Most treatment and disposal processes of biosolids for environmental management are regulated and are subject to compliance to the rules and regulations set by governing agencies. However, such regulations and rules are not applicable to the reduction of odor in biosolids production. There is no regulated process that is required to be used for the production of biosolids to reduce and remove odor caused by processing sewage sludge.
This is a huge problem for treatment plants and for municipal waste management because odor elimination remains to be the biggest issue for the public acceptance of biosolids. And why do treatment plants and municipalities need the acceptance of the community? The disposal method favored by the current Part 503 regulations of the EPA is the land application of biosolids.
This means that the approval of communities is needed for the presence of biosolids in the soil surrounding them. Remember that unless it is a Class A EQ biosolids, the material could contain pathogens and other harmful chemicals that could potentially contaminate the water sources.
Though in large part, applying biosolids is done way outside the possibility of it spilling into the water sources, communities don’t really accept this fact. What they do know is that the land application of biosolids post a threat to their water and that the odor affects their daily lives.
There are two ways that treatment facilities could manage this: through odor prevention or complete odor removal.
Odor-causing compounds could be formed in sludge and biosolids. This needs to be prevented in order to contain the odor. To do this, a stable level of nitrates must be maintained to satisfy the oxygen demands of the sulfur reducing organisms present. Instead of the sulfates being consumed, the nitrate acts as substitute. It is also used in respiration by these bacteria and results in the production of odorless and harmless nitrogen gas.
The Bioxide process encourages a unique group of bacteria that consumes existing sulfide in the presence of nitrate. These are known as lithotrophic, which literally means “rock eaters.” What these bacteria do is eat sulfide for energy using nitrate as the fuel for the process. This removes the odor-causing compounds.
Bioxide solution can be utilized during the many phases of the biosolids thickening process. It depends on the facility where the solution is added and at what point is the odor elimination needed. For example, during transport and final storage, the solution us sprayed on the thickened biosolids and mechanically mixed during the transport of the material.