Animal waste and human waste are treated far differently, and therein lies a tale. The bottom-line reason for the difference, in the main, is cost. But it’s important to keep in mind the fundamentals here: animal waste is not all that much different than human waste.
The Wisconsin State Journal has a lengthy article entitled “Tracking a Rising Tide of Waste,” addressing regulatory issues surrounding land application of animal manure:
Wisconsin is churning out permits for industrial-scale farms to spread millions of gallons of manure on state fields but provides little oversight after that, inspecting them only once or twice every five years, a Wisconsin State Journal investigation has found.
Groundwater contamination is the main consequence the article covers, although nutrient pollution is another one.
Why is it that we spend big bucks on facilities to transport and treat human sewage, but only a fraction of that amount on treating animal waste? One reason is historical. Agriculture has always gotten something of a break on environmental control issues. Things evolve, and the great epidemics of the past do not occur today, in part, because we treat human waste they way we do. Agricultural waste has taken a while to come to the fore as a problem, but we know more now, and rural areas are disappearing.
In addition, we need food, after all, and there are powerful business and political interests at work here. They don’t call it agribusiness for nothing. And, many of those in the upper echelons recognize that it is important to keep food costs within certain limits, lest they lose their perches in those upper echelons. So, the politicos are susceptible to the argument that pollution control can make food cost more.
There are many arguments against business as usual in our meat production methods. These include requirements for tremendous quantities of water, compared to producing vegetable protein, and production of heat trapping gases, as reviewed previously, here. Animal waste issues are going to be around for a long time.