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“ADVANCED DEVELOPMENT OF A SHIP INSTALLATION FOR PURIFICATION OF WATER FROM POLLUTION WITH MOTOR OILS AND OTHER PETROLEUM DERIVATIVES USING ELECTRICAL CONTROLLED FILTRATION”

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“ADVANCED DEVELOPMENT OF A SHIP INSTALLATION FOR PURIFICATION OF WATER FROM POLLUTION WITH MOTOR OILS AND OTHER PETROLEUM DERIVATIVES USING ELECTRICAL CONTROLLED FILTRATION”
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The digest of the report of  Dr. V.Andreyev  for the International Conference “Cities with Perspective-Sustainable Urban Development in the Heart of Europe” (Berlin, 10-12 Sept.1998) led by senator Peter Strieder and reports for the Conferences in Finland
(April 1997, August 1998)

     Water is one of vitally important substances of nature which, without recognizing the state borders, circulates freely in the earth and near-earth space and is able to unite people  in creation of generally accepted values. But water may separate as well the neighboring regions if somebody of neighbors deals ecologically erroneously with water resources. The slightest distinction from water standard composition propagates very fast over the neighboring regions and creates problems for people, which have done nothing wrong to the water.

     It is no accident that at water usage in all countries of the Baltic region, including those ranking among the most developed countries in EC, there arise problems being similar in many aspects. And if powerful centralized water supply plants in big towns may for the time being cope with deterioration of the supplied water quality, then for small farms and individual users not being connected to the centralized water supply networks it is getting more and more difficult to cope with deterioration of situation in ecology. On these grounds it is possible to assert that development of high-effective facilities of new generation for the decentralized water treatment is actual in the same degree both for areas of non-compact habitation of population in the Leningrad region and for many areas in the countries of Scandinavia and of the Baltic region. As to drinking and domestic water used in the north-western region of the Russian Federation, unfortunately it is often becoming less and less safe as regards its sanitary-epidemiological condition, and not only in the rural areas but in towns and settlements as well. According to some data about 90% centralized water supply networks do not provide for the required quality of tap water, and 70% natural reservoirs have already grown unfit for being used as sources for water intake with the purpose of subsequent water treatment by traditional methods.

     All above-mentioned is the result of interaction between a number of factors which are now typical for the Baltic region. On one side the anthropogenic, technogenic load on natural environment (which in many areas of Leningrad and other regions has already reached the limit of its recreation resource) is becoming stronger. On the other side, the rate of construction, repair and modernization of water treatment and sewage works is being more and more behind everyday needs by force of economical situation the ecological and sanitary-hygienic legislation is lagging to a considerable extent behind demands of the times.

     At present, state enterprises of "Vodokanal" system being responsible for the state of water and sewage water treatment in the towns of Russia, have at their disposal only the technologies and equipment slightly differing from those which were used by civilized countries as long as at the very beginning of our century which would come to an end in two years. In the technical arsenal of "Vodokanal" are available the same water and sewage water settling, iron and aluminum salts coagulation, filtration through sandy filters, sorption (more seldom} and, certainly, chlorinating. Biodegradation methods with the use of aeration tanks and biological treatment ponds have wide application at sewage treatment.

     The chlorinating practice which unfortunately, for anti-infectious reasons goes over reasonable, in terms of physiology, limits, should be an object for a special conversation. At "Vodokanal" works they use water hyperchlorinating as panacea for deterioration of water quality in the places of water intake, which takes place because of insufficient equipment with modern machinery and appliances and owing to general strengthening of   epidemiological threat. This results in rise in endocrine system diseases, metabolic disturbances, nervous and heart diseases, disorders of sense receptors and, finally, in an increase in quantity of oncological diseases. Thus preventing infectious diseases chlorine causes other, more difficult to cure (if at all curable) diseases.

     According to data of the Moscow sanitary inspectors, apart from chlorine the following water pollutants are most often to be revealed in drinking water at higher  percentage levels as compared with the data specified in regulatory documents: iron (about 80%), total organic pollution by value of permanganate oxidizability (49%), color (47%), turbidity (40%), phenols (32%), manganese (29%), residual aluminum (15%), synthetic surfactants (SATs) and petroleum products, formaldehyde, caprolactam, cyclohexanol (about 17%).

