Improved system used for contaminant control in wastewater

Abstract

A system used for contaminant control has a container with a mixing well portion and a settling tank portion. Wastewater entering the system is conveyed from a water inlet into the mixing well portion, where sediment or contaminants can be removed from the wastewater. The wastewater is moved to a settling tank portion, where additional sediment or contaminants are removed by settling to the bottom of the tank. A weir positioned at a top surface of the settling tank portion removes clarified water from the system. The settled sediment or contaminants can be removed from a sludge piping system. A flocculant additive system and lamella separators can also be used to assist settling processes. Further, a recirculation system can be used to reintroduce settled contaminants into the mixing well portion to increase efficiency of the system.

Description

TITLEIMPROVED SYSTEM USED FOR CONTAMINANT CONTROL IN WASTEWATERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 63 / 699,248, filed on September 26, 2024, which is incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

[0002] Not applicable.BACKGROUND OF THE INVENTION

[0003] The present disclosure generally relates to a system for sediment control in wastewater. More specifically, the disclosure relates to a portable settling tank that can be used to remove sediment, pollutants, and other aqueous contaminants from wastewater.

[0004] Managing sediment and pollutants in water can be a costly and resource-intensive process. State and federal rules in the United States, such as the Clean Water Act, regulate the discharge of sediment and other contaminants into public waterways. To comply with these regulations, entities operating in industries such as construction and manufacturing employ various techniques to capture and treat on-site water before it enters public waterways. In many instances, the water is rain and snowmelt that gathers sediment and contaminants present at the construction site or manufacturing facility. For example, the construction industry will build retention ponds to capture surface runoff that becomes loaded with soil and debris. The retention pond allows the sediment to naturally settle out of the water before draining to a natural waterway. While effective, retention ponds require a large area on the construction site and the retained water must dwell in the pond for a significant period of time. The manufacturing industry may employ water treatment facilities, similar to a sewage treatment plant, which can add significant operational costs to the manufacturing facility. Like retention ponds, these treatment facilities are constructed in a fixed location and are used to remove dust and other manufacturing byproducts contaminating onsite water.

[0005] To permit a more flexible approach to water treatment demands, mobile sediment tanks and treatment stations have been employed. These mobile units are particularly useful in the construction industry, where projects may have a duration of only several months, making the development of a permanent retention pond less than ideal. Some of these mobileunits utilize flocculation, where the settling time is reduced through the use of the chemical flocculant. Despite the improvements over sediment ponds or fixed treatment facilities, these units often suffer from low flowrates, incomplete flocculation, and sludge accumulation. In some situations, the sludge must be further processed in a separate treatment facility or the treatment process has to be stopped to allow sludge removal from the settling tank.

[0006] Therefore, it would be advantageous to develop a sediment control system that provides sufficient sediment and contaminant removal while providing improved contaminant removal, including improved flocculation and sludge control.BRIEF SUMMARY

[0007] According to embodiments of the present disclosure is a system suitable for use in sediment control and contaminant removal from wastewater. The system comprises a container having a mixing well portion and a settling tank portion. A flocculant additive area allows chemical flocculants or other additives to be added to the incoming wastewater stream. Lamella separators in one or both of the mixing well portion and the settling tank portion assist in the removal of sediment and other contaminants from the wastewater stream. Sludge, which settles to the bottom of the settling tank portion, is removed from wastewater though piping disposed on the bottom of the wells. Recirculation piping can help control the consistency of the sludge exiting the system. The container can be constructed on the frame of a roll-off container, making the system portable and easily transportable.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0008] Figs. 1 A-1B are left side and topviews of the system, according to one embodiment.

[0009] Fig. 2 is an end view of the system.

[0010] Fig. 3 is a right side view of the system.

[0011] Fig. 4 is an end view of the system.

[0012] Fig. 5A is a top view of the system.

[0013] Fig. 5B is a detailed view of the mixing tank portion.

[0014] Fig. 6 is an isolated view of the various piping of the system.

[0015] Fig. 7A is a close-up view of a venturi injector and associated piping.

