Biosolids
Process
The biosolids treatment method is a chemical/mechanical wastewater treatment method for wastewater streams and/or industrial wastewater treatment plant process liquid streams containing suspended solids. It comprises removing all or a portion of the suspended solids in the influent entering a bioreactor forming a filtrate with reduced solids and BOD to reduce the load on the bioreactor, but with sufficient dissolved and suspended solids suitable to support bacteria and microbe bioreduction of nitrogen, phosphorus, BOD, and other nutrients.
SO2 is then injected into the suspended solids at a pH and dwell time to generate sufficient sulfurous acid with free SO2, sulfites and bisulfites to:
The SO2 treated solids fraction is then separated from the liquid fraction using mechanical separators.
The liquid fraction is then transferred into the bioreactor for bioremediation to remove nitrogen, phosphorus, and nutrients to the degree required to meet wastewater treatment plant discharge requirements for land application or open stream discharge.
The solids fraction is then allowed to dry to create a disinfected, reduced metal Class A biosolid with less than ten percent weight water and a BTU content comparable to wood.
The biosolids treatment method is a chemical/mechanical wastewater treatment method for wastewater streams and/or industrial wastewater treatment plant process liquid streams containing suspended solids. It comprises removing all or a portion of the suspended solids in the influent entering a bioreactor forming a filtrate with reduced solids and BOD to reduce the load on the bioreactor, but with sufficient dissolved and suspended solids suitable to support bacteria and microbe bioreduction of nitrogen, phosphorus, BOD, and other nutrients.
SO2 is then injected into the suspended solids at a pH and dwell time to generate sufficient sulfurous acid with free SO2, sulfites and bisulfites to:
- Disinfect and self-agglomerate the suspended solids
- Acid leach heavy metals contained in and on the suspended solids into solution for subsequent removal and separation
- Condition the suspended solids for subsequent dewatering by shedding water upon separation and drying
The SO2 treated solids fraction is then separated from the liquid fraction using mechanical separators.
The liquid fraction is then transferred into the bioreactor for bioremediation to remove nitrogen, phosphorus, and nutrients to the degree required to meet wastewater treatment plant discharge requirements for land application or open stream discharge.
The solids fraction is then allowed to dry to create a disinfected, reduced metal Class A biosolid with less than ten percent weight water and a BTU content comparable to wood.
Benefits
Results
Influent Reductions
- Reduces load on the biological reactor, expanding capacity
- Produces drier, odorless solids, generally resulting in great than 30% weight haulage savings
- Eliminates anaerobic digestion and associated H2S production
- Disinfected Class A biosolids (<1,000 MPN and reduced heavy metals) suitable for land use
- Biosolids with pH adjusted as suitable for land use
- Flexibility to separate disposal of heavy metals and phosphates
- As a new biosolids treatment technology, it may qualify for special grant funding
Results
- Dried Class A biosolids
- Fecal coliforms <1,000 MPN
- <10% by weight water
- pH ~4.5 (lime adjustable)
Influent Reductions
- 25-50% Nitrogen
- 50-80% Total suspended solids
- 50% Phosphorus