     As far as quality of drinking water supplied from the municipal centralized water supply systems is almost everywhere considered as rather low both by specialists and population, a broad market functions of individual and collective decentralized facilities of water treatment (in the market segment of industrial goods), as well as of the bottled "ecologically sound" water (in the segment of food products). Nowadays a great number of apparatus and appliances carrying out tap water final treatment with various indices of efficiency are used for so-called "small water treatment". It is fulfilled on the basis of technological principles such as filtration of different types and sorption. Apparatus for electrical oxidation and reduction of harmful substances or for their coagulation, devices for water disinfection by ozonization and ultraviolet irradiation are spread much less.

Abundance of types and subtypes of water treatment devices is not so much evidence of development of the present class of facilities, as of their lack of efficiency, durability and of the user dissatisfaction with real technical data of these devices. We may reveal objectives reasons for such dissatisfaction if we consider the results of tests run on models being available on the market and aimed at solution of really serious problems of water purification. Seriousness of these problems is stipulated by rather bad state (so to say by rather low technological level and decrepitude) of pipelines being in operation at public services, or by difficulties arising at water intake from natural sources. At this point a number of obstacles arises connected with short service life of filters which, moreover, are overgrown with microflora during operation and show their functioning quality dependence on a number of attendant and difficult of calculation factors. Most of filters available on the market are not suitable for systematic regeneration, which increases operating expenses in  connection with the necessity of replacement of all kinds of cartridges. But a price  fixed at systems with the automated regeneration is unjustifiably high.

     As to the bottled ("spring") water or water purified in a special way, then there are a lot of problems in this, connected with unconfirmed or not completely attested production quality. And random inspections of the bottled water quality send alarm signals informing about available violations of products sanitary standards.

     On the basis of the aforesaid it is possible to conclude that prospects of water supply radical improvement could be revealed within the framework of well-known technologies, first of all at the expense of more intensive construction of modern and modernization of available decentralized water treatment works. However it is clear that because of expensiveness of such programs their implementation, and what is more spreading over rural areas and the areas of individual building, in an overwhelming majority of cases will be postponed for an uncertain period.

     But sanitary indices of water consumed in towns, suburbs and rural areas near large industrial objects polluting natural water sources, should be still brought to sanitary regulations. And the sooner it will happen the better it will be for everybody. It is impossible to think without it of real improvement in people’s health and an increase in average length of human life.

     Nowadays economic and engineering solution of the pure-water problem might be, evidently, found only on the road of creation of high-effective, decentralized water treatment systems of various capacity and of their arrangement right in the places of water consumption and waste water discharge (including large housing units, individual buildings and industrial-consumption objects).

     Thus life itself has brought up on the agenda of our work in collaboration with Finnish companies the tackling of serious problem of creation of a new class of high-effective, compact, economical and easy in handling water treatment equipment. Development of such kind of equipment (being mobile in a number of cases) is required as well to solve diverse problems connected with liquidation of the consequences of emergencies at large water treatment works, in sewerage net- works, at industrial plants, on transport, at oil exploration and production fields, in pipelines, under field conditions and in various extraordinary situations.

     Unfortunately the most realistic, at first sight, way of an increase in capacity of individual water purifiers of well-known types was evaluated from the very beginning as having few prospects for the above-mentioned reasons. It is necessary to search for new, more efficient technologies of decentralized water purification, which would enable to combine the advantages of most of well-known water purification methods with the absence of their drawbacks. It proved to be quite a real task. We have managed to develop systematic approaches to creation of a new generation of local water purification means with application of electrosorption technology. The first models of apparatus of electrosorption type named "Cascade" were created on the basis of new technology. These models excellently retain bacteria, viruses and other microorganisms, any kinds of foreign particles, ions of heavy metals and many other deleterious components. Moreover "Cascades" have ability for a complete regeneration  and owing to it do not require periodical replacement of "cartridges", have practically unlimited service life and may purify water from natural sources (rivers, lakes, wells, holes).

