WASTEWATER TREATMENT APPARATUS TO ACHIEVE CLASS B BIOSOLIDS USING CHLORINE DIOXIDE

Abstract

Disclosed herein are systems and processes for treating a Waste Stream comprising biosolids, the Waste Stream provided at varying flow rates and solids concentrations so as to achieve an SOUR of 1.5 mg O.sub.2/g/hr or less and an ORP of at least +300 mV. The system includes a biosolids manipulation device to adjust the volume of suspended solids as a percent of the total volume of the Waste Stream to five (5) percent or less; a chemical oxidant feed device to dose the Waste Stream with an oxidant such as chlorine dioxide, ozone, or similar oxidant, and a treatment vessel associated with said chemical oxidant feed device through which said Waste Stream flows, wherein said chemical oxidant feed device and said treatment device are configured so as to achieve a dose rate between 25 and 200 parts per million of the Waste Stream and substantially complete mixing of the oxidant within 30 seconds of dose delivery in the treatment vessel.

Claims

1. A system for treating a waste stream comprising biosolids so as to achieve a SOUR of 1.5 mg O2/g/hr or less and an ORP of at least +300 mV, the waste stream being provided at varying flow rates and solids concentrations, the system comprising: a biosolids manipulation device to adjust the volume of suspended solids as a percent of the total volume of the waste stream to five (5) percent or less; a chemical oxidant feed device to dose the waste stream with a chemical oxidant, and a treatment vessel associated with said chemical oxidant feed device through which said waste stream flows, wherein said chemical oxidant feed device and said treatment device are configured so as to achieve a dose rate between 25 and 200 parts per million of the waste stream and substantially complete mixing of the oxidant within 30 seconds of dose delivery in the treatment vessel.

2. The system of claim 1, wherein volumetric dimensions of said treatment vessel and said dose rate is such to achieve substantially complete mixing of the oxidant within 10 seconds.

3. The system of claim 1, wherein said chemical oxidant is chlorine dioxide, ozone, and combination thereof.

4. The system of claim 3, wherein said chemical oxidant is chlorine dioxide.

5. A wastewater treatment system comprising: a headworks for receiving raw sewage wastewater having biosolids; a biological treatment station that is in fluid communication with said headworks; a clarifier in fluid communication with the headworks for concentrating biosolids from the raw sewage wastewater, wherein upon being subject to the biological treatment station and clarifier, the wastewater is converted to waste activated sludge (WAS) having a targeted biosolids content; a first conduit for transporting WAS away from the clarifier comprising a treatment zone; and a chemical oxidant feed device in fluid communication with said first conduit so as to dose chemical oxidant and said treatment zone, wherein upon being subjected to the treatment zone the WAS is converted into a treated biosolid sample; wherein said targeted bio solids content is 05.-5 percent, w/v, of the WAS.

6. The system of claim 5, wherein said targeted biosolids content is 1-3 percent, w/v.

7. The system of claim 5, wherein the clarifier is downstream of the biological treatment station.

8. The system of claim 5, further comprising a dewatering device in fluid communication with the first conduit for further removing water from the treated biosolid sample.

9. The system of claim 8, further comprising a second conduit for transporting the concentrated treated biosolid sample from the dewatering device.

10. A method of treating primary wastewater to produce Class B biosolids, the method comprising subjecting the primary wastewater to anaerobic or aerobic digestion to produce digested sludge; and subjecting the digested sludge to dosing of chemical oxidant in a treatment vessel having a treatment zone through which the digested sludge flows, wherein the dosing achieves a dose rate between 25 and 200 parts per million of the digested sludge in the treatment zone and substantially complete mixing of the oxidant within 30 seconds of dose delivery in the treatment vessel. between 25 and 200 parts per million of the digested sludge in the treatment zone and substantially complete mixing of the oxidant within 30 seconds of dose delivery in the treatment vessel; wherein the primary wastewater is not subjected to biological treatment prior to becoming digested sludge.

