Ways of improving the integrity of wastewater network

Summary

The analysis of the main wastewater network failures is given. The data from foreign literature on blockage frequency depending on the pipe diameter is presented; for the classification of pipes by blockage risk level an index, i. e. generalized risk factor is suggested. The index stating the annual number of blockages per 1 km of a sewer of a certain diameter is more acceptable. Periodic maintenance, running or capital repair is a necessary requirement of the operation of any facility. Draining the pipe section under repair is a crucial stage from the point of view of the network integrity. It is suggested instead of one big sewer to lay two parallel sewers with total throughput capacity equal to that of the replaced one. The use of reinforced concrete pipes made of cement fondu characterized by the high corrosion resistance, long lifetime and abrasion resistance is considered. Savings from operation of reinforced concrete sewers made of cement fondu can compensate for its high cost. Polyvinylchloride is a perspective material for sewer production. The attention is drawn to the need of improving standards and regulatory documents related to the sewer maintenance.

Key words

reliability , pipeline , sewerage network , polyvinylchloride , generalized risk factor

Water stand posts: operation experience and advanced technical solutions

Summary

At present about 2.5 thousand water stand posts (mainly KV-4) are operating in the water distribution network of SUE «Vodokanal of St. Petersburg». Their maintenance is complicated by freezing in winter and uncontrolled water consumption. To improve the reliability of water stand posts Okkervil model was designed. A ball valve is used as a shutoff valve. Substituting steel pipe with a plastic one provided for the substantial reduction of the risk of water freezing over the inner surface of the feeding pipe. Improving the design provided for eliminating ejector moveability. The new design lacks sealing rubber rings; the stand post lever force at turning on is reduced. The new fixed ejector has a double seal at the connection to the stand post body. Okkervil water stand posts were tested during two years in the water distribution network of the Primorsk district of St. Petersburg, and starting from December 2012 they have been successfully operating in five cities of the North-Western region of Russia. The advance design of stand posts provides for the reliable operation of municipal and community water networks supplying the residents of houses that lack service pipes.

Key words

water supply network , stop valves , water stand post , ejector , ball valve

Scientific research in the field of drinking water treatment

Summary

From the bibliometric analysis the basic subject areas of the research in the field of drinking water were determined. The leading research institutions, periodicals and countries in this field are presented. The general information on the articles is supplemented with the data on the major scientometric indices based on the citation account: author’s H-index and impact factor of a journal. The basic topical trends are the state of environment, purification of drinking water from different sources, environmental pollution resulting from human intervention, toxicology. Water Research Journal (Great Britain) takes the leading position in water topics. From the data array under consideration (30 597 articles) 25 000 (around 80%) articles have been written by the authors from one country, 5381 articles are the results of the international cooperation. The authors of the articles are representatives from 168 countries. Among pollutants most often mentioned in the publications are: arsenic (1138 articles; 5.1%), fluorides (411; 1.8%), nitrates (351; 1.6%), lead (297; 1.3%), cadmium (274; 1.2%). For the reviewed period (1992–2011) 143 articles were dedicated to pharmaceuticals (0.64%). Among the treatment methods adsorption, ozonation and chlorination are most often mentioned. It was noted that in 2011 the number of published articles on chlorination was almost equal to that on ozonation; however, later the extent of chlorination research increased significantly. The recent popularity of adsorption can be explained not only by the wide use of the given technology in practice but in a greater degree by unsophisticated equipment, low costs of experiments and a great variety of adsorbents, including adsorbents produced from cheap agricultural and industrial wastes.

Key words

chlorination , ozonization , adsorption , array of articles , H-index , impact-factor