     It is necessary to emphasize, that not only drinking and domestic water used by population should be subjected to thorough purification, but also waste water discharged into natural reservoirs by industrial and agricultural plants and by inhabitants of individual houses. This should be done for prevention of further pollution of drinking water sources. In prospect of the border cooperation, from point of view of ecology, a complete prevention of discharge of raw sanitary and industrial sewage into the Baltic Sea water area, at the expense of perfection and wide spread of decentralized water treatment systems, would be especially actual.

     Development of efficient mobile water treatment unit on the basis of electrosorption would be also useful for solution of diverse problems connected with liquidation of the consequences of emergencies at large water treatment works, in sewerage networks, at industrial plants, on transport, in pipelines, under emergency circumstances caused by natural calamities, and in the first place with river floods and inundation. Moreover it would be highly useful to steer a course of creation of unified, in terms of technology, systems, suitable for purification of both drinking water and all kinds of sewage. The electrosorption technology, which is offered as technical base of the border cooperation project, just gives an opportunity of creation of this kind of unified apparatus owing to the fact that it enables to combine the advantages of most of well-known water purification methods with the absence of their drawbacks.

     For an increase in efficiency of water purification processes we offer to apply a principle of filtration of fluids through through the filled-up diaphragms with the use of phenomenon of electrosorption of polluting components. At electrosorption  a considerable increase in sorption ability of neutral materials (used as filtering packing of "electrocolumns") takes place as a result of their polarization with the aid of external electrical field. At removal of the field, sorption ability of the packing goes down to initial level, providing for an opportunity of the filter regeneration which realizes itself with particular efficiency in the suspended layer of the filter.

     Electrosorption apparatus (EA), unlike chemical-sorption plants, excellently retains bacteria, viruses and other microorganisms. Moreover EAs have practically unlimited service life owing to their ability for a complete regeneration.

Unlike filtration systems EAs have higher capacity which does not decrease in the course of time, as it occurs with membrane or fiber filters. Besides EAs are more compact and have higher efficiency of purification from pathogenic microorganisms and their toxins.

EAs advantageously differ from well-known electrochemical systems at the cost of their ability for a complete removal of pollutants from water, and among them of allergens of microbe origin, which are formed in electrosystems in service, at oxidizing destruction of microorganisms. EAs do not need too in preliminary filtration of mechanical impurities or petroleum products which initial water contains.

     A number of well-known water treatment devices release in flowing water bactericidal ions of iodine, bromine or silver being harmful for health at systematic use. EAs are free from this defect in full.

     Filtration and sorption purification plants which are widespread at present, in the course of operation are overgrown with microflora and practically turn into microbiological reactors worsening (poisoning) water more and more, which results in the necessity of its purification. Owing to simple and reliable preventive measures (convenience of washing and "self-disinfection") EAs exclude this phenomenon in full.

     Unlike filtration and sorption devices for drinking water purification, which are available in the market, EAs do not require periodical replacement of any components in the course of operation. Service life of all components of apparatus EA is rated at long operation.

     Owing to opportunity of simple and regular preventive measures, electrosorption apparatuses for water purification are always in proper working order and ready for efficient functioning, whereas in cases with apparatus of other types a user is not able to determine the time of exportation of their service life (apropos rather insignificant under real loads conditions).

     Availability of electrodes and the fact that they fulfil active electrochemical function, provide for carrying out by electrosorption apparatus the water purification from components being undesirable in excess concentration, such as ions of iron, manganese, chlorine, as well as nitrate, nitrite, phosphate ions and a number of other ones, multiple decrease in the indices of oxygen chemical and biological consumption.

     Finally there is one more important merit of electrosorption technology consisting in a complete exclusion of formation of toxic chlororganic compounds at purification of water from microflora, which becomes its decisive advantage as compared with such widespread and far from being harmless way of water disinfection, as chlorinating.

     On the basis of the above-mentioned and consideration of accumulated data on operation of the first production lots, it is possible to conclude that the offered development and wide spreading of electrosorption equipment presents itself not only real but optimal, for today, way for the solution of  problems of bringing the Baltic area into a healthy region from an ecological point of view.