Clay Beads Research Articles

Anaerobic digestion of high-strength acidic whey in a pH-controlled up-flow fixed film loop reactor

A fixed film loop reactor was developed for the stabilization of undiluted sour whey. Porous clay beads were used to immobilize the population. The fermentation system was self-supporting with the aid of a pH-titrator. Within 2 months; the loading increased automatically to its maximum of 14 kg COD (chemical oxygen demand)/m3 per day. Parallel to this, the bacterial film was formed on the surface of the support material. For a pH of 6.7 the steady state was reached at a hydraulic retention time of 5 days equivalent to a loading of 14 kg COD/m3 per day. An amount of 5.6 m3 biogas was produced per m3 digester content and day and the COD-reduction was 95%. The pH-controlled whey addition led to only minor disturbances when overloading or oxygenation occured and a fast recovery of methanogenesis was observed. The economics of anaerobic whey digestion compared with conventional whey utilization is estimated by a simple cost/benefit calculation.

Central Asiatic Gold Mines of the Bronze Age

THE sources from which prehistoric peoples ob tained their minerals and other raw materials of industry afford valuable clues to their intercourse and cultural and economic contacts. A new source of gold in Central Asia is reported in the announce ment of a discovery of prehistoric workings at Kazakhstan by a Russian expedition sent out by the Soviet Government (Soviet Union Year Book Press Service). The mines had been worked by a large number of workmen who used some implements of bronze, but for the most part of stone and the bones of animals. There were no traces of iron. Near the shafts were primitive ore-crushing plants, consisting of stone slabs and hammers. Two skeletons of these bronze age miners were found, who had met their death by a fall of the roof. On one of the skeletons was a necklace of glass and clay beads and in one hand was a bronze chisel and in the other a stone hammer. They were not Mongolian, as was indicated by their skulls. The mines were 0-75 m. wide and 20-25 m. deep. They were connected by underground passages 100-150 m. long. These passages had natural ventilation, and for illumination it is probable that fat in shallow bowls was employed. Some of these bowls have been found. Stone cross pieces were used as props. Polished slabs and triangles of stone have been found which appear to have been used on the steppes of Kazakhstan as sign-posts to guide caravans on their way to the mines. The slabs were orientated and polished on the eastern side. The Soviet Government is sending out another expedition this year to explore the mines further, and to work the ore which was left unextracted by the ancient miners.

‘The Ring of Nestor’: A Glimpse into the Minoan After-World and A Sepulchral Treasure of Gold Signet-Rings and Bead-Seals from Thisbê, Boeotia

The first subject of the present communication is a truly royal treasure of gold rings and of bead-seals in the same metal found in a Mycenaean rock tomb near the site of Thisbê in Boeotia. The find was made in 1915, at a time when war conditions diverted the course of discovery from official channels, and a fortunate chain of circumstances now enables me not only to describe but to exhibit to the Society the whole hoard. Under the circumstances it is impossible without a breach of confidence to give all the details, but, from what I have been able to ascertain, the discovery was made by a peasant in a chamber-tomb excavated in the rock, by the village of Dombrena. Near this spot, about a quarter of an hour N.W. of Kakosi, on the Akropolis height of Thisbê, Mr. W. A. Heurtley, of the British School at Athens, kindly informs me that he was shown, in an olive grove, three chamber-tombs with dromoi. He adds, ‘The old man who showed me had dug one completely and found a dagger and vases and some sherds, all of which he had lost.’ Mr. Heurtley adds, however, that, from a drawing that the old man made of one of the vases, it is clear that it was a stirrup-vase of late type.Other objects that I myself was able either to see or secure, found in the same group of tombs, but not authenticated as coming from the chamber containing the treasure, were bronze spear-heads and a short sword with the flange running round the extremity of the hilt, belonging to a very late Mycenaean type. A bronze razor also occurred of an advanced form and, of still later date presumably, a small perforated double-axe head of iron. There were also found a whole set of perforated glass-paste objects with holes below for the attachment of pendant gold disks which Mr. Wace has now conclusively shown to belong to necklaces. The particular type found, as well as certain paste pendants with reliefs covered with gold foil, belongs to the date of the Dimini jewels, or early L.M. III. b, in Minoan terms. There is no difficulty in ascribing the radiated glazed clay beads (Fig. 1, a) and the bugle bead of kyanos blue paste (Fig. 1, d), as well as the plated faience plaques with groups of palms in relief (Fig. 1, k), to the same epoch.