Waste Incineration Plants: a Hazard for Russia

S.S. Yufit, Doctor of Chemistry

 WATER POLLUTION

Fixation of dioxin particles occurs not solely in the air; a similar process takes place in water. In England, to the north from Birmingham, there was an operating hazardous waste incinerator (run by Coalite Chemical). In 1991, hazardous quantities of dioxins were detected in cows’ milk at three farms; for this reason, sale of milk from those farms was prohibited. Inspection of the region showed that the dioxins were accumulated not only in the soil around the incinerator, but also along the waterway of the Doe Lea River. High concentrations of dioxins were detected as far as at a distance of 1.5 km from the wastewater discharge point (Waste Not, # 187, March 1992).

In the course of our researches of bottom deposits in the Northern Dvina, it was found out that discharges of dioxins leaving pulp-and-paper mills were spreading over tens and even hundreds of kilometers; though, as I have already mentioned, they are poorly soluble in water, there may be a large quantity of them on silt particles.

But where does the water pollution come from? Where is the source of pollution of the waste waters? The first source of pollution is water which is used for the cooling of refuse burnout. Refuse burnout contains a lot of heavy and toxic metals. Non-volatile metals pass into the burnout; volatile metals pass both into the burnout and into effluent gases; mercury becomes part of the effluent gases (Table 1).

Table 1: Typical composition of effluent gases emitted by an incinerator

 

Other sources of pollution are the scrubbers, which are used for the capturing of acid gases after the cooling of gases discharged from the incinerator, and water for the washing-out of filter residues. Such water is rather toxic and requires special purification. It was such water that polluted the Doe Lea River in England, because the incinerator in question was used solely for the disposal of liquid toxic waste.

Table 2 shows the efficiency of acid scrubbers. It is apparent that nitrogen oxides and carbon monoxide are not captured by such treatment facilities at all.

 

The average amount of resulting wastewater per 1 ton of burned waste is 2.5 m³. Such water is heavily polluted with salts and toxic metals (Table 2).  It is either highly alkaline or strongly acidic. Both variants are equally bad; in either case, special water treatment is required. At incinerators, which are not fitted with heat removal provisions, water is injected into hot gases in order to generate energy; the water evaporates completely and gets, together with the gases, to clean-up filters, and further to wastewater collection system.

There is another hazard which arises in connection with polluted water which has been used for the washing-out of refuse burnout at garbage dumps. It was found out that such water contained not only a lot of toxic metals, but also hazardous quantities of polynuclear aromatic hydrocarbons (PAH).

TYPICAL OMMISSIONS OF AUTHORS OF INCINERATOR PLANT PROJECT IN RUSSIA

Environmental Impact Assessment (EIA) Section

In many projects, this section is prepared with considerable negligence; as a result, conflicts with public occur. Environmental impact assessment is substituted for by (and often confined to) an analysis of composition and figures of emissions and discharges:

1) Alternative projects are not considered. This essential requirements is ignored entirely either under the pretext of alleged superb efficiency of the given project (which makes consideration of any other projects unnecessary) or by a reference to an urgent necessity of solving the problem of waste elimination. Finally, when alternative projects are considered, evaluation of economic parameters is omitted. The unwillingness to carry out a comparative economic analysis is understandable, since waste incineration is more expensive than its burial, and authors of such projects have to present strong reasons to justify the increase in cost of waste collection.

A typical example: Cost of construction of an incinerator plant in the suburbs of Moscow was estimated at 80 billion rubles, whereas removal of waste cost the city 2 billion rubles per year. At the meeting of the community, it was pointed out, as an argument against the construction of the plant, that the sum of 80 billion rubles would be sufficient for 40 years in terms of waste removal. As a result, the construction of the plant was prohibited.

2)    Incorrect sizing of sanitary zones. Any waste incineration plant is a hazardous production facility (Hazard category not lower than 2); therefore, any attempts to substantiate shrinkage of the sanitary zone are inadmissible. A common argument for reducing the size of the sanitary zone is the alleged “unique purity” of emissions of the given incinerator, which is said to have “no equivalents abroad”.

A typical example: Authors of a certain project suggested a sanitary zone of 180 m; otherwise, a military housing area would be covered by the sanitary zone. The authors of the project insisted that: 1) inhabitants of the military housing area were not considered residents of the city in question; 2) emissions from the incinerator plant were so pure that they could harm neither the people nor the environment. Result: the Sanitary and Epidemiological Inspection (SanEpidNadzor) withheld the approval for construction of the plant.

