PASSIVE SAMPLER DEPLOYMENT HOUSING

Abstract

A passive sampler deployment housing, the housing comprising a channel for guiding a stream flow of a liquid in a main direction, the channel having two side walls and one downstream wall, defining a sampling chamber; at least one support means adapted for supporting at least one detecting means and arranged in the channel, the downstream wall, disposed essentially perpendicular to the liquid main direction, having a height such that the flow of the liquid is accumulated in the channel at a level that is sufficient to overlap the support means and optionally the detecting means. The invention also relates to a device including the housing of and at least one detecting means, the at least one detecting means comprising a frame including two membrane supporting means, and a membrane, comprising a sorbing material, which is clamped therebetween.

Claims

1-17. (canceled)

18. A passive sampler deployment housing, said housing comprising: a channel for guiding a stream flow of a liquid in a main direction, the channel having two side walls and one downstream wall, defining a sampling chamber; and at least one support means adapted for supporting at least one detecting means and arranged in the channel, the downstream wall, disposed essentially perpendicular to the liquid main direction, having a height such that the flow of the liquid is accumulated in the channel at a level that is sufficient to overlap the at least one support means and optionally the at least one detecting means.

19. The housing according to claim 18, including an inlet, disposed upstream of the channel, the housing comprising a mesh screen delimiting an upper end and a lower end having a V-shaped form, presenting two angular walls, the angle between the two walls is of from 45° to 80°, having a ∩ shape or an arc of circle shape.

20. The housing according to claim 19, wherein the inlet includes an upstream wall disposed at an upstream position with regard to the at least one support means, the upstream wall is perpendicular to both side walls of the channel.

21. The housing according to claim 18, including a cover removable from the housing, comprising a strip fixed to the cover and protruding downwards to the cover, the strip being parallel to the upstream wall.

22. The housing according to claim 21, wherein the strip is disposed downstream to the upstream wall.

23. The housing according to claim 21, wherein the cover has a shape fitting the combination of the inlet, the sampling chamber and an outlet area comprising the downstream wall set downstream to the sampling chamber, with two bended walls going downwards that cover the external side of the respective side walls of the sampling chamber.

24. The housing according to claim 21, wherein the downward end of the strip is located lower than the upper end of the upstream wall.

25. The housing according to claim 21, comprising a grid fixed to the cover and protruding downwards to the cover, the grid being parallel to the strip.

26. The housing according to claim 21, wherein the at least one support means comprises an upper part and a lower part, the lower part being fixed on a bottom wall of the channel, and the at least one support means is extending radially.

27. The housing according to claim 21, wherein the at least one supporting means is provided with a corresponding at least one detecting means elevating means, that allow the at least one detecting means to be at a predetermined distance from the bottom wall of the channel.

28. The housing according to claim 27, wherein the at least one detecting means elevating means is fixed at any portion of the length of the at least one supporting means in contact with the bottom wall (21).

29. The housing according to claim 28, wherein the at least one detecting means elevating means is fixed at the area defined by the lower part of the at least one support means.

30. The housing according to claim 21, the housing being provided on each side walls with at least one fixation means fixed below the bottom of the side walls.

31. The housing according to claim 21, wherein the channel includes at least one cover fixation means, fixed onto the bottom wall of the sampling chambe, adapted to cooperate with at least one corresponding hole of the cover.

32. A device including the housing of claim 21 and at least one detecting means, the at least one detecting means comprising a frame including two membrane supporting means, and a membrane, comprising a sorbing material, which is clamped therebetween.

33. The device according to claim 32, wherein the frame comprises a least two fixation means adapted to make the two membrane supporting means clamped each to the other for supporting the membrane.

34. The device according to claim 32, wherein the at least one detecting means is fixed at a predetermined distance from the bottom wall by at least one supporting means, cooperating with at least one corresponding hole arranged in the frame, and at least one corresponding elevating means, and the at least one detecting means is essentially parallel to the bottom wall.

35. The device according to claim 32, comprising at least two detecting means separated one from the other by a predetermined distance (d) in the main direction.

Description

DRAWINGS

[0046] FIG. 1 is a perspective view of the open version (without the hard cover) of the housing according to various embodiments of the invention.

