environmental engineering

Please explain What will happen to Ca(OH)2 solid when it is placed in a saturated solution of calcium hydroxide.

environmental engineering

Please explain why

plug flow reactors are more “efficient” than complete mix flow reactors.

A typical drywall finisher works 45 hours per week for 16 weeks of the year and 40 hour per week for 32 weeks of the year, and gets 4 weeks off in the form of vacation, holidays, and sick leave (for which the drywall finishers are paid for 40 hours per week). The typical drywall finisher is paid $25.78 per hour. The employer must comply with the overtime requirements in the Fair Labor Standards Act. Determine the wages paid to a typical drywall finisher and the number of billable hours during a one-year period. Assume that all hours are billable except holidays, vacation, and sick leave

A simply supported beam with a span of 26 FT is used to carry a service dead load (including self-weight) of 1.65 KLF and a service live load of 3.3 KLF and is reinforced with 4-#9 bars. The beam has a width b of 14 IN, an effective depth of 24.5 IN., and a height of 27 IN. The material strengths are f’c = 4000 PSI and fy = 60 KSI. The immediate deflection due to live load is limited to L/360. Does the beam meet these limits?

Scientists detected COVID-19 in Boston’s sewer system. The city decides to disinfect the effluent of its wastewater treatment plant. Please describe the procedures and the required chemical agents to measure chlorine concentration in water.

Essay explaining your understanding of the profession of Transportation Engineering/Planning and how you plan to contribute to the excellence of the profession. This essay should be no longer than two typewritten pages, but no less than one single-spaced.

I need 2 pages minimum please

A city is considering a reservoir water as its new drinking water source. As a result, the city council wants to know how good the reservoir water is to serve this potential purpose. Assume you are the chief engineer of the city utilities; please provide a list of water quality parameters need to be tested and the corresponding testing methods.

Assuming a cost of AED 1.5/Liter to pump and distribute water in a municipal supply system that loses (P) of its water because of leaks, how much money is wasted annually for a city of (X) million people with a per capita demand of 300 Liters/day?

where, X = 21.0 millions P = 2%

The inactivation of a pathogenic bacterium by HOCl follows Chick’s law, i.e. the rate of death is a 1^st order reaction, where the death rate is proportional to the number of bacteria at any time. 90 % of the pathogen are killed after 5 min for a constant free chlorine concentration of 2 mg/L (assume low pH, where all free chlorine is present as HOCl).

a)      (9%) What is the percent kill after 10 min at the same HOCl concentration?

b)     (8%) What percentage of the free chlorine would be present as HOCl (not OCl^-) at pH8 if the pK_a for hypochlorous acid is 7.5?

c)       (3%) Why and how would the disinfection time have to change to still achieve 90 % kill of the pathogen at pH 8 at the same free chlorine concentration? (no need to calculate, discuss in terms of order of magnitude)

Within a study watershed there are six precipitation gauges with the following average annual rainfall [mm] at the following elevations [m]:

GaugeElevations = [442, 548, 736, 770, 852, 1031]

GaugePrecipitation = [1392, 1246, 1495, 1698, 1717, 1752]

Topographic analysis of this watershed gives the following distribution of its area with elevation:

AreaElevations = [200, 400, 600, 800, 1000, 1200, 1400, 1600]

AreaFraction = [0.0, 0.028, 0.159, 0.341, 0.271, 0.151, 0.042, 0.008]

Where the AreaElevations are the upper end of that area's elevation range. For example, 2.8%, of the basins area has an average elevation of 300m (i.e. between 200m and 400m). Given this information, estimate the average annual precipitation that this watershed receives.

An equal-tangent crest vertical curve connects an initial grade of +2.5% and a final grade of –0.5%. The curve is designed for 70 mi/h and the station of the PVT is 132+62 and is at elevation 833 ft. What is the station and elevation of the curve's high point?

A trapezoidal wall 2.75m in height has a bottom width 5m and upper width 4.5m. Determine quantity of cement and sand of mortar for CHB Laying using class A mixture for 10x20x40CHB