PHYSICO CHEMICAL PROCESSES FOR WATER AND WASTE WATER TREATMENT
ASSIGNMENT NO: 1
- One lake, in permanent campus is rich in fishes of variety Pond murrel (Channamaurulius). The lake is near to the irrigation land in Katragayalungta village. The farmers in the village are using water from the tributary stream which is originated from Tada water falls. The water stream got polluted with arsenic contamination by the industries while streaming. The water stream flows at rate of 3 m3/s with arsenic concentration of 0.0015 mg/L. The farmer starts withdrawing 1 m3/s of the water stream to irrigate the land. During irrigation, the water picks up arsenic from the salts in the soil. One-half of the irrigation water is lost to the ground and plants, and the other half is returned to the tributary. The irrigation run-off which is sent to the lake contains 1 mg/L of arsenic. The fishes in the lake are sensitive to arsenic levels over 10µg/L. The farmer agrees not to use more water than will keep the stream arsenic level below this critical concentration. How much water can the farmer withdraw from the stream to use for irrigation?
- A meat processing plant is making packed meats, that should contain fat 15%. The source of the meat is goat contains fat of 23% and beef contains fat of 5%, what are the proportions in which these should be mixed to get 100 kg of meat?
- Penicillin is recovered by contacting the fermentation broth with an organic solvent in an extraction process. The penicillin has greater affinity to the organic solvent than aqueous solution. The Figure given below shows the process overview. Determine the mass fraction of penicillin in the exit after extraction. Density of aqueous solution is 1 g/cm3and thedensity of the organic solvent is 0.6 g/cm3
Figure: Extraction process
- A lake contains V = 2 x 105 m3 of water and is fed by a river discharging Qupstream = 9 x 104 m3 /year. Evaporation across the surface takes away Qevaporation = 1 x 104 m3 /year, so that only Qdownstream = 8 x 104 m3 /year exits the lake in the downstream stretch of the river. The upstream river is polluted, with concentration C = 6.0 mg/L. Inside the lake, this pollutant decays with rate K = 0.12/year. Find the concentration of pollutant in downstream (Take volume V of the entire lake as the control volume.Assume steady state condition)
- Clean air is blowing into the box (See figure below) along with one of its sides with a speed of 4 m/s. Sulphur di-oxide, an air pollutant with a reaction rate k = 0.2/h is emitted into the box at a total rate of 10 kg/s. Find the steady-state concentration if the air is assumed to be thoroughly mixed.
Figure: Box like representation of air velocity over a city
- A manufacturing process uses 100 kg/month of Solvent S to clean machine parts. Solvent S is volatile and 15% of it is lost to the atmosphere. 40% is recovered for recycling each month. The remainder leaves the plant in wastewater. What is the average concentration in the wastewater if the average flow is 10 m3 /d?
- A waste stream (2m3/s) containing a biodegradable constituent (Element X) with a concentration of 25 mg/L is discharged to a river (10 m3/s). There isn’t any Element X in the river upstream. After two days of travel downstream, a sample of the river water is collected. What is the concentration of element X? Assume k = 0.2/d. (Hint: Determine the reaction rate model by looking at the units of k.)
- Due to algal growth in a water supply reservoir in a neighbourhood, the water has acquired an unpleasant taste. The compound is non-degradable, and the water utility has decided that the best way to deal with the situation is simply to flush the contaminant out of the system. The reservoir contains 11,000 m3 of water, and the proposal is to pump 300 m3/h of clean water through the system and discharge the effluent to the sewer system until 95% of the offending compound has been removed. If the reservoir is intensely mixed, how much flushing water will be required?
- Nischal is filling her bathtub with a capacity of 300L but he forgot to put the plug in. if the volume of water for a bath is 1m3 and the tap is flowing at 1.32 L/min and the drain is running at 0.32 L/min, how much long it takes to fill the tub is full and does not flood the house, how much water will be wasted? Assume the density of water as 1000 kg/m3
- A continuous stirred tank has a volume of 5L. It contains 0.5 L of dirty water with a concentration C0=100g/L of some toxic substance represented by variable X. At some moment ,2.5 L of clean water is added. a.Calculate the concentration of X after adding the fresh water? b.In order to be able to clean this water using microorganisms,the concentration of X needs to be lower than 0.1g/L.Is it possible to add a sufficient amount of water to the tank such that the concentration of X is below this limit?