[0047] FIG. 2 is a perspective view of the up-side-down hard cover according to various embodiments of the invention.

[0048] FIG. 3 is a lateral view of the closed housing according to various embodiments of the invention.

[0049] FIG. 4 is a top view of the device including detecting means according to various embodiments of the invention.

[0050] FIG. 5 is a top view of the housing with various screen mesh according to some exemplary embodiments of the invention, with various number of detecting means and with various configurations of supporting means.

[0051] FIG. 6 is a rear view of the housing according to various embodiments of the invention.

[0052] FIG. 7 is a histogram of the recoveries of several organic contaminants obtained with the presented embodiment and with a commercially available deployment housing.

[0053] FIG. 8 is a histogram of the relative standard deviation of several organic contaminants obtained with the presented embodiment and with a commercially available deployment housing.

DETAILED DESCRIPTION

[0054] The invention provides a solution when dealing with detecting means or passive samplers exposed in shallow sampling environment and/or having a high turbidity. The invention can also be used in a more classical way, for example in a liquid with a low turbidity and/or during a high flow period.

[0055] For example, the housing, and especially the device, can easily be handled for example in a river or in any water environment. The liquid is feeding the sampling chamber where the passive samplers are hosted and where they can stay immersed during low flow or dry periods. The inlet combines a mesh screen and a finer particle retention system including an upstream wall to protect the passive samplers from clogging by smaller foreign materials. The housing includes a removable cover to protect the passive samplers when present from any damages and fixation means to fix the housing or the device either in the sampling environment bed or on a support provided with a quick release system to ease the removal and the installation of the support or the device. The outlet area includes a downstream wall with a raised opening in the sampling chamber to retain a volume of liquid enough to keep the passive samplers, when present, immersed during dry or low flow periods and to let the liquid flow outside during higher flow. In practice, passive samplers are mounted in the sampling chamber parallel to its bottom and secured in position. The hard cover is then closed and secured. The device is placed in the sampling environment with the inlet pointing towards the upstream of the liquid flow and secured by its fixation means or by its support.

[0056] When working during a dry or low flow period, the sampling of the liquid will only start when its level will reach the top end of the upstream wall. The liquid will then fill the sampling chamber and the passive samplers will start the collection of the contaminants/pollutants. The liquid leaves the sampling chamber when it reaches the top of the downstream wall of the outlet area. When the level of the liquid in the sampling environment is decreasing and gets below the top of the upstream wall, the sampling chamber is no longer fed and the liquid inside is trapped.

[0057] Information about the collections of contaminants by the passive samplers is completed by a series of probes installed inside the chamber allowing the record of the water level in the chamber. The probes are controlled by a PCB located in a hermetic box on top of the housing or of the device and data are stored on a memory flash. PCB and probes are powered by batteries.

[0058] When working during the wet season or high flow periods, the presented embodiment is always fully immersed and acts directly like the commercially available deployment housings.

[0059] When the deployment time is over, either the passive samplers can be replaced by new ones or the whole housing can be removed from the site.

[0060] The housing exemplarily depicted in FIG. 1 is made of a material based on stainless steel or based on any other nature, such as glass, polymer, and ceramics. The housing includes a channel for guiding a stream flow of a liquid in a main direction an inlet 14 towards an outlet area 13. A removable mesh screen 3 and a finer particle retention system is arranged at the inlet 14, as well as an upstream wall 5. The outlet area 13 comprises an outlet wall 8 and the housing comprises a sampling chamber 7 delimited by the upstream wall 5 and the outlet wall 8, as well as by two side walls 17, 18. The sampling chamber 7 is very in various instances liquid tight to avoid any liquid loss.

[0061] The housing further comprises support means 2 arranged in the sampling chamber 7 and adapted for supporting detecting means (not shown).

[0062] Cover fixation means 1 allow the additional mounting of an optional cover (see 15 on FIG. 2) and extend upwards from a bottom wall 21. Cover fixation means 1 can comprise one means located at the upstream of the inlet means 14 and another means at the middle of the sampling chamber 7. Some additional cover fixation means 1 can be provided, for example one or two more.

