Pollution in the Mahanadi river has been constant for several years with mean u=34ppm and
standard deviation of 8 ppm. Hindalco company who discharge liquids into the river is now
claiming that they have lowered the average with improved filtration devices. Assume that the
sample of size 50 gives a mean of 32.5ppm. Perform a hypothesis test at 1% level of
significance and state your decision.
Answers
Answer:
Explanation:
The Orissa State Pollution Control Board, or ospcb, has issued the Hirakud Aluminium Smelter a show-cause notice after its team of experts reported that the plant is releasing untreated wastewater, laced with toxins such as cyanide and fluoride, into the state's largest river, the Mahanadi. The waste discharge has damaged paddy fields and vegetation in the area.
ospcb is now vetting Hindalco's reply submitted on December 3, 2008. If the board is not satisfied with the response, it could ask the plant to close.
Gross violation
Hindalco's Hirakud smelter produces aluminium from alumina--100,000 tonnes a year. This results in production of waste containing cyanide and fluoride.While cyanide is a killer, fluoride causes vegetation to shrivel and shed leaves. Drinking fluoride-contaminated water can cause bone deformities.
During an inspection on September 27, 2008, the ospcb team found that the plant discharged untreated wastewater directly into adjoining waterways. At two places it released effluents into Khajur Nala, a tributary of the Mahanadi. The third outlet opened into a stormwater drain that joins the river. Untreated effluents from the smelter unit's power plant was also being released into Khajur Nala, the team noted in the report. This contravenes the Water (Prevention and Control of Pollution) Act, 1974, which stipulates that no company can discharge industrial wastewater outside its premises and must re-use after treating it in an effluent treatment plant.