Method and Apparatus to Reduce Wastewater Greenhouse Gas Emissions, Nitrogen and Phosphorous Without Bioreactor Processing

Abstract

This invention relates to a treatment method and apparatus directed to improving water quality, increasing net energy production, and reducing greenhouse gas emissions without employing bioreactor processing for waters containing suspended organic solids, PPCPs, PFAS, negative colloids, heavy metals, phosphates, nitrates, carbonates, silicates, chlorides and sodium ions. It employs SO.sub.2, sulfites and bisulfites to self-agglomerate suspended organic solids with sorbed PFAS and PPCPs, and acid leach heavy metals into solution. Subsequent liming filtration separates of metal hydroxides and insoluble calcium salts while chemically conditioning the separated organic solids for gasification or burning. The second filtrate is then exposed to ultra violet light for pathogen disinfection, and exciting sulfites to remove nitrates, and degrade PFAS and PPCPs to form a disinfected metal free salt balanced reclaimed wastewater with reduced PFAS, PPCPs, pathogens and negligible nitrogen and phosphorous.

Claims

1. A treatment method for waters containing suspended organic solids, PPCPs, PFAS, negative colloids, heavy metals, phosphates, nitrates, carbonates, silicates, chlorides and sodium ions comprising: a. adding SO.sub.2 or sulfurous acid with free SO.sub.2, sulfites and bisulfites to the wastewater at a pH and dwell time to: i. acid leach heavy metals contained in and on the suspended organic solids into the SO.sub.2 or sulfurous acid solution for subsequent removal and separation, and ii. precipitate the suspended organic solids and sorbed PPCPs, PFAS, and negative colloids, cobalt sulfite, nickel sulfite, and lead sulfite; b. separating the suspended organic solids and sorbed PPCPs, PFAS, negative colloids, and metal precipitates from the filtrate solutions of SO.sub.2 or sulfurous acid and allowing them to dry to create metal precipitates, and a biofuel with less than 10% by weight water and a BTU content between 6,000 and 9,000 BTU/lb. for gasifying or combustion to produce power or energy with greenhouse gas emissions less than emitted by landfilling and/or anaerobic digestion; c. adding lime to raise the pH above 9 of the SO.sub.2 or sulfurous acid filtrate solution to precipitate calcium phosphate, calcium sulfate, calcium carbonate, calcium silicate and metal hydroxides for filtration removal leaving a second filtrate with PFAS, PPCPs, pathogens, nitrates, sulfites, chlorides, and sodium and monovalent ions; and d. exposing the second filtrate to ultra violet light at the wave length and dwell time for pathogen disinfection, and exciting the sulfites to reduce nitrates to nitrogen gas and degrade PFAS, and PPCPs, forming a disinfected metal free salt balanced reclaimed wastewater with degraded PPCPs, PFAS and reduced nitrogen, phosphorous.

2. The treatment method according to claim 1, wherein gasification produced biochar and is land applied to adsorb atmospheric carbon dioxide.

3. A treatment apparatus for waters containing total suspended organic solids, PPCPs, PFAS, negative colloids, heavy metals, phosphates, nitrates, carbonates, silicates, chlorides and/or sodium ions comprising: a. means for adding SO.sub.2 or sulfurous acid with free SO.sub.2, sulfites and bisulfites to the wastewater at a pH and dwell time to: i. acid leach heavy metals contained in and on the suspended organic solids into the SO.sub.2 or sulfurous acid solution for subsequent removal and separation, and ii. precipitate the suspended solids and sorbed PPCPs, PFAS, negative colloids, metal precipitates cobalt sulfite, nickel sulfite, and lead sulfite; b. means for separating the suspended organic solids and metal precipitates from the solutions of SO.sub.2 or sulfurous acid and allowing the organic solids to dry to create a biofuel with less than 10% by weight water and a BTU content between 6,000 and 9,000 BTU/lb.; c. means for gasifying or combustion the biofuel to produce power or energy with greenhouse gas emissions less than emitted by landfilling and/or anaerobic digestion; d. means for adding lime to raise the pH above 9 of the SO.sub.2 or sulfurous acid filtrate solution to precipitate calcium phosphate, calcium sulfate, calcium carbonate, calcium silicate and metal hydroxides for filtration removal leaving a second filtrate with PFAS, PPCPs, nitrates, sulfites, chlorides, and sodium and monovalent ions; and e. means for exposing the second filtrate to ultra violet light at the wavelength and dwell time for pathogen disinfection, exciting the sulfites to reduce the nitrates to nitrogen gas and degrading PPCPs and PFAS, forming a disinfected metal free salt balanced reclaimed wastewater with reduced PPCPs, PFAS, pathogens and nitrogen and phosphorous.

4. The treatment apparatus according to claim 3, wherein the means for gasifying comprises a gasifier or plasma gasifier, and the means for combustion comprises a co-fired boiler or kiln.

5. The treatment apparatus according to claim 3, wherein the means for adding sulfurous acid comprises a sulfurous acid generator combusting raw sulfur producing SO.sub.2 for injection into wastewater and/or-separated solids.

Description

DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 illustrates the source of greenhouse gas emissions for a typical wastewater treatment plant.

[0054] FIG. 2 illustrates the percentages of greenhouse gas emissions from various wastewater treatment plant processes.

[0055] FIG. 3 illustrates how suspended solids substrates adsorb PPCPs, pathogens, heavy metals, which are released when the substrate is broken down by microbes.

[0056] FIG. 4 illustrates salt balancing with bi-valent ions to repeal and leach away from the roots monovalent salts, retaining needed plant nutrients.

[0057] FIG. 5 illustrates the fuel value of anaerobically digested sludge vs. separated primary solids.

[0058] FIG. 6 illustrates acid cation agglomeration of colloidal bio solids without polymers.

