Discussion of Muddy Surface Settling of Xiaolangdi Reservoir

Sediment settling velocity is an important parameter in particle suspension and indispensable link of hyperconcentrated flow as well as basic theory support for efficient sediment transport of Xiaolangdi Reservoir. This paper has adopted current sediment sample in Xiaolangdi Reservoir to take still water settling experiment, observed carefully silt sediment distribution during different settling duration under various initial concentrations, analyzed common settling velocity calculation method, and adopted settling duration curve method as calculation method to obtain a constant settling velocity of free settling section. Typical settling velocity that is obtained from experiments makes supplement and fitness to settling velocity formula of the existing groups of sediment sample, amends the formula coefficient, further explore the settling characteristics and settling velocity of fine particle mixed viscous sediment with water concentration change, and meanwhile this paper researched settling distance impact on settling velocity, existing sediment group settling transition to mesh settling critical transition silt concentration of Xiaolangdi Reservoir.

Treatment of Wine Distillery Waste in UASB Systems – Feasibility, Alkalinity Requirements and pH Control

Grape wine distillery waste developed a pelletised sludge bed in a UASB system. Product formation along the line of flow in the pelletised bed was similar to that when treating a pure carbohydrate, apple juice waste. Pelletised sludge production was about 0.14 mgVSS/mgCOD removed (as against 0.42 mgVSS/mgCOD removed for apple juice waste), indicating a low influent COD carbohydrate fraction. The pellets were not as compact as with apple juice waste and were smaller (< 2 mm). The distillery waste COD ranged from 20 000 to 30 000 mg/ℓ. An appreciable amount of H2CO3*alkalinity was generated internally due to deamination of proteins and removal of organic salts. Provided the system was operated with a recycle from the effluent to influent at a recycle ratio sufficiently high to dilute the base influent COD to an effective influent COD (CODe) < 2000 mg/ℓ, sufficient of the H2CO3*alkalinity generated internally was recycled to maintain a minimum sludge bed pH > 6.6. Recycle ratios as high as 33:1, reducing the base influent COD of 27 000 mg/ℓ to a CODe of 790 mg/ℓ, did not adversely affect COD removal. No nitrogen, phosphate or trace element supplementation was required. COD removal was greater than 94 percent for COD loading rates up to the maximum of 15 kg/(m3 sludge bed.d); the maximum COD loading rate was fixed by gas lifting pellets in to the settling section, not by process failure.