3)    Evaluation of the impact of harmful facilities on the environment (forests, water bodies, and the animal world) is missing. This omission is especially dangerous in cases when construction of an incinerator plant is planned near forests ranked among Group 1, at the boundaries of national reserves or near rivers or lakes.

A typical example: Because of massive protests on the part of the community, the land allotment for construction of modern waste burial facilities in the Vladimir Region has not been approved by the authorities to date. The community is protesting against the cutting of a portion of a water-conservation forest. At the same time, incinerator plants are much more hazardous than modern waste burial facilities (landfills).

4) Remote effects of operation of incinerator plants are not considered. This remark is made with respect to substantiations of safety of a given incinerator plants on the basis of calculated low levels of pollution (in fractions of maximum allowable concentration). Yet, the criterion of maximum allowable concentration is not applicable for analysis of remote effects of discharges/emissions containing heavy metals, lead, cadmium, and dioxins, which are highly stable; such substances become accumulated in the environment, and, as the incinerator operates, their level inevitably increases.

The criterion of maximum allowable concentration is totally unacceptable for dioxins. We can state this based on the established fact that there is no safe dose of dioxins no matter how low it might be (Refer to US ÅÐÀ Health Assess­ment Document for 2,3,7,8-Tetrchlorodibenzo-p-Dioxin (TCDD) and Related Compounds. EPA/600/BP-92/OOlc, August 1994). The acceptable daily dose according to Russian standards is 10 pg per 1 kilogram of weight per day; American standards specify a dose which is a hundred times lower. These standard values are established out of sheer inability to control the situation; the already existing levels of dioxin pollution in the Western countries are so high that it is far beyond the mentioned values. Incinerator plants are main sources of dioxin pollution. In Russia, such facilities are still a rare thing; consequently, the background pollution level is lower than that in the West.

A typical example: Long-term operation of a waste incinerator in Rotterdam (the Netherlands) had resulted in such pollution of cows’ milk within a radius of up to 30 miles from the incinerator location that sale and consumption of such milk was prohibited. Because of high content of dioxins in effluent gases at an incinerator in Zaanstadt, pollution of the adjacent territory exceeded the average pollution in the Netherlands by 50 to 100 times. Result: The incinerator in Zaanstadt (together with 3 other plants) was closed; other incinerator plants in the Netherlands spent millions of dollars for modernization of gas purification systems.

In Poland, two incinerator plants, which had been emitting dioxins at a level of 15 to 23 ng TEQ/m³, were shut down. Similar examples are available in England, Canada, and other countries.

5) Extreme stability of dioxins should be taken into account. No matter how low the emissions of dioxins are, they will remain in the environment for decades. That is why there is always a polluted area around even the best incinerators which fully comply with Directives of the European Council. Such an area is usually well-defined within a radius of up to 1.5 km from the incinerator chimney; in case of long-term operation of the plant, this area covers up to 30 km. Large aerosol particles fall out within the close-in area; small particles may spread over tens of kilometers.

In Holland, specialists conducted a direct measurement of dioxin content in the air at a distance of 1 and 24 kilometers from three incinerator plants. At a distance of 24 km from the source of dioxin emissions, the dioxin concentration was less than 3 times lower than at a distance of 1 km (0.24 pg/m³ versus 0.6 pg/m³) (Refer to Van Jaarsveld J.A. Onderlinden D. RIVM nr. 738473007, juni 1989). All researches conducted in various countries showed a distinct deterioration of health of people (especially children) in areas around incinerator plants.

6) Dioxins remain in the environment for decades. In South Vietnam, at locations of dioxin pollutions, dioxins are still present in nearly the same quantities as 25 years ago, when these areas were subjected to the action of agent orange.  The dioxins still affect the animal world, the vegetable life, and health of people. This proves the fact that there are no such technical solutions for incineration of unsorted waste that would allow avoiding irreparable damage to nature and human health.

WASTE FEEDING SYSTEMS

Waste should be weighed and sorted (at least, partially). Currently, especially in big cities, waste tends to contain large quantities of aluminum unless it is sorted out. When a large amount of aluminum gets into the combustion zone, a thermal explosion may occur.

