Deep shaft plant

Case III Deep Shaft Plant at Ohtsu Paper Company... 

The deep shaft plant at Ohtsu Paper Co. came on line in 1980. It treats the wastewater generated by a cardboard recycling facility located within 18.3 m (60 ft) of a residential area inside the city of Ohtsu. The plant discharges treated wastewater to a beautiful recreational body of water named Lake Biwa. 

Flow to the deep shaft biological wastewater treatment plant is screened and goes through a DAF unit for fiber removal prior to entry into the deep shaft. The Ohtsu plant consists of one shaft 2.79 m (110 in.) in diameter by 100 m (330 ft) deep. The shaft design incorporates one downcomer and one riser where the downcomer is located concentrically within the shaft with the resultant annular volume serving as the riser. Mixed liquor in the shaft is maintained at approximately 5000 mg/L and the hydraulic detention time in the shaft is 1 h. Mixed liquor enters the head tank at the top of the shaft where gas disengagement occurs. The head tank is 6mxl2mx3m... 

The aeration requirements of the deep shaft (vertical shaft bioreactor using flotation technology) are provided by two, 100 hp rotary screw compressors rated at a pressure of 7 kg/m2 (100 psig). Dissolved oxygen (DO) levels of 4 mg/L are maintained in the head tank, and during the startup phase of the plant a DO meter measured a dissolved oxygen concentration of 25 mg/L at the shaft bottom. 

Performance of Ohtsu Paper Company s Deep Shaft Biological Treatment Plant in Japan... 

Wang, L.K. Preliminary Design Report of a 10-MGD Deep Shaft-Flotation Plant for the City of Bangor, PB88-200597/AS U.S. Department of Commerce, National Technical Information Service Springfield, VA, 1987 42 p. 

Otto Aqua-Tech HCR [High-Capacity Reactor] A high-intensity biological treatment process for purifying effluents from food processing, certain industrial processes, and landfill leachate. The waste is circulated rapidly through a vertical loop reactor, and air is injected at the top. Invented at the Technical University of Clausthal-Zellerfeld developed and commercialized by Otto Oeko-Tech. Eleven plants had been installed in Germany and Italy by 1991. See also Deep Shaft, Biobor HSR. 

As project experience has been gained with the super-deep single lift shafts, a munber of realities have emerged. The hoisting plants associated with these single-lift and deep shafts are very expensive to construct, install and maintain. This is especially true of very specialized systems such as the Blair hoisting systems, when employed to depths exceeding 2500 meters. 

Spodumene had been produced from the Preissac-Lacorne deposit by the Quebec Lithium Corp. from 1955 to 1959, supplying ore to LCA s North Carolina plant. Mining was conducted underground, with the initial area developed about 450 m in diameter from a 171 m deep shaft. After mining, the ore was concentrated by flotation (Kesler, 1960) in a mill near the shaft site with a capacity of 2000 mt/day of concentrates. This operation closed when LCA opened their own mine in North Carolina (Kunasz, 1994). 

Fig. 9.4 Soil water content, leaf area, plant water stress, flammability and daily rainfall of mature forest, secondary forest and cattle pasture during the severe 1992 dry season. As deep soil water was depleted during this measurement period (a, b), severe drought stress developed in some trees of the mature forest (d), but the loss of green leaf area was lower in the mature forest than in the secondary forest and cattle pasture (c). Because of this capacity to retain leaves despite severe water stress, the mature forest is rarely susceptible to fire even during a severe dry season such as this (e). Plant-available soil water was measured from 0 to 2 m depth (a) and from 2 to 8 m depth (b) using Time Domain Reflectometry sensors imbedded in the walls of deep soil shafts (Nepstad et al. 1994, Jipp et al. 1998).

Excavations, shafts or pits more than 1.98 m (6 ft 6 in) deep near which men work or pass, must be protected at the edge by guardrails or barriers or must be securely covered (Reg. 13). Guardrails, barriers or covers may be temporarily moved for access or for movement of plant or materials but must be replaced as quickly as possible. 

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