[0063] The removable mesh screen 3 comprises an upper end 3a and a lower end 3b and has a V-shaped form presenting two angular walls 19, 20, the angle between the two angular walls 19, 20 being of between about 30° and 70°, in various instances 45° to 60°. Alternatively, the screen mesh 3 can have a ∩ shape (FIG. 5). The screen mesh 3 prevents larger foreign materials from entering in the sampling chamber 7. These shapes allow the larger foreign materials to slide along the removable mesh screen 3 avoiding the clogging of the inlet 14 thereof. Its removable ability is firstly made to exchange the mesh screen 3 and adapt the mesh size according to sampling environment and secondly for maintenance reasons described later. The mesh size is about 5 × 5 mm, in various instances 2 × 2 mm, and the mesh can be of square of circular shape or any other shape that allows the retention of large undesirable materials. The mesh can be disposed perpendicularly to the angular walls 19, 20 or perpendicularly to the plane defined by the upstream wall 5.

[0064] As shown in FIG. 1, each cover fixation means 1 is a threaded rod pointing upwards, length thereof being higher than the side walls 17, 18 heights, adapted to guide and secure the hard cover 15 with wing nuts (not shown). The cover fixation means 1 are here located at the middle of the bottom wall 21 between two sets of two support means 2 and at the front part behind the mesh screen 3.

[0065] The housing is provided on each side wall 17, 18 with two fixation means 9 which are here two anchorage points (FIG. 4). Each anchorage point 9 consists of a perforated stainless-steel plate fixed below the bottom of the side walls 17, 18. With these four anchorage points 9, the housing can be secured to the sampling environment bed by inserting any kind of spike with a curved end.

[0066] A quick release system can ease the removal and the installation of the housing. Alternatively, the anchoring of the housing can be made through a separated part and can consist of a perforated stainless-steel plate with four slides on top (not shown) that allow the hosting of the anchorage points 9 of the housing. The slides are built in a way that the housing cannot slip out backward. The quick release support can have a stainless toggle latch that secures the housing in position. Slides and toggle latch are place in a way that the presented embodiment fits properly in (not shown).

[0067] A finer particles sediment trap 10 is confined by the angular walls 19, 20, the bottom wall 21 and the upstream wall 5.

[0068] The upper end 3a of the mesh screen 3 presents a height that is greater than the height of the upstream wall 5 depicted by the upper end 5a (FIG. 1). Such a disposition enhances the retention of water in the sampling chamber 7 and enhances the retention of particles having dimension smaller than those retained by the mesh screen 3.

[0069] The combination of the mesh screen 3 and the finer particle retention system 10 is acting as a flow buffering system.

[0070] The housing includes the sampling chamber 7 which is here a seal tub, delimited by the two side walls 17, 18 and a bottom wall 21 extending from the inlet 14 to the outlet area 13.

[0071] The sampling chamber 7 comprises four support means 2, here being threaded rods, each comprising an upper part 2a and a lower part 2b, the lower part 2b being fixed on a bottom wall 21 of the channel, and each support means 2 is extending radially (FIG. 3). Depending on the configuration of the housing, two supporting means 2 define a set for holding the detecting means 23, 24. The distance between each support means 2 in the same set is of from 5 cm to 15 cm.

[0072] The shape of the cover 15 is designed to fit the shape of the assembly of the mesh 3 and the walls 5, 8, 17, 18 and has a spearhead shape (FIG. 2). The cover 15 has along the longer sides, two bended walls 15a, 15b going downwards in order to avoid lateral movement of the cover 15 when installed. The two through holes 12 are designed to host the two threaded rods 1. The two bended walls 15a, 15b help to close and seal the housing. The cover 15 is secured by two wing nuts (not shown) screwed at each threaded rod 1. On the inner side of the cover 15, is the strip 11 of the finer particle retention system. The strip 11 is located backwards than the upstream wall 5 in order to let the liquid from of the sampling environment flows between them. The downward end 11b of the strip 11 is located lower than the upper end 5a of the upstream wall 5 (FIG. 3). The grid 31 is located at the outlet area above the downstream wall 8.

[0073] The function of the strip 11 is to block the floating materials that would have passed above the upper end 5a of the upstream wall 5. Another function of the strip 11 is to reroute the liquid from the sampling environment towards the bottom of the sampling chamber 7 to ensure a good turnover of the liquid in the sampling chamber 7.

