A company has been discharging its waste into a holding pit for a long time. For

Question

A company has been discharging its waste into a holding pit for a long time. For the last several years, the pit has been full and overflowing into a local river. The waste concentration has been nearly constant at 10 mg/L of the pollutant of interest. At this concentration, there have been no adverse effects on the stream. Suddenly, there is a process change and the contaminant in the waste stream goes up to 100 mg/L. Given that the waste stream flow rate is 100,000 L/day and the holding pit volume is 1.0 million liters, determine the concentration of the pit's overflow stream after 10 days.

Explanation / Answer

Dealing with waste is a challenge common to all human societies.Nature makes no waste: in healthy ecosystems, one species’ waste becomesfood for the next, in an endless cycle. Modern societies interrupt this cycle inthree ways.First, technology has created a wide range of substances that donot exist in nature. Human discards are thus increasingly comprised of plastics,metals, and natural materials laced with hazardous substances (for example,bleached and inked paper), which, in many cases, are difficult or impossible fornatural ecosystems to break down.Second, industrial societies use and dispose of much more materialper person than their predecessors, and than their counterparts in the lessindustrialized world.Third, rapid population growth increases the number of people andthe total amount of waste generated. As a result, the global ecosystem isoverwhelmed, both quantitatively and qualitatively, with what we discard.Ultimately, human societies rely on the natural environment for all their materialneeds, including food, clothing, shelter, breathable air, drinkable water, and rawmaterials for manufacturing and construction. At the same time, all humandiscards go to the environment.When humans were few and of limited technological capability, wecould afford to ignore the relationship between these two processes. Now that wedominate the global ecosystem, that is no longer the case. At the same time thatwe are confronted with rapid destruction and growing scarcity of naturalresources — deforestation, declining fisheries, contaminated groundwater,

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.