THE DESTRUCTOR.

Press, Volume LXVIII, Issue 20600, 16 July 1932, Page 16

THE DESTRUCTOR.

DISPOSING OF CITY'S REFUSE.

CHANGES IN THE NATURE OF RUBBISH. A gradual but well-defined change in the nature of the rubbish collected m large cities during recent years has added to the difficulty of the problem of refuse disposal—a problem that has always taxed the ingenuity of municipal engineers. Not only has the quantity of rubbish that it is necessary to dispose of increased with the growth of communities, but it has been found that the material collected by the refuse carts has contained a continually increasing quantity of non-combustible I material. . The change, it appears, dates from the years following the Great War, when electricity and gas began to take the place of coal for home heating and cooking purposes. „ Domestic refuse, in those days, consisted to a great extent of ashes from coal fires and the kitchen range, and such residue contains a great deal of comparatively highly combustible material in the shape of coke, half-burned coal, and other unburned fuel. The Home Incinerator. The home incinerator, however, was an almost universal accompaniment of the gas and electric range, and this proved so thorough a destructor of waste material that its residue was little more than clinker and ashes. Such provided poor fuel for the municipal destructors that dispose of a city's waste material, and whereas previously nothing was necessary for the combustion of the rubbish but the refuse itself, now the use of coal to provide sufficient heat is almost general. The Christchurch City destructor requires a comparatively small amount of "boosting" fuel—about six tons a year. This is used mainly to assist in the destruction of waste fruit and other material that offers strong resistance to heat. Until a few years ago, the destruction of waste fish was a very considerable part of the destructor's functions, but since a use has been found for this in the manufacture of manures, the City has been saved the cost of some 36 tons of coal annually. The City Destructor. The Christchurch destructor is under the control of the Municipal Electricity Department. The carts and . trucks that collect the refuse from various parts of the City deliver it into a hopper at the head of a long ramp in the City Council yards. This hopper transfers the refuse directly into the furnaces of the Meldrum two-unit destructor, which is capable of dealing with about 90 tons of material a day. Ample draught is provided from a "blower" which sends a blast of air through the furnaces, while another fan, at tho foot of the great chimney-stack which is so conspicuous a landmark in Christchurch, provides an additional "induced" draught. The following figures are interesting as revealing the increasing demands made upon the destructor in recent vears:—

Signs of Depression. During the past few years of depression the universal efforts toward economy have been reflected in the character of the refuse collected in the City. Householders no longer use coal to bank up a fire that is not required for a few hours; they have found that vegetable peelings, bones, and other waste serve the purpose admirably. Here again the destructor is deprived of what used to be a valuable item in its combustible diet. Careful housekeepers, too, have realised that they have long neglected a valuable by-pro-duct of their domestic fires —the coke and cinders from the ashes. When separated by means of a sieve or rake, the former proves to be useful and usable fuel.

1930. 1931. 1932. Loads of refuse 18,917 20,922 21,289 Number of fires 7,305 8,229 7,543 Residue, loads of clinker 5,374 6,260 5,763 {Residue, loads of tins 455 563 520 'Tons . of coal burned 42 '> 6 " 6J-