[0074] The strip 11 cooperates with the upstream wall 5 to block the finer sediments that passed through the mesh screen 3. The sediments are then collected in the sediment trap 10.

[0075] The length of each support means 2 is shorter than the width of the side wall 17, 18 of the housing, to allow the cover 15 to be fixed on the upper part of the housing (FIG. 3). As seen in FIG. 1, each support means 2 is a threaded rod pointing upwards to host and secure the detecting means 23, 24. For example, the length of each supporting means 2 can vary form 1.5 cm to 4 cm. In FIGS. 1 & 3, the sampling chamber 7 can host up to two detecting means 23, 24 but this configuration is not restrictive as it can be adapted to host more, for example three detecting means 23, 24 (FIG. 5). The two sets of support means 2 are separated each from the other by a predetermined distance which corresponds to the shape of the detecting means 23, 24 and of the housing dimension. Typically, the distance can vary from 5 cm to 30 cm.

[0076] Each support means 2 is provided with a corresponding detecting means elevating means 22, that allow the detecting means 23, 24 to be at a predetermined distance from the bottom wall 21 of the channel (FIG. 3).

[0077] Each elevating means 22 is fixed at the bottom end of the lower part 2b, in contact with the bottom wall 21.

[0078] As previously mentioned, the role of the sampling chamber 7 is firstly to host the detecting means 23, 24 and secondly to collect and keep enough volume of liquid from the sampling environment to fully immerse the detecting means 23, 24 in order to enable the monitoring of the pollutants and keep the detecting means 23, 24 immersed during the dry periods.

[0079] The width of the upstream wall 5 can be smaller than the width of the sampling chamber 7 by twice the thickness of the mesh screen 3. With such an upstream wall 5 width, the mesh screen 3 can be inserted and secured by the upstream wall 5, the side walls 17, 18 of the sampling chamber 7 and the positioning means 4 having a L shape placed at the front and bottom of the mesh screen 3. To ensure the sealing of the sampling chamber 7, each of the lateral sides of the upstream wall 5 are respectively fixed to each of the corresponding side walls 17, 18 of the channel by two corresponding fixing walls 6.

[0080] The outlet area 13 of the housing is made of the downstream wall 8 of the sampling chamber 7 and the cover 15. The downstream wall 8 is purposively made shorter than the upper edges of both sidewalls 17, 18 of the sampling chamber 7 in order to let an opening when the cover 15 is installed to allow the liquid from the sampling environment to leave the sampling chamber 7 (FIGS. 1, 3 & 6). The grid 31 will block the access to the sampling chamber 7 to any fishes or macroinvertebrates. The grid 31 located at the outlet area has a mesh size in various instances higher or equal to 5 x 5 mm.

[0081] Data feeding the additional information collection system are recorded from probes 16 (FIG. 3) located in the sampling chamber 7 near by the downstream area 13 and the downstream wall 8. These probes 16 are measuring the water level inside the sampling chamber 7 at a frequency defined in the code uploaded in a microcontroller (not shown) and the corresponding data are recorded on a support media, both located outside the sampling chamber 7 in a hermetic box (not shown). Probes 16, microcontroller and data storage are powered by an external battery also located in the hermetic box (not shown).

[0082] The water level probe will monitor the height of the water in the sampling chamber 7 and record the time where the passive samplers 23, 24 were fully immersed in flowing water, the time they were fully immersed in still water and the time they were fully emerged out of the water.

[0083] This additional information collection system can collect any other relevant data with adequate probes.

[0084] The FIG. 4 is a top view of the device 100 (without the cover 15) including the housing and two passive samplers 23, 24, comprising a frame 25 with two membrane supporting means 26, 27 (27 not visible), having a circular shape, diameter of which can vary of from 7 cm to 20 cm, two membranes 28 being clamped therebetween. The membranes 28 have the same shape as the frame 25 and sequester the sorbing material. The sorbing material can be a support of polymeric reversed-phase adsorbent, for example in C18-silica, or activated carbon support. The chemicals that can be retained by the sorbing material are typically selected from the group consisting of pesticides, volatile organic compounds, aromatic derivatives, pharmaceuticals, alkanes, ketones, and aldehydes.

