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The Neutralizer® is a two-stage chemical treatment system. Untreated biosolids, usually consisting of Waste Activated Sludge (WAS), travel through the Neutralizer® system where they are treated by a patented chemical injection system. The processing time is eight hours and the final product is a treated, virtually odor-free residual suitable for use as a commercial fertilizer.


The Neutralizer® Process

Step 1 – Sludge Delivery & Thickening

WAS Pumps feed sludge from the clarifier, typically at 1-2% solids, into the Neutralizer® Sludge Receiving & Polymer Addition Skid at a monitored and controlled rate. The polymer injection system adds polymer to the sludge to optimize thickening. The sludge and dilute polymer mixture is sent to the stir/flocculation tank on the Sludge Thickening Skid where Huber disk thickeners thicken the sludge to 4% solids. Thickened sludge is then sent to the sludge hopper where it accumulates for chemical treatment.


Step 2 – Neutralizer® Chlorine Dioxide Addition & Acidification

Sludge is pumped from the sludge hopper to the Sludge Processing Skid where chemical metering pumps deliver flow-controlled doses of sodium chlorite and sulfuric acid into BCR’s chlorine dioxide (ClO2) Generating System, a patented technology for onsite production of chlorine dioxide. The system then injects the chlorine dioxide into the thickened sludge stream and pumps the mixture into the Sludge Processing Tanks. The sludge is retained in the Sludge Processing Tanks for at least one hour.


Step 3 – Neutralizer® Sodium Nitrite Addition & pH Adjustment

In the second stage of chemical treatment, sulfuric acid (H2SO4) is pumped into the Sludge Processing Tanks, dropping the pH to an optimal level. Then, sodium nitrite (NaNO2) is added to the Sludge Processing Tanks for an additional six hours to ensure the required pathogen reduction for Class A/EQ and Volatile Solids Reduction (VSR) for Vector Attraction Reduction (VAR) are met. Prior to dewatering, sodium hydroxide (NaOH) is added to the disinfected sludge in to raise the pH of the final product, typically to a pH of 6.0 to meet the end user’s needs.


Step 4 – Dewatering & Phosphorus Removal

Neutralizer® treatment enhances dewaterability, resulting in reduced polymer consumption and higher total solids in the end product, which in turn leads to reduced operating and hauling costs. The Class A/EQ residuals are dewatered using standard technology such as a centrifuge, screw press, or belt press. Ferric sulfate (Fe2(SO4)3) is added to the disinfected sludge immediately prior to dewatering to aid in phosphorous removal. Phosphorous binds with the iron in the ferric sulfate and this iron phosphate is retained within the dewatered residuals, effectively removing phosphorus from the wastewater treatment facility.


Step 5 – End Product Management

Neutralizer® produces superior Class A/EQ residuals that allow for expanded disposition options based on their nutrient content and lack of foul odors. As part of our Whole Solution offering, BCR can assume long-term responsibility for the transportation and end product management of material treated at any Neutralizer® facility, eliminating client liability for end product management and disposition.

Neutralizer® Benefits

The Neutralizer® delivers numerous key advantages over traditional Class A and Class B biosolids management technologies. The benefits of the Neutralizer® system include:

Reduced capital costs: Neutralizer® requires substantially less upfront capital to implement compared to other Class A biosolids management options. The Neutralizer® system reduces infrastructure complexity by eliminating the need for digestion and sludge holding facilities.

Reduced operating costs: The Neutralizer® solution uses chemistry rather than energy-intensive biological or thermal processes to achieve Class A/EQ standards. The end result is a reduction in energy costs, polymer costs, and sludge disposition costs.

Reduced energy requirements: By eliminating the need for digestion and other energy-intensive systems, Neutralizer® installations typically experience substantial energy savings, often reducing energy consumption by 90% or greater. Energy savings translate to a reduction in the wastewater treatment plant’s carbon footprint.

Elimination of odors issues: Elimination of odors issues: Neutralizer® effectively eliminates odor issues beginning with onsite treatment and continuing through transportation and end product disposition. Neutralizer® chemical treatment eliminates odorous compounds by oxidizing sulfides, sulfates, and mercaptans.

Improved product quality: Eliminating digestion produces a more consistent end product and enhances nutrient retention in the biosolids. The Neutralizer® also enhances dewatering, resulting in a high quality, higher % solids Class A/EQ product. Eliminating odors from the biosolids increases the appeal of the product and increases disposition options.

Enhanced regulatory compliance: Neutralizer® simply and consistently meets U.S. EPA regulatory requirements for beneficial reuse of Class A/EQ biosolids in accordance with Title 40 Code of Federal Regulations (CFR) Part 503. Meeting Class A/EQ standards substantially expands the number of potential disposition options and creates the potential for producing a marketable, valuable end product that can be registered as a commercial fertilizer.

Neutralizer® Class A Residuals

The Neutralizer® produces a consistent, fertilizer grade residual that expands the number of viable end use options. Neutralizer® treated residuals meet Class A/EQ biosolids standards in accordance with the United States Title 40 Code of Federal Regulations (CFR) Part 503 through Alternative 6: Biosolids Treated in a Process Equivalent to a Process to Further Reduce Pathogens (PFRP). Neutralizer® meets Vector Attraction Reduction (VAR) requirements typically through Option 1: 38% Reduction in Volatile Solids Content, although VAR can also be achieved through other options. The residuals may be registered as a commercial fertilizer with the Department of Agriculture in various states.

By avoiding digestion, Neutralizer® residuals retain a higher nutrient content, making them a highly desirable beneficial reuse product. When applied as a soil amendment or fertilizer, the residuals provide an excellent source of nitrogen and organic materials. The pH of the residuals can be adjusted to meet client needs, expanding the number of viable disposition sites.

Neutralizer® treatment oxidizes sulfides, sulfates, and mercaptans, producing an end product free from foul odors. The odor-free nature of Neutralizer® residuals further increases the desirability of this Class A/EQ product and expands viable application sites to those in close proximity to residences. In addition, Neutralizer® residuals reduce phosphorus leaching, which poses a threat to ground or surface water. Neutralizer® residuals have an extremely low P index (measurement of phosphorous leachability).

Benefits of Neutralizer® Residuals

Neutralizer® residuals deliver numerous key advantages when compared to other Class A products produced through traditional management technologies:

Elimination of odor issues: Neutralizer® effectively eliminates odor issues associated with end product disposition. Neutralizer® residuals have a pleasant, earthy smell. Fertilizer application can take place in close proximity to residences without generating nuisance odors or odor complaints.

Expanded disposition options: Regulatory restrictions significantly limit land application of Class B material compared to the Class A/EQ residuals. Neutralizer® produces a pH-adjustable, fertilizer grade product that greatly expands the number of viable end use options which include fertilizer and soil amendment options.

Simplified regulatory compliance: BCR maintains open communication with the U.S. EPA and state environmental agencies to ensure our end products achieve current and future regulatory compliance.

Reduced nutrient loss: Light textured (sandy) soils possess a low cation exchange capacity (CEC), resulting in nutrient loss. Adding Neutralizer® residuals to the soil raises the CEC and enables the soil to better hold onto nutrients like potash and nitrogen which would otherwise leach out of the soil.

Improved plant survival and growth rates: Organic matter improves the aggregate strength of soils, making the soil more resistant to compaction, improving root penetration, and helping plants establish and sustain growth. Neutralizer® residuals add necessary organic material back to the soil.