Reserve waste storage bin, which is required for smooth operation of an incinerator, is a high-risk object. Along with violation of sanitary and hygienic requirements to labor conditions, storage of waste for many days and even weeks entails generation of methane, which is explosive. If such a bin is indeed required, its design should include the following provisions:

a)     Discharge via the bottom portion of the bin (in order to avoid long-term storage of waste). If authors of a project fail to find a proper technical solution for bottom discharge, provisions should be made for complete cleaning of the bin at least once a week.

b)    Powerful forced ventilation of waste (in order to avoid explosive concentrations of methane).

c)    Air from the bin should come to the incineration furnace, but not to the chimney.

A typical example: In one of the projects, it was suggested that waste should be fed to the furnace using a clamshell crane; this meant loading over 100 kg of wet fuel material into the furnace at a time. Specialists remarked that such an approach was likely to result in rough burning and unsteady operation of all furnace systems. The authors of the project declared that they would not have any roughness of operation, and that the mentioned approach was their “know-how”. Result: The specialists’ remark was included in the “negative opinion”.

INCINERATION FURNACE

According to Directives of the European Council, geometry of the hot zone of an incinerator should ensure the staying of gases in a zone with a temperature of not less than 850°Ñ for a time period not shorter than 2 seconds (“The rule of two seconds”) at oxygen concentration of not lower than 6%. It should be noted that the requirement is rather severe, and it is not easy to comply with. Ensuring the high concentration of oxygen in the burning area is of especial difficulty.

Authors of projects tend to demonstrate two very grave fallacies:

1) Complying with the “rule of two seconds” allows complete destruction of dioxins; in fact, this is far from being true. Meeting the “rule of two seconds” means that the concentration of dioxins in effluent gases will be acceptable to allow their purification to the specified value of 0.1 ng/m³ (with 11% of oxygen in the gases). It is assumed, also, that the efficiency of purification will be not lower than so-called “six nines”, i.e. 99.9999 96;

2) At a high temperature “everything will burn away”. Falsity of such an allegiance is obvious. Besides, authors of projects omit another property of dioxins, i.e. a capability for new synthesis in the cold zone. Unawareness of this fact makes the authors to include additional high-temperature zones (so-called afterburning zones) in their projects. Such zones, though, are utterly useless in terms of reduction of dioxin concentration in effluent gases.

Note. The issue of efficiency of the afterburning high-temperature zones has been extensively discussed in literature. Majority of the available data demonstrate inefficiency of this method in terms of reduction of concentration of incomplete combustion products. Commoner (Commoner Â. at al.Waste Management and Research 5:327-346, 1987) and Hagenmaier (Hagenmaier H. at al. ibid. 5:239-250, 1987) report that inspections of incineration furnaces have showed that dioxins are generated in the process of burning, and are further synthesized in the cooling zone; therefore, a higher burning temperature does not ensure destruction of dioxins.

Back in 1987, Trenholm and Thurnau showed that emissions of 15 toxic substances (incomplete combustion products) from furnaces of different types did not become purer after increasing the temperature from 700 to 1500°Ñ, increasing the time of gases’ staying in the furnace from 2 to 6 seconds, and increasing oxygen concentration from 2 to 15 % (Trenholm A. and Thurnau R. Proceedings of the Thirteen Annual Rasearch Simposium. Cincinnati, OH: U.S. EPA Hazardous Waste Engineering Research Laboratory, EPA/600/9-87/015, July 1987). And, finally, high temperatures lead to an increase in volatility of components, which results in increased emissions of hazardous metals.

Thus, the method of reducing the concentration of toxic substances by means of afterburning is not well-grounded, and fails to contribute to reduction of total emissions of incomplete combustion products and heavy metals in any way.

PURIFICATION OF EFFLUENT GASES

1. Quality of gas purification. In evaluation of quality of gas purification, we should follow the Standards of the European Community accepted in Russia.

A typical example: In one of the projects (an equivalent of incinerator plants located in Pyatigorsk and Crimea) the following values (Table 3) were included in design.

 

It should be noted that Table 3 does not provide any data on dioxin emissions, the issue of which is a “corner stone” for evaluation of efficiency of any incinerator. According to European standards, dioxin content in effluent gases (with 11% oxygen content under normal conditions) may not exceed 0.1 ng/m³ in toxic equivalents I-TEQ. It is obvious that the emissions of toxic substances as presented in Table 3 are entirely unacceptable. As a result, the project was rejected.