[0085] The frame 25 comprises three fixation means 32 adapted to make the two membrane supporting means 26, 27 clamped each to the other for supporting the membrane 28.

[0086] The two distinct passive samplers 23, 24 are fixed at a predetermined distance from the bottom wall 21 by two threaded rods 2 and two respective elevating means 22, and are cooperating with two corresponding through-hole 29 arranged in the frame 25. The fixation of the passive samplers 23, 24 on the supporting is realised by nuts (not shown). The two passive samplers 23, 24 are parallel to the bottom wall 21.

[0087] The purpose of the device 100 is to be used in shallow sampling environments having a high turbidity, during dry or low flow periods punctuated by flush events rising the liquid level of the sampling environment. This purpose is not restrictive as the device can be used fully submerged during the whole deployment time in a sampling environment having a low turbidity.

[0088] For the first deployment period, the installation of the device consists, in the present configuration, of: [0089] installing at least one passive sampler 23, 24 in the housing at their dedicated places by fixing them to the threaded rods 2, comprising the elevating means 22, with nuts, [0090] closing the device by inserting the two threaded rods 1 through the cover 15 and securing it by screwing a wing nut to each rod 1, [0091] installing the device in the sampling environment with inlet 14 pointing upstream and securing it with its anchorage points 9.

[0092] For the following deployments at the same location, the device can be let in place and the passive samplers 23, 24 exchange by simply removing the hard cover 15.

[0093] Hereafter is described the operating principle of the housing or of the device 100 for the dry or low flow sampling environments punctuated by flush events and for the high flow sampling environments.

[0094] The primarily purpose of housing or of the device is to be used in shallow sampling environments having a high turbidity i.e., during dry or low flow periods punctuated by flush events.

[0095] During dry or low flow periods, the liquid level of the sampling environment is respectively inexistent or too low to reach the top of the upstream wall 5. Therefore, the sampling chamber 7 is disconnected from the sampling environment and the monitoring of the pollutant does not occur.

[0096] When a flush event occurs, the liquid level of the sampling environment is rising, carrying different kinds of foreign materials and suspended sediments. The coarse foreign materials are blocked by the mesh screen 3 and slide along because of its specific shape while the smaller materials are blocked by the finer particle retention system, the heavier materials by the upstream wall 5 and the floating materials by the strip 11 of the cover 15. When the liquid level of the sampling environment reaches the top of the upstream wall 5a, the liquid from the sampling environment, cleaned of a good part of its foreign materials, starts to fill the sampling chamber 7. When the passive samplers 23, 24 get in contact with the liquid, the accumulation of the contaminants onto the sorbing material of the membrane 28 starts. The liquid from the sampling environment leaves the sampling chamber 7 when it reaches the top of the outlet area 13 in the downstream area 8. The flow of the liquid from the sampling environment through the device allows the renewing of the cleaned liquid from the sampling environment in the sampling chamber 7 and therefore the pursuit of the accumulation of the contaminants in the passive samplers 23, 24. The treatment of the liquid from the sampling environment avoids the accumulation of foreign materials on the top of the membrane 28 and thus, the decrease of the contaminant uptake rate.

[0097] At the end of the flush event, the liquid level is decreasing and when it gets bellow the top of the upstream wall 5, the sampling chamber 7 is no longer fed but the passive samplers 23, 24 stay immersed for a period depending of the weather conditions. Therefore, the passive sampling mode changes from the turbulent one to the quiescent one. The uptake rates of the contaminants will decrease with their depletion in the sampling chamber 7 until it becomes negligible. Even if these conditions are not representative of the external conditions, this effect is limited since the depletion of organic pollutants will be completed within a few hours due to a limited volume of sampling chamber 7.

[0098] During the next flush event, the new incoming liquid will replace the old one and the passive sampling starts again. As the membrane 28 from the passive samplers 23, 24 stay hydrated, an increase of the contaminant uptake rate due to the hydration of the membrane 28 will be avoided, as the accumulation process will stay controlled by diffusion.

[0099] The water level probe 16 provides the information on how long lasted the turbulent adsorption mode, the quiescent adsorption mode and the periods where the passive samplers 23, