Vízügyi Közlemények, 1935 (17. évfolyam)

Kivonatok, mellékletek - Kivonat az 1. számhoz

22 „В", is dry brown clay ; and that from 8 metres, marked ,,C", is wet yellow clay. The sedimentation of the samples A

v B

v С

1 was made with a solution of waterglass (sodium silicate). The samples A

2, B

2, C

2 were sedimentated with groundwater taken out of the bore-hole, and in this way the process actually taking place in nature was reproduced in the laboratory. As is shown in figure 6, the samples A

v B

v C

1 contain 22--25 per cent of colloidal particles (0-002 mm), whereas in the samples A

2, B

2, C

2 .treated with salty ground-water the content of colloidal and silty particles (0-01 mm) is under 3 per cent. It is evident that the clay loses its imperviousness by the action of the salty ground-water. As yet all the efforts of engineers have failed in putting a complete stop to landslips. This can be done by de watering the soaked clay layers by means of stone underdrains, leading away surface waters, and diminishing the steepness of slopes. VI. REMOVAL OF IRON AND MANGANESE AT TEE WATERWORKS PLANT OF BUDAPEST. By D. MOLNÁR. It has become necessary to remove iron and manganese from the drinking water produced by the waterworks plant at Káposztásmegyer for the city of Budapest. This is because that part of the Danube river along which the intake-wells are located, has rapidly been silted-up since the construction of a spur-dike at Megyer. The area where deposits has been formed in the river bed is shown in figure 1. Figure 2 represents a section of the river taken through the silted-up bed between two wells, the one in the left bank, and the other on the opposite side in the island of the Danube. Owing to chemical reactions taking place in the silty water-bearing stratum, the water has taken up a certain quantity of iron and manganese. In order to study this process,' test borings have been made near the wells in the bank and the island, and in the river bed. Samples taken from the test borings and from different soil tratums have been examined. The result of these analyses are shown in figure 2 and table I. The examinations showed that the samples of water taken from test borings made in the island towards the river-branch, as well as from those made in the landward direction, were good in quality, and the composition of the soil was unexceptionable, whereas the water of test borings towards the silted-up river bed contained iron and mangenese, and the soil was contaminated. Experiments carried out to find the proper method of water purification showed chlorination to be the best way of removing iron and mangenese. On the basis of experience gained during one year and a half with a small experimental plant, the final arrangement with an average rate of 15.000 cubic metres per day has been designed ; but the rate may be augmented to 20.000 cubic metres by dosing a due quantity of chlorine. The installation consists of 10 filter tanks of two chambers on the Dabeg system (modified Bollmann system), 6-4 m high and 2-5 m in diameter. The filter material is quartz sand of 1-5 mm in size. The upper chamber of the filter tanks