2.         Structure of effluent treatment facilities. The primary mistake of projectors of treatment facilities consists in poor awareness of factors influencing the reduction of dioxin emissions. The generated dioxins are mostly adsorbed by flue cinder particles; therefore, reduction of dust content contributes to reduction of pollution of combustion gases with dioxins. However, after the passing of gases through hot electrostatic filters, the content of dust will be reduced, whereas concentration of dioxins may become even higher. The only equipment which really ensures a reduction of dioxin content in gases is the charcoal filters, where dioxins become inevitably fixed; besides, there are special catalytic afterburners combined with NO_x afterburning function. It is the difficulties in the capturing of dioxins that entail the expensiveness of effluent gases treatment facilities at modern incinerator plants.

A typical example: The treatment facilities of a projected incinerator plant included a charcoal filter, which was expected to operate in “special situations” only. However, other filters failed to ensure a reduction of dioxin content in effluent gases. Result: The project was revised in terms of treatment facilities, which resulted in higher cost of the project and in an increase of the amount of hazardous waste subject to burying.

3. Quenching of effluent gases. The assumption that an abrupt chilling (“quenching”) of effluent gases will reduce the amount of dioxins is a common fallacy. True quenching implies a reduction of temperature by many hundreds of degrees within fractions of a second, in order to “freeze” the state of thermodynamical equilibrium achieved at a high temperature. It is hardly achievable under actual incinerator conditions. Even if the authors of such projects succeeded in freezing the hot gas mixture, they would not achieve any reduction in dioxin concentration, because “new” dioxins would be generated not in the vapors, but on the surface of flue cinder particles.

A typical “quenching” pattern is as follows: Combustion gases at a temperature of over 850°Ñ come either to the water spray chamber or to a waste-heat boiler, where they are chilled down to approximately 320ºÑ. In Chemosphere magazine (1987, 16, # 8-9, ð. 336-343), authors specify the most favorable conditions for formation of dioxins, i.e. the range of 300 to 400°Ñ. These are exactly the same temperature conditions under which the gases are chilled in the waste-heat boiler prior to treatment. It should be remembered generation of “secondary” dioxins may start at temperatures lower than 700°Ñ (the temperature at which their decomposition begins), and, according to data provided by the US Environmental Protection Agency (US ÅÐÀ Background Doc­ument for The Development of PIC Reg­ulations From Hazardous Waste Incin­erators. US EPA Office of Solid Waste, October 1989), the lower experimentally-reached threshold for such generation was in the range of 250 to 350°Ñ; thus, it is obvious that the waste-heat boiler in the above-described “quenching” pattern is an ideal reactor for generation of “secondary” dioxins. In the event that the effluent gases have low oxygen content (and the European standards require at least 6 % of O₂ in the gases during combustion) the efficiency of such a reactor for production of “secondary” dioxins will be even better. It should be also taken into account that “quenching” is possible only at those incinerator plants which are not intended for production of energy.

4. Main equipment for purification of effluent gases at modern incinerator plants (e.g. in Alkmaar, the Netherlands:

♦    Electrostatic filter for dust elimination

♦    Water sprayer (evaporation of polluted water) for the cooling of gases and partial removal of HCl

♦    Another electrostatic filter for additional capturing of salts (formed at the previous stages) and smaller dust particles

♦    Acid gas scrubber (Stage 1) for removal of ÍÑ1

♦    Alkali-liquor scrubber (Stage 2) for removal of gaseous ÍÑ1, HF, S0₂

♦    Post-scrubber wastewater treatment (neutralization, flocculation, and deposition). The purified water comes to the sprayer.

♦    Heat exchanger

♦    Reactor with additional introduction of active carbon (for primary removal of dioxins)

♦    Dust filters for removal of fine dust particles

♦    Gas heating prior to calalytic afterburning of  nitrogen oxides

♦    NO_x suppression reactor (with NH₃). Such a reactor is nowadays combined with the calalytic afterburning of dioxins.

Thus, the system comprises three anti-dust filters, two sprayed scrubbers, an activated charcoal filter, and a nitrogen oxides afterburning system.

ECOLOGY-ORIENTED APPROACH

The matter of principle is the ecological evaluation of incineration of non-sorted waste, and, accordingly, construction of incinerator plants for this purpose.

Ecology is not a sum of measures for environmental protection. Moreover, environmental protection is only one of the spheres of applied ecology. In the context of the fundamental principle of ecology, which is the preservation of the home where we are living, incineration of a non-sorted stream of waste is an anti-ecological act. We are irretrievably destroying the substances that were taken from nature; this is inadmissible in the context of a global approach to the problem.

