake of the internal waste water recycling. 

Heist, J.A. (1981) Freeze crystallization waste water recycling and reuse. AIChE Symposium series. No. 209, 77, 259-272. 

Gets cleaning process (GCP) Dry GCP Wet GCP Process detail Waste water treatment Waste water recycling... 

Ellis, Jeffrey I., Waste Water Recycling and Pre-treatment Systems an Alternative to OilAVater Separators, Proceedings of the Annual Meeting of the Air Waste Management Association, 91, 1052-6102 (1998). 

The surviving U.S. plants have embraced all types of waste treatment processes (see Wastes treatment, hazardous waste Wastes, industrial). The most desired poUution prevention processes are those which reduce the total amount of waste discharged. Treatment and disposal are less strongly emphasized options. Zero wastewater discharge faciHties and water recycling processes are becoming more common (55,56). 

After leaving the reactor, the reaction mixture consisting of aniline, water, and excess hydrogen is cooled and condensed prior to the purification steps. First, the excess hydrogen is removed and recycled back to the reactor. The rest of the mixture is sent to the decanter where the water and aniline are separated. The cmde aniline, which contains less than 0.5% of unreacted nitrobenzene and about 5% water, is distilled in the cmde aniline column. The aniline is further dehydrated in the finishing column to yield the purified aniline. Meanwhile, the aqueous layer from the decanter, which contains about 3.5% aniline, is extracted to recover the aniline and clean up the water before it is sent to the waste-water treatment plant. 

AU industrial operations produce some wastewaters which must be returned to the environment. Wastewaters can be classified as (1) domestic wastewaters, (2) process wastewaters, and (3) coohng waste-waters. Domestic wastewaters are produced by plant workers, shower facihties, and cafeterias. Process wastewaters result from spills, leaks, and product washing. Coohng wastewaters are the result of various cooling processes and can be once-pass systems or multiple-recycle cooling systems. Once-pass coohng systems employ large volumes... 

Adhesives and resins are one of the most important raw materials in wood-based panels. Thus, each question concerning the life cycle assessment and the recycling of bonded wood panels does bring into question the adhesive resins used. This includes, for example, the impact of the resin on various environmental aspects such as waste water and effluents, emission of noxious volatile chemicals during production and from the finished boards, or the reuse for energy generation of wood panels. The type of resin has also a crucial influence on feasibility and efficiency for several material recycling processes. 

It has been shown, however, that such catalysts may contain protons, either by design or because of the difficulty in removing all traces of moisture, and these protons have been shown to be superacidic with Hammett acidities up to —18. These protons will also play some role in the catalytic activity of these ionic liquids in practical situations. Ionic liquids in which superacidic protons have deliberately been generated by addition of small amounts of water, HCl or H2SO4 have been used to catalytically crack polyethene under relatively mild conditions. The main products are mixed C3-C5 alkanes, which would be a useful feedstock from waste polyethene recycling. In contrast to other cracking procedures no aromatics or alkenes are produced, although small amounts of polycyclic compounds are obtained. 

Purge from the water recycle stream, to waste treatment, 10 per cent of the flow leaving the methanol recovery column. 

The processed pulp is converted into a paper product via a paper production machine, the most common of which is the Fourdrinier paper machine (see Figure 21.6). In the Fourdrinier system,3 the pulp slurry is deposited on a moving belt (made from polyester forming fabrics) that carries it through the first stages of the process. Water is removed by gravity, vacuum chambers, and vacuum rolls. This waste water is recycled to the slurry deposition step of the process due to its high fiber content. The continuous sheet is then pressed between a series of rollers to remove more water and compress the fibers. 

While all the aforementioned three system configurations can be used for sludge (or fiber) separation, only the recycle flow pressurization system is recommended for water purification or waste-water treatment. 

The results for this scenario were obtained using GAMS 2.5/CPLEX. The overall mathematical formulation entails 385 constraints, 175 continuous variables and 36 binary/discrete variables. Only 4 nodes were explored in the branch and bound algorithm leading to an optimal value of 215 t (fresh- and waste-water) in 0.17 CPU seconds. Figure 4.5 shows the water reuse/recycle network corresponding to fixed outlet concentration and variable water quantity for the literature example. It is worth noting that the quantity of water to processes 1 and 3 has been reduced by 5 and 12.5 t, respectively, from the specified quantity in order to maintain the outlet concentration at the maximum level. The overall water requirement has been reduced by almost 35% from the initial amount of 165 t. 

To avoid this, we have employed hydrophobic resins for concentration and isolation of the products from aqueous media [49]. Organics are retained on the resin and subsequently can be desorbed with solvents such as ethanol, which is useful for green chemistry as it is readily recyclable, renewable and biodegradable. Nonextractive processes offer convenience, can be conducted with high throughput and afford low waste owing to ready disposal of the spent water, recyclability of the resin and the solvent used for desorption. 

Kreysa G (1991) Electrochemical recycling and treatment process for contaminated waste-waters, Abstr KL-5-1, 42nd ISE Meeting, Montreux, Switzerland, Aug 25-30... 

Interest in acid-fixing reactive dyes has remained active because of their environmentally attractive features (section 1.7). The freedom from competing hydrolytic reactions potentially offers exceptionally high fixation, extreme stability of the dye-fibre bonds and complete suitability of the unfixed dyes for recycling. In contrast to conventional reactive dyes, sensitisation problems arising from reaction with skin proteins are not anticipated. Unlike the haloheterocyclic reactive dyes, there is no risk of release of AOX compounds to waste waters. Heavy metals are not involved in the application of acid-fixing reactive dyes, nor are the electrolytes or alkalis that normally contaminate effluents from conventional reactive dyeing. 

Now, from its essential notion, we have the feedback interconnection implies that a portion of the information from a given system returns back into the system. In this chapter, two processes are discussed in context of the feedback interconnection. The former is a typical feedback control systems, and consists in a bioreactor for waste water treatment. The bioreactor is controlled by robust asymptotic approach [33], [34]. The first study case in this chapter is focused in the bioreactor temperature. A heat exchanger is interconnected with the bioreactor in order to lead temperature into the digester around a constant value for avoiding stress in bacteria. The latter process is a fluid mechanics one, and has feedforward control structure. The process was constructed to study kinetics and dynamics of the gas-liquid flow in vertical column. In this second system, the interconnection is related to recycling liquid flow. The experiment comprises several superficial gas velocity. Thus, the control acting on the gas-liquid column can be seen as an open-loop system where the control variable is the velocity of the gas entering into the column. There is no measurements of the gas velocity to compute a fluid dynamics... 

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