The treatment and disposal of wastewater sludge or biosolids is regulated by the United States Environment Protection Agency (US EPA). It is a catalyst to a sounder environment process in terms of disposing garbage and wastewater sludge. But, it also faces a bigger problem with the control of odor the emanates from facilities that treat and process wastewater sludge. Since biosolids management allows and favors the disposal of wastewater sludge through land application, the public perception and acceptance of its odor remains to be the one challenge it has yet to address.
The odor from biosolids comes from the same bacteria that are responsible from the odor emanating from all the stages of wastewater treatment process. These bacteria attach to dissolved oxygen for respiration, but dissolved oxygen is present in biosolids for only a short period of time, specifically after undergoing mechanical mixing, agitation, and handling. After the dissolved oxygen is expended, the bacteria will turn to oxygen found in nitrates and sulfates.
But there are very little nitrates that the bacteria can turn to, so it will begin to consume sulfates. As a result, the sulfate respiration produces sulfides and mercaptans. Sulfide causes the odor and corrosion problems faced by biosolids.
The number one method of disposing wastewater sludge or biosolids is through land application and landfilling, both of which are on the mercy of communities who can petition for these facilities to close down. This is the reason why wastewater sludge treatment facilities have to strictly follow guidelines set by municipalities. Communities rarely tolerate the presence of treatment plants in their midst. Who would want to wake up smelling biosolids in the air, after all?
Preventing the odor from biosolids management is a tough job to do. Though there are many methods that can be employed, not all of them are readily available and accessible. In fact, many treatment plants have to suffer the ire of the public because of the odor the biosolids and sludge cause.
To keep the bad odor to a minimal, a stable level of nitrates has to be maintained to satisfy the oxygen demands of the sulfur-reducing organisms. Many biosolids management uses the Bioxide Odor Control Process from USFilter. This provides the correct level of nitrate for odor control. It is being used in many biosolids applications.
It might be a long time before public acceptance for biosolids becomes a norm. But with work and dedication from scientists, breakthroughs can open up communities to the benefits of biosolids (even with the very bad odor).