[0016] Fig. 7B shows a venturi injector with diverter valves in the turbulation piping.

[0017] Figs. 8A-8B show an alternative embodiment with a dissolved air flotation system.

[0018] Fig. 9 shows a cross-sectional view of the system.DETAILED DESCRIPTION

[0019] According to embodiments of the disclosure is a system 100 that can be used for sediment control. As shown in Figs. 1A-1B, the system comprises a container 101 having a settling tank portion 102 and a mixing tank portion 103, providing a two-stage separation process. Fig. IB provides an overhead view of the container 101, with the mixing tank portion 103 shown adjacent to the settling tank portion 102. In the embodiment shown in Figs. 1A- 1B, the container 101 is built on the platform of a typical roll-off container, allowing easy transport of the system 100 using a truck adapted to haul dumpsters and similar containers. Fork pockets are also shown in Fig. 1A, acting as additional lifting means 105 and highlight the portable nature of the system 100, which contains all necessary components within the footprint of the container 101. In an alternative embodiment, the settling tank portion 102 and mixing tank portion 103 may be housed in separate containers 101. For example, each can be implemented in separate roll-off containers 101. Further, the system 100 can be daisy-chained to remove additional contaminants from the supernatant.

[0020] On sites where water is to be treated, wastewater is pumped or diverted into the system 100, entering through a water inlet 110, near the bottom of the container 101. Fig. 2 shows the water inlet 110 at the end wall of the container 101. The water inlet 110 may include a plumbing tee 111 (shown in Fig. 6), which allows rocks and heavier debris to drop from the water stream as the water moves up vertical inlet pipe 112. The top of inlet pipe 112 includes an access hatch 114. A cleanout 113 may be provided at the bottom of water inlet 110, tee 111, or pipe 112 to allow removal of accumulated debris. The water inlet 110 may further include a valve to control the flowrate of the wastewater stream entering the system 100. In some embodiments, the removal of sediment depends, in part, on the flow rate of water through the system and the valve helps control the sediment removal rate and level of sediment remaining in the effluent. The water inlet 110 may optionally include a second water input, which can be connected to a pump, to allow staged input.

[0021] The end wall of the contain 101 further houses a flocculant additive area 120. To assist settling of contaminants in the system 100, a flocculant may be added to the incoming wastewater. Flocculants adhere to solids suspended in the water, which aggregate into flocs. Flocculants, such as polyacrylamide, carboxymethyl cellulose, and polyanionic cellulose, and others known in the art, can be used. Other additives or chemicals can be added from the additive area 120. For example, chemicals can be added that cause contaminants held in solution to precipitate out of the wastewater. In one embodiment, the flocculant is stored in powder form in the flocculant additive area 120. The powder is added to the incomingwastewater stream as a powder, a concentrated liquid, or a semi-hydrated powder. For the semi-hydrated powder, which is often in the form of a gel disposed on a retainer, the flocculant can be placed inside the access hatch 114. Incoming wastewater will slowly scavenge flocculant as it passes over the surface of the gel. This can be a low-cost option for introducing flocculant. In an alternative embodiment, the flocculant may be added directly to the mixing well portion 103. Optionally, a dual diaphragm pump, peristaltic pump, or other type of pump introduces the flocculant in a multi-staged injection process.

[0022] Once the wastewater enters the inlet 110 and the flocculant is injected, the water / flocculant mixture enters a turbulation area 130. As shown in Fig. 1A, the turbulation area 130 comprises piping 131 extending from the water inlet 110 and moving through a series of elbows 132 or 90 degree bends. The bends 132 serve two purposes — extending the length of the turbulation piping 131 by winding the piping 131 back-and-forth within the volume of the turbulation area 130 (rather than traveling in the shortest path) and introducing turbulence into the flow of water within the piping 131 as a result of the direction changes. In addition to elbows 132, static mixers can also be used to enhance mixing of the water and flocculant (or other additives). With a longer length of piping 131, multiple injection points for the flocculant into the water stream can be used. In the embodiment shown in Fig. 1 A, the length of piping 131 is roughly 54 feet, despite the width of the container 101 housing the turbulation area 130 being only a few feet wide. The piping 131 may include a slope to allow water to drain by gravity, preventing water from freezing in the piping 131 during storage in cold environments. The turbulation piping 131 terminates at mixing well inlet 136, as shown in Fig. 6.

