The "Incineration" of Waste Water Containing Large Amounts of Organochlorines.

[NNadir]

Recently I attended a trade mission conference in New York set up for the benefit of the mayor of a large Asian city. (The point of these missions is to fill seats, and that's what I did, fill a seat, although I did get to shake hands with the Mayor, and get his card, even though neither one of us had a clue what the other said, separated by a language barrier.)

The point of the meeting was to hear all about how the Asian city - like every other city on Earth at this time - wants to make a commitment to science and technology as a "way out of this crisis," although no one actually has any intention of "making a commitment to science and technology" that's serious. The scientists and technologists hope the mayors (governors, ministers, Presidents, Premiers, prefects) will give them money, and the mayors (governors, ministers, Presidents, Premiers, prefects) hope the science and tech companies - few of which are actually still run by scientists and technologists - will invents in their (city, state, country, prefect, province.) Neither side actually has real money to give.

But it's fun.

There were lots of people there who were babbling platitudes about so called "green energy" which usually means some kind of scheme for solar and wind power, although neither are actually sustainable, in my view, since they suffer from energy/density issues, reliability problems, and short infrastructure lifetimes and, in fact - although their is much denial on this subject - waste problems. Nevertheless everybody wants these "green industries" so that they can be like San Jose, California, which used to be very proud of its "green" semi-conductor industry, which was to leave large tracts of its ground water in a permanently destroyed state.

The destruction of San Jose's ground water by the way, involved organochlorine compounds, mostly solvents that leaked out of underground tanks.

A lot of money has been spent on cleaning up these tanks and sites, some of which are now "superfund" sites, owing to the fact that the semiconductor business is super and had super funding.

Nevertheless the mayor traveled a great distance from Asia to find "green industries" to invest in his city, even though the city is one of the last in his country to have a pristine environment that is still in need of destruction.

Trade missions involve a lot of sitting around trying to look important, but to be clear, there are some very bright people at these conferences, and I found myself chatting with a fellow who has advised on the building of various kinds of chemical plants around the world.

We got on the subject of what to do with waste plastic, this while drinking out of stupid plastic water bottles even though there were functional water fountains in the hallway, connected directly by pipeline to one of the best tasting city water supplies in the United States, water that is analytically clean and of superb quality and more or less still uncontaminated by plasticizers.

(When in Rome...)

The fellow argued at high temperature reformation of waste plastic in waste to energy protocols were, well, trash, because of corrosion problems connected with chlorine and because of certain other technical and economic points. (I disagreed by the way on most, if not all, of his technical and economic arguments - but I did get something out of the conversation.)

The clean up of organochlorine problems - whether from solvents that leach out of the tanks of "green industries" or from reformation of plastics which may contain chlorine - in water is very difficult, particularly because these kind of reactions tend to generate HCl gas, hydrochloric acid, or even worse, supercritical hydrochloric acid solutions, which are very corrosive.

One approach to cleaning up water containing organochlorines is, in fact, to incinerate it. Although burning water sounds like thermodynamic nonsense - and depending on the circumstances generally is thermodynamic nonsense - oxidizable organic compounds in the water can make the process less thermodynamically odious, and nearly energy neutral, and may be advisable in cases where the point is not really to make energy but to clean the water.

Because of my interest in materials science and high temperature fluids, I came across and read a paper on the subject of incinerating water, which it happens, is out of Asia, China, a place that people assume consists wholly of people who don't give a rat's ass about their environment, although this attitude is glib and disingenuous and, frankly, a little racist.


Here's the abstract of the paper I read: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFK-4DTKHW6-1&_user=10&_coverDate=02%2F01%2F2005&_alid=1072569831&_rdoc=3&_fmt=high&_orig=search&_cdi=5229&_sort=r&_docanchor=&view=c&_ct=3&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=acaccc9c90d67a50554ec359d98bf50f">Chemical Engineering Science 60 (2005) 609 – 616

I found the introduction to the paper interesting, although there is really nothing new and novel about the chemistry involved, which is fairly basic, pun intended, neutralization of hydrochloric acid with lime.