11. The method of claim 10, wherein the digested sludge comprises a biosolids content of 0.5-5 percent, w/v, when in the treatment zone.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 shows a schematic of a wastewater treatment system that utilizes a chlorine dioxide generating device in a waste activated sludge conduit for purposes of producing Class B biosolids.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0034] Disclosed embodiments in this Disclosure are described with reference to the attached FIGURES, wherein like reference numerals are used throughout the FIGURES to designate similar or equivalent elements. The figures are not drawn to scale and they are provided merely to illustrate the disclosed embodiments. Several aspects are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the disclosed embodiments. One having ordinary skill in the relevant art, however, will readily recognize that the subject matter disclosed herein can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operations are not shown in detail to avoid obscuring structures or operations that are not well-known. This Disclosure is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with this Disclosure.

[0035] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of this Disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein.

[0036] A specific example of a wastewater treatment system for producing a Class B Biosolid sample is shown in FIG. 1. In this specific example, wastewater 108 first enters the headworks 110 and then is transferred to a biological treatment station 115. The biological treatment station 115 functions primarily to remove biosolid-dissociated nutrients (and a low percentage of biosolid-associated nutrients) in the wastewater to produce a nutrient-reduced wastewater sample 116. The nutrient-reduced wastewater sample 116 is transferred to a clarifier 120, where the nutrient-reduced wastewater sample 116 is separated into an effluent component 121 and a WAS component 122. The effluent component 121 is either returned to the headworks 110 or is discarded.

[0037] According to scheme I., the WAS component 122 is transported in a conduit 124 and subjected to a oxidant treatment zone 125 that is fed by an on-site oxidant generator 127 in fluid communication with the oxidant treatment zone 125. The biosolids content of the WAS 122 is between 0.5 to 5 percent solids. The conduit 124 includes an oxidant administration component 143, which may be integrated or separate to the conduit, wherein the chemical oxidant is administered to the WAS in a controlled manner. In particular, the component 143 is configured and associated with the oxidant generator 127 such that the chemical oxidant is administered to WAS to achieve dispersal of the chemical oxidant in the WAS within 30 seconds or less, 20 seconds or less, 15 seconds or less, 10 seconds or less, 5 seconds or less, or 2 seconds or less.

[0038] Following, oxidant treatment, the WAS 122 is transported to a dewatering device 140 (such as a belt filter press or centrifuge device) where more water is removed from the WAS to achieve a concentrated biosolids sample 141 having 12-30 percent biosolids. The, concentrated biosolids sample achieved prior to the dewatering station 140 has a higher ORP and lower SOUR.

[0039] According to an alternative embodiment, scheme II, raw wastewater is delivered to a digester 184, either prior or after biological treatment. The raw wastewater is treated in the digester 184 to produce digested sludge 192. The digested sludge may have 0.5 to 5 percent biosolids. A conduit 164 transports digested sludge 192 away from the digester 184. The conduit 164 includes a oxidant treatment zone 155. An oxidant generator 157 deliver the predetermined dosages to the oxidant treatment zone 155 at the mixing component 163. The mixing component 163 is configured similar to component 143 as discussed above. The digested sludge 192 is transported to a dewatering device 140, where further water is removed to obtain a concentrated biosolids sample 141 that may be classified as Class A or Class B biosolids.

[0040] While various disclosed embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Numerous changes to the subject matter disclosed herein can be made in accordance with this Disclosure without departing from the spirit or scope of this Disclosure. In addition, while a particular feature may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.

[0041] Thus, the breadth and scope of the subject matter provided in this Disclosure should not be limited by any of the above explicitly described embodiments. Rather, the scope of this Disclosure should be defined in accordance with the following claims and their equivalents.

[0042] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms including, includes, having, has, with, or variants thereof are used in either the detailed description and/or the claims, such terms are intended to be inclusive in a manner similar to the term comprising.

[0043] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0044] The disclosure of any cited reference, including related applications, is incorporated herein in its entirety to the extent not inconsistent with the teachings herein.