[0023] Further shown in the turbulation area 130 is a venturi injector 133. Fig. 7A shows a detailed view of the venturi injector 133 integrated with the turbulation piping 131. The venturi injector 133 is used to recirculate flocs from the settling area 102 through the settling area drain 147, the settling output 145, or the sludge piping 146 to allow for continual operation once the settling area begins to fill with sediment and to control the consistency of the sludge exiting the system 100. The venturi injector 133 creates a pressure gradient as the wastewater passes through the piping 131, resulting in effluent from the settling tank portion 102 to be drawn into the piping 131. Recirculation may be accomplished with a pump or other device rather than a venturi injector 133. One advantage of the venturi injector 133 is that electrical power is not needed. In one embodiment, the turbulation piping includes diverter valves 139 that allows the flowpath of the water in the turbulation piping 131 to bypass the venturi injector 133. The bypass circuit can be used when the consistency of the effluent is in a desired range and recirculation is not wanted. Fig. 7B shows the embodiment with the diverter valves 139.

[0024] The recirculation system, or venturi injector 133, can also be used to improve the performance of the system 100 by allowing increased removal of contaminants or sediment from the mixing well portion 103. By way of further detail, heavier particles settle more easily in the mixing well portion 103 than lighter particles given the smaller area of lamella separators 140 and / or turbulence of the water in this portion 103 of the container 101. In some scenarios, the wastewater streams may have such light particles that they do not easily settle in either the mixing tank portion 103 or the settling tank portion 102. By reintroducing settled or flocculated particles from the bottom of the mixing tank portion 103 into the mixing well portion 103, these previously settled particles can combine with incoming particles and settle in the mixing tank portion 103. This leaves more capacity in the settling tank portion 102, increasing the overall performance and efficiency of the system. In addition, the amount of flocculant or additive introduced into the system can be reduced as a result of the recirculation. In this manner, the mixing well portion 103 and settling tank portion 102 work in tandem as a two- stage settling process.

[0025] For example, the mixing well portion 103 may settle 40% of the solids whereas the settling tank portion settles the remaining 60%. If the mixing well portion 103 was not capable of settling lighter particles due to recirculation and only settled 20%, the size of the settling tank portion 103 would have to be increased to deliver similar performance. Even with an increased size, some conventional systems are incapable of settling lighter particles. In an embodiment where the wastewater flowrate into the system 100 is 500 gallons per minute, the recirculation venturi 133 may reintroduce 40 gallons per minute of effluent from the settling tank portion 102. In one embodiment, the recirculation flowrate is 3-10% of the incoming flowrate. However, this range may vary depending on the makeup of contaminants in the incoming wastewater. The wastewater pulled from the settling tank portion 102 contains fine particles and the effluent may be watery. By recirculating the fine particles in this effluent into the mixing tank portion 103, it can be mixed with additional flocculant or other additives. As discussed above, by recirculating the effluent from the settling tank portion 102, the total amount of sediment or contaminants removed from the wastewater stream entering the system 100 can be increased compared to other systems. For example, if the input to the system is 500 gallons per minute, the effluent from the sludge outlet 145 may be 50 gallons per minute or less, with the composition of the effluent being 40-50% solid particles. Some of this effluent can be recirculated into the mixing tank portion 103. The remaining 450 gallons per minute will be output as clarified water through the outlet piping 151, which is shown in Fig. 4. In contrast, prior systems may output over 100 gallons per minute as sediment effluent, with onlya 10% solid particle composition. Such a low rate of sediment removal in these prior systems would require additional treatment of the sludge.