Besides, construction of such incinerator plants is extremely harmful in humane and social terms, since operation of an incinerator requires a stable stream of solid household waste both in quantity and in composition; this is the basic principle of operation of any production facilities.

Thus, such incinerator plants (and their owners) contribute to “preservation” of municipal situation with respect to waste, and are likely to oppose any changes in methods of household waste disposal.

TOXICITY OF REFUSE BURNOUT AND FLUE CINDER

Due to experimental nature of incinerator plant projects, their authors are unable to determine the sanitary and hygienic properties of refuse burnout and flue cinder. Refuse burnout and flue cinder which are produced by ordinary incinerators are highly toxic; project authors must check their toxicity by studying the process of combustion of actual solid household waste. In some projects, it is suggested that the burnout be used for production of cement items or industrial glass. There are no questions with respect to use of burnout for production of glass; however, with cement products, the matter is more difficult. Currently we have controversial data with respect to such a way of recycling; the question is that any changes in the ðÍ value of the environment may bring about washing-out of toxic heavy metals. Flue cinder is extremely toxic; any attempts to make use of it are connected with high hazard. At modern incinerator plants, flue cinder is usually buried in special landfills. At an “exemplary” plant in Vienna, the resultant cement blocks are buried in old salt mines.

EMERGENCY SITUATIONS; SHUTDOWN OF THE PLANT

Usually, authors deem their projects rather reliable, and do not consider emergencies, including the following:

♦    Explosions in the hot zone

♦    Burn-through of the afterburning zone walls or the furnace bottom

♦    Emergency stoppage of the incineration process in the event of a failure at the air ducts or due to interruptions in the waste feed or gas supply.

According to European standards, a furnace should shut down automatically if the temperature in the burning zone drops below 850°Ñ. An emergency shutdown results in an abrupt increase in dioxin emissions. A similar increase in emissions occurs in the beginning of the furnace operation; therefore, the European standards allow beginning of the incineration process only after the furnace has been warmed up to 850°Ñ.

PREPARATION OF SOLID HOUSEHOLD WASTE FOR INCINERATION

The issue of preparation of solid household waste for incineration is in fact the most important one for evaluation of the suggested technology. If we assume that the waste has been properly sorted out, the waste coming to the incineration plant contains approximately 4% of plastic materials, which is quite enough for an efficient generation of dioxins. The only result of removal of paper and cardboard from the waste is the worsening of thermal performance of fuel, whereas value of the dirty waste paper is doubtful. And, we have already discussed the food products. Thus, the composition of waste coming to incineration plants from Moscow changes but negligibly after manual separation (except for removal of glass and non-ferrous metals). For fluctuations in the waste composition, the value of 20% is common. I will repeat again: A small decrease in the amount of plastic materials cannot have any significant impact on dioxin emissions. Some authors (Í. Rigo, Dioxin and chlorine: new evidence of no material relationship in a commercial scale system. Organohal-ogen Compounds, 1998, 36, 261) state that there is no connection at all between presence of plastic materials (those containing chlorine) and dioxin emissions; however, there are different opinions as well (P. Costner. Correlation of chlorine input and PCDD/PCDF emis­sions at a full-scale hazardous waste in­cinerator. Organohalogen Compounds 1998, 36,147). In spite of the scholarly discussions, there is only one conclusion: A decrease in the concentration of plastic materials from 15 to 9 thousand ton per year does not entail any changes in the intensity of dioxin emissions. Thus, the sorting of waste (the “greenest” operation) is, in fact, inessential for changing the toxic characteristics of the stream of solid household waste, whereas the economic expediency is not discussed in the project. It is only natural, since, unfortunately, the market of secondary raw materials practically does not exist in Russia.

The fundamental difference of Moscow (Russian) fuel from the European one lies in the fact that the European waste is sorted at the collection stage, and not at the combustion stage. In some countries (e.g. in Sweden), more than 70% materials, which are fit for recycling, are planned for further use. Let’s give an example of Vienna (Austria). 1.8 million of residents “produce” 835 thousand ton of solid household waste (1998); 40% of the residents participate in the sorting-out of waste at the collection stage. They sort out 30% of the total amount of solid household waste (250 thousand ton per year). 9.5% of waste is used for composting; 11.5% of waste is buried at special landfills (not garbage dumps!); the rest is burned at an incinerator plant in Vienna (but prior to burning, the waste is separated).