[0059] FIG. 7 illustrates separated bio solids drying energy usage for polymer separated sludges vs. chemically dried separated solids.

[0060] FIG. 8 illustrates an example of a flow diagram removing upfront suspended solids with SO.sub.2 for chemical drying, and conditioning the lime adjusted filtrate with UV excited sulfites to reduce N and P without bioremediation.

[0061] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0062] An example of the present invention will be best understood by reference to the drawings. The components, as generally described and illustrated, could be arranged and designed in a wide variety of different configurations. Thus, the description of the embodiments is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention.

[0063] FIG. 1 illustrates the source of greenhouse gas emissions for a typical wastewater treatment plant.

[0064] FIG. 2 illustrates the percentages of greenhouse gas emissions from various wastewater treatment plant processes illustrated in FIG. 1. Land application produces 37% of the greenhouse gas emissions followed by anaerobic digestion producing 35% of the greenhouse gas emissions. Gasification/combustion of the upfront separated suspended solids avoids both these processes to significantly reduce greenhouse gas production while generating power.

[0065] For example, anaerobic digestion is used to reduce sludge disposal volume to at best 50%. The process generates low BTU biogas releasing methane and CO.sub.2 greenhouse gases, if not captured. Presently 600 wastewater treatment plants in the US flare off this biogas directly to atmosphere, losing any fuel benefit and compounding greenhouse gas emissions. More importantly, this process still requires landfilling of the balance of the sludge resulting in a large footprint as biological processes are slow to degrade these remaining sludges.

[0066] Land application decomposition produces CO.sub.2, H.sub.2S, SOx, NOx, CH.sub.4 and H.sub.2O greenhouse gas emissions. It also requires solids drying to reduce the disposal volume and has a long decomposition time in years, continually emitting greenhouse gases to atmosphere, while generating odors.

[0067] FIG. 3 illustrates how suspended solid substrates adsorb PFAS, PPCPs, pathogens, heavy metals, which are released when the substrate is broken down by microbes. Their upfront removal significantly improves reclaimed water quality and reduces loading on a wastewater treatment plant's bioremediation equipment; thereby expanding its processing capacity. Gasification/Combustion of the separated solids then destroys the sorbed PFAS, PPCPs, prions, pathogens. Heavy metals separately acid washed from the solids substrate are chemically precipitated via lime addition to precipitate metal hydroxides for independent disposal.

[0068] FIG. 4 illustrates salt balancing with bi-valent ions to repeal and leach away from the roots monovalent saline salts, retaining needed plant nutrients.

[0069] FIG. 5 illustrates the fuel value of anaerobically digested sludge vs. separated primary solids. Separated primary solids have 25% more fuel value than anaerobically digested sludge as the anaerobic microorganisms first consume the high energy volatiles to produce biogas. Thus the fuel value of primary separated solids is approximately 9,000 BTU/lb. compared to waste activated separated sludge having a BTU value of approximately 6,500 BTU/lb.

[0070] FIG. 6 illustrates acid cation agglomeration of colloidal bio solids without polymers. Suspended solids are negatively charged, and when hydrogen cation acid is added, they readily coagulate for easy separation. As the acid addition avoids hydrophilic polymers, the sulfurous acid chemically dried bio solids contain less than 10% water vs. 40% water of polymer separated solids.

[0071] FIG. 7 illustrates separated bio solids drying energy usage for polymer separated sludges vs. chemically dried separated solids. For gasification or combustion, the separated bio solids must be dried to less than 20% water content before power generation. This requires large drying energy usage of polymer separated solids, which constitutes approximately 60% of the fuel value according to “Techno-Economic Analysis of Wastewater Biosolids Gasification” by Nick Lumley et al; ww3.aiche.org/ . . . ?p325428.page 7, supra. Chemically dried separated solids thus generate significantly more fuel value than dried polymer separated fuels.

[0072] FIG. 8 illustrates an example of a flow diagram removing upfront suspended organic solids for chemical drying, and conditioning the filtrate as reclaimed water for land or stream application without bioremediation processing. Sulfurous acid at a pH less than 6.5 is added via a sulfurous acid generator to saline wastewater influent with PPCPs, PFAS, colloids, heavy metals, phosphates, nitrates, carbonates, silicates, to precipitate and remove the suspended solids with sorbed PFAS/PPCPs/Prions/Pathogens, which are dried using a drain Pad/Dryer, belt press, etc. for chemical drying without heat. After 24 to 48 hours, the chemically dried solids have less than 10% water and are transferred to a gasifier or combustor, such as a kiln, co-fired boiler, etc. This destroys sorbed PFAS/PPCPs/Prions/Pathogens, while generating more power output with reduced greenhouse gases, as methane and nitrous oxide anaerobic production are avoided.

[0073] The filtrate is then lime adjusted in a dwell tank at a pH greater than or equal to 9 for precipitating metal hydroxides, calcium phosphates, calcium sulfites, calcium silicates, and calcium carbonates for separation with a filter or settling tank. At pH 9, this second filtrate is high in nitrates and sulfites and may contain some dissolved PFAS. The second filtrate is exposed to UV 315 nm or below, preferably between 250 and 270 nm, exciting the sulfites to reduce nitrates to nitrogen gas and destroying PFAS leaving a treated reclaimed wastewater which is disinfected, metal free, salt balanced, and has reduced PFAS/PPCPs/Prions/Pathogens and negligible N and P.

[0074] This chemical treatment without biological reduction significantly reduces BOD, nitrogen, phosphates, heavy metals, pathogens and other contaminants. It also provides a renewable biofuel for gasification or co-firing with other fuels to destroy sorbed PFAS/PPCPs/Prions and reduce overall greenhouse gas production.

[0075] The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.