1. Introduction.

The high-temperature incineration of wastewater containing organic chlorine will generate HCl and very little amount of chlorine (Cl₂). Booty et al. (1995) studied the emission of HCl and Cl2 using chlorocarbon in a three-stage incinerator and found that the fraction of HCl emission is much higher than ClX at any combustion condition. Hydrogen chloride can be neutralized by the reaction with calcium-based sorbents, such as solid lime (Ca(OH)₂), limestone (CaCO₃), and calcium oxide (CaO). Recently, many investigations have been undertaken to study the mechanism of the binding reactions and to find the process conditions that affect the HCl-binding capacity of the solid reactants. Ketov et al. (1968) carried out an experiment to investigate the HCl-binding capacity by limestone. They found that, depending on the type of lime, in the temperature range from 723 to 823K there was an optimal temperature, at which a maximum conversion of CaCO₃ to CaCl₂. is obtained. Petrini et al. (1979) studied the HCl binding on porous limestone particles at 623–873K in a laboratory fixed bed reactor. Increasing the particle diameter from 0.2 to 2mm and HCl volume concentration from 1.3% to 4% led to a small conversion of CaCO₃ to CaCl₂.At higher temperature, the molten phase of CaCO₃ and CaCl₂ blocked the pores of the low-porosity solid and then influenced the progress of reaction.

Weinell et al. (1992) reported some data about the conversion of the limestone reacting with HCl (0.1%) in the presence of water vapor (5%) at 353–1273 K. The binding capacity reached the largest in the temperature range of 773–873 K. When the temperature is above 773 K, the binding capacity was limited by the chemical equilibrium between the gas and the solid. Gullett et al. (1992) studied the short time (0.2–1 s) reaction of CaO with HCl at temperature range from 423 to 623K in a fixed bed reactor. The scanning electron microscopy (SEM) evidence indicated that all of the varied particle size cuts were simply agglomerates of submicrometer
grains.

Again, the basic chemistry here should be familiar to any junior or senior high school student in a decent school district, but that certainly is not meant to imply that it isn't useful chemistry. Simple is better than complex in technology, although - the point of the paper and the references cited - simple chemistry can be profitably optimized by looking at it in a sophisticated way.

The authors here did work with a famous organic compound, choral, which is a very old hypnotic/anesthetic agent, now thought to be mildly carcinogenic. They incinerated it in water, to investigate the behavior of HCl during "incineration" of organochlorines. (Strictly put, in the presence of water, choral, trichloroacetaldehyde, is its hydrate and in fact contains no carbon-hydrogen bonds, but only chlorine-carbon bonds and oxygen chlorine bonds, and is therefore not really "organic" in the classic or pop senses of the word, but let's not get too technical.)

The work described in this paper was performed on a bench-scale bubbling fluidized bed shown schematically in Fig. 1, which consists of an electrically heated column with a height of 1100mm and the inside diameter of 32 mm. The bed temperature is automatically controlled by a temperature controller, which allows the bed temperature to vary in the range from 573 to 1273 K. Air is supplied by an air compressor at the feeding rate of 0.1m3 h−1. With the average feeding rate of 60 g h−1, the organic wastewater containing C2H3Cl3O2 is sprayed by a precision pump into a sand dense bed at the height of 240mm above the air distributor.

But my point is that, as is clear from the references and the excerpt, people have been talking about this situation since, um, 1968, more than 40 years ago, and people are still doing "benchtop" chemistry connected with it.

In fact the problem of organochlorine contamination of water supplies is not really getting better and is not "solved" by the industrial "incineration" of waste water. Arguably the problem is getting worse, especially in countries like China, where the West is so willing to dump its wastes so it can feel all warm and fuzzy about being "green."

The next time you feel comforted by some glib benchtop "breakthrough" that someone posts somewhere to help along your denial, I would like to offer that you consider this.

[HamdenRice]

1. Well, you were certainly the wrong person for your company to send!

Kind of like sending a pro-Mugabe guy to a human rights conference.

[NNadir]

2. Well thanks for your kind personal remarks.

I notice that as usual, since you have nothing at all to say about corrosion problems in the reformation of plastic waste - another thing that you know nothing about, can say nothing about and are incapable of caring about - that you have offered a typically insipid response.

You seem to be missing the smiley/rofl.

For the record, I have never hid my ethical and moral contempt for anti-nukes, all of whom I regard as bourgeois brats who wish to offer their self-description as being "green" based on platitudes and wishful thinking and, oh yes, denial about their behavior toward the third world. There are zero anti-nukes who offer any more than that, except when they offer vapid logical fallacies.

Since you know nothing on the subject of carbon reformation, know nothing about Asia's energy infrastructure and planning about it's pathway, we'll just leave it at they, eh, Fundie boy?