[0026] In the configuration shown in Fig. 1A, the venturi injector 133 removes concentrated flocculated particles at the bottom of the settling chamber 102, assisted by the hydrostatic pressure from the water column above the outlet 145 of the settling tank portion 102. The venturi injector 133 is positioned inline with the turbulation piping 131, such that water flowing through the piping 131 will cause a pressure differential in venturi piping 134, which is connected to the outlet 145 of the settling tank portion 102 via the sludge piping 146. The venturi injector 133 may include a pressure relief valve if the flowrate of water into the piping 131 exceeds a threshold of the injector 133. By using the venturi injector 133, in combination with a venturi valve 135, the consistency of the sludge and clarified water exiting the system 100 can be adjusted. For example, if too many fine particles remain in the clarified water exiting the system, the venturi valve 135 can be opened to recirculate a portion of the wastewater into the mixing tank portion 103.

[0027] Once the water stream exits the turbulation area 130, it enters the mixing tank portion, or mixing well, 103 of the container 101. The mixing well 103 is shown behind the turbulation piping 131 in Fig. 1A. In Fig. 5A, the mixing well 103 is shown adjacent to the turbulation area 130, near the end wall of the container. In the embodiment shown in the Figs. 1 A-1B, the mixing well 103 has a volume of about 1,100 gallons. However, the volume of the well 103 may vary depending on the intended flowrate of water through the system 100, the loading of sediment in the wastewater, or the overall capacity of the system 100. The purpose of the mixing well 103 is to allow maturation of the flocculant particles, settle out large flocs, and to act as a decanter to help control the consistency of the sludge output. For example, heavier debris in the wastewater stream will typically settle out in the mixing well portion 103, being removed through the mixing well outlet 137, as shown in Fig. 6. A pump can be provided to assist with the removal of solids from the bottom of the mixing well 103. Further shown in Fig. 5A are lamella separators 140, which assist with the settling of solids. Water enters below the lamella separators 140, with solid particles settling on the surface of the lamella 140 and falling to the bottom of the well 103 and partially clarified water rising above the lamella 140.

[0028] The large surface area of the water in the mixing well 103 can allow for the use of oil booms to collect oils that float on the surface of the water. Fig. 5B shows a close-up view of the mixing well portion 103 without the lamella separators 140 visible, permitting a view of input diffusion piping 141, which introduces the water into the mixing well portion 103 in a more controlled manner, preventing agitation of settled debris in the mixing well 103. Alsoshown in Fig. 5B is an air release valve 143 that can be used to remove air accumulated in the turbulation piping 131.

[0029] The mixing well portion 103 can also act as a decanter, allowing floating debris to be removed from the wastewater stream. To ensure the floating debris is not sent to the settling tank portion 102, a partition or baffle 142 may be provided between the two sections 102 / 103 of the container 101. A perimeter wall of the partition 142 will typically have a height extending above the surface of the water in the mixing well portion 103. A flow-path down a first section of the partition 142 that is contained in the mixing well portion 103, then up a second section of the partition that is contained in the settling tank portion 102 allows a controlled transfer of wastewater without passing the floating debris. In embodiments where the mixing well portion 103 is housed in a separate container 101 from the settling tank portion 102, the partition 142 may not be present. Instead, piping can be used to transfer the water from one tank to the other.

[0030] Water exiting the mixing well portion 103 will move to the settling tank portion 102 via the overflow area (i.e. partition or baffle 142) separating the two portions 102 / 103. The settling tank portion 102 may also include lamella separators 140, which can be provided in a variety of forms known in the art, including angled tubes or plates. The partition 142 further permits wastewater entering the settling tank portion 102 to enter below the level of the lamella 140. In this manner, water begins to rise through the lamella separators 140, while solid particles and / or flocs settle and sink to the bottom of the settling tank 102.

