A company is using 2 outdoor ponds to reduce organic material from a 500. gallons/hour wastewater stream. In the current situation, the ponds have a surface area of 1 acre (first pond) and 3.1 acres (second pond) (1 acre = 43,560 ft2) and both have an average depth of 6.0 ft. Arranged in series with the outflow from the first pond feeding the second pond, the system removes 95% of the organic material by mass. Evaporation of water is 25 gallons per acre per hour. Since the reaction is highly dependent on oxygen levels, both ponds are aerated, and the bubbling thoroughly mixes the water in each pond. The chemical decay reaction is first order. a. (4 points) Estimate the decay coefficient of the organics in the existing pond set. b. (6 points) The EPA has just lowered the release criteria, and the company must improve treatment until 98% of the organic material is removed. You resolve to reach this new level of treatment by increasing the pond size. An excavator is ready to start digging new pond volume, but digging costs money, based on the volume of dirt removed. For geological reasons, any new pond volume may not be dug deeper than the existing 6.0 ft. For the lowest cost solution, should the excavator:

Adozen is 1221/12 = 1.751.75 x 12 = 21therefore, 1.75 is the answer.

The answer to your question really depends on three things: how much water you have, how cold it is to start out, and how cold the things around it are. water actually freezes when it gets to 32 degrees fahrenheit (0 degrees celsius), but the time it takes to get there may be different.  let's start with the first. if you take two glasses, and fill one with a tiny bit of water, and the other about halfway, then put them both in the freezer, the one with less water will freeze first (you can try this at home, but i recommend using plastic cups and not glass ones).  now let's move on to the second part. let's say you have two glasses, and you fill one with really cold water that has been in the refrigerator, and the other with really hot water from the sink. if you put both of them in the freezer, the one that started out colder will freeze first.  for the third part, let's imagine that you have two glasses with the same amount of water in them, and the water is at the same temperature. imagine putting one outside on a really really cold day in georgia, and having a friend in alaska put one outside on the same day. since it would be so much colder in alaska, the glass of water there would freeze before yours.  so, if you took a tiny bit of really cold water in a glass, and put it outside on a cold day in alaska, it would freeze a lot faster than a big glass of hot water outside on a cold day in georgia.