[0031] The flocculated particles settling on the lamella separator 140 move towards sludge outputs 145 at the bottom of the settling tank portion 102. As the particles collect at the bottom of the well 102 near the outputs 145, they begin to form a concentrated, thick substance referred to as ‘sludge’. In the embodiment shown in Fig. 1A and 1C, the sludge outputs 145 are disposed at the bottom of angled, cone- or pyramid-shaped collectors at the bottom of the well 102. Fig. 3 shows the opposite side of well 102, with the shape of the collectors visible. Further, the sludge outputs 145 are connected to sludge piping 146, which may be connected to a pump or other device to remove the sludge. In one embodiment, the sludge piping 146 is connected to the water inlet 110 via a valve, which permits the sludge piping 146 to be backwashed with incoming wastewater. When activated, the flow of water is reversed and the wastewater enters the bottom of the settling tank portion 102 via the sludge piping 146. This process can be performed periodically to remove obstructions or to clear material from the system 100. Fig. 9 is a cross-sectional view of the system 100 and shows areas below thelamella separators 140 where sludge can accumulate at the bottom of the settling tank portion 102.

[0032] In one embodiment, the lamella separator 140 has a height of 41 inches and covers the entire horizontal plane of the settling tank portion 102. However, the lamella 140 separator may have a range from several inches to the full height of the container 101.

[0033] With the sediment and other particles removed from the bottom of the settling tank portion 102, the clear water remains at the top of the well 102. This water can be collected for further treatment or discharged on-site, depending on the requirements of the site and the initial and / or final contamination load in the wastewater. To collect the clarified water at the top of the settling tank 102, a weir 150 is positioned near the surface of the water level in the settling tank portion 102 of the container 101. The weir 150 extends from near the end-wall of the container 101 towards the middle of the settling tank portion 102. The orientation of the weir 150 permits out-of-level operation as water will be able to flow into the weir 150 even when the surface of the water is not parallel with the top plane of the weir 150. For example, in one embodiment, the weir 150 permits out-of-level operation up to 9 inches front to back and 6 inches side to side. Out-of-level operation will occur as long as some portion of the weir’s border is below the surface of the water. The inlet weir 150 is configured to disperse any concentrated flows to improve performance of the lamella separator 140. That is, water will enter the weir 150 around the full perimeter of the weir 150, preventing one-side or an isolated section of the weir 150 to collect more water than other sections. If this occurs, it could create a higher flowrate of water through the lamella 140, preventing the solids / flocs from settling as they get carried up through the lamella 140 by the faster moving water.

[0034] As water enters the weir 150, it is directed through outlet piping 151 to exit the system 100. The outlet piping 151 may discharge water through gravity or with a pump. In one embodiment, the outlet piping 151 is positioned up to 24 inches above ground to allow pump connection. Alternatively, a gravity discharge is operational up to 6.5 feet above ground level.

[0035] In one embodiment of the system 100, a dissolved air flotation system 160 is provided to assist with the removal of oils and other debris. Figs. 8A-8B show the dissolved air flotation system 160, which scrappers 161, installed above the mixing tank portion 103. In this type of system 160, air is dissolved in the wastewater stream, typically under pressure, and released in the form of bubbles in the settling tank portion 102 or mixing well portion 103. The bubbles adhere to oils and other debris, which can then be skimmed from the surface of the water. Skimming can be performed using mechanical scrapers 161. As shown in Figs. 8A-8B,the scrappers 161 are bars positioned at the surface of the mixing well portion 103, spanning from one side to the other. The scrappers 161 are driven by an electric motor connected to the scrappers 161 by a chain or belt. When actuated, the scrappers 161 will skim material on the surface of the water in the mixing well 103 to be deposited in an adjacent container 163. In one alternative embodiment, scrappers 161 are provided in both the mixing well portion 103 and the settling tank portion 102.

[0036] Optional features of the system 100 may include a power source such as a battery, solar panel, or water turbine. Other optional features include means for moving the container 101, such as forklift pockets, a roll-off frame, and lift points. Finally, valving can be used to connect the different outlets. For example, the sludge piping 146 can be connected to the outlet of the dissolved air flotation system 160, leading to a single output.

[0037] When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps, or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

[0038] The invention may also broadly consist in the parts, elements, steps, examples and / or features referred to or indicated in the specification individually or collectively in any and all combinations of two or more said parts, elements, steps, examples and / or features. In particular, one or more features in any of the embodiments described herein may be combined with one or more features from any other embodiment s) described herein.

[0039] Protection may be sought for any features disclosed in any one or more published documents referenced herein in combination with the present disclosure. Although certain example embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims are to be construed literally, purposively, and / or to encompass equivalents.

Claims

CLAIMSWhat is claimed is:

1. A system used for water treatment comprising: a container having a mixing well portion and a settling tank portion; a water inlet comprising a turbulation pipe, wherein the water inlet conveys wastewater having suspended contaminants into the mixing well portion, wherein a first portion of the contaminants settles from the wastewater in the mixing well portion; a sludge outlet positioned at a bottom of the settling tank portion for removing concentrated wastewater containing a second portion of the contaminants; a weir positioned near a top of the settling tank portion for removing wastewater having devoid of the contaminants from the container; and a connection between the settling tank portion and the water inlet for recirculating a fraction of the second portion of contaminants from the settling tank portion to the mixing well portion.

2. The system of claim 1, further comprising: a flocculation additive system adapted to inject a powdered flocculant into the wastewater prior to the wastewater entering the mixing well portion.

3. The system of claim 1, further comprising an additive system configured to introduce an additive to the wastewater prior to entering the mixing well portion.

4. The system of claim 1, further comprising: a venturi disposed inline with the turbulation piping and configured to create a pressure differential in the connection, causing the fraction of the second portion of contaminants from the settling tank portion to be drawn into the turbulation piping.

5. The system of claim 1, wherein the turbulation piping is disposed in the container outside of the mixing well portion and the settling tank portion.

6. The system of claim 1, further comprising:a dissolved air flotation system disposed in the mixing well portion.

7. The system of claim 1, further comprising: a lamella separator disposed in at least one of the mixing well portion and the settling tank portion.

8. The system of claim 4, further comprising: a diverter valve to isolate the venturi from the tubulation piping.

9. The system of claim 1, further comprising: a water outlet connected to the weir.

10. The system of claim 9, wherein the water outlet is positioned at a height above the bottom of the container.

11. The system of claim 1, wherein a flow path of the wastewater comprises a path from the water inlet through the turbulation piping into the mixing well, through a diverter wall separating the mixing well portion and the settling tank portion, into a settling tank portion, through lamella in the settling tank portion, into the weir, and an outlet connected to the weir.

12. The system of claim 1, wherein the turbulation piping further comprises: a length of pipe having a plurality of direction changes.

13. The system of claim 1, wherein system is contained within a footprint of the container.

14. The system of claim 13, wherein the container is configured to be transported by a vehicle capable of moving a roll-off container.

15. The system of claim 1, wherein the water inlet further comprises a static mixer.

16. A method of treating wastewater having contaminants comprising:conveying wastewater through a water inlet; mixing the wastewater with an additive using a length of pipe having a plurality of direction changes, wherein the length of pipe is connected to the water inlet; filling a mixing well, wherein the mixing well allows a first portion of contaminants contained in the wastewater to settle to a bottom of the mixing well; transferring the wastewater from the mixing well to a settling tank, wherein the settling tank contains a lamella separator; collecting a second portion of the contaminants at a bottom of the settling tank portion; removing a supernatant from a top portion of the settling tank, wherein the top portion is separated from the bottom portion by the lamella separator; and recirculating a fraction of the second portion of the contaminants back into the length of piping for reintroduction into the mixing well with additional wastewater.

17. The method of claim 16, wherein recirculating the fraction of the second portion of the contaminants is performed without a pump.

18. The method of claim 17, wherein a flowrate of the contaminants recirculated into the length of pipe is 3-10% of a flowrate of the wastewater conveyed through the water inlet.

19. The method of claim 16, wherein recirculating the fraction of the second portion of the contaminants is performed using a venturi connected to the length of pipe.

20. The method of claim 16, wherein the mixing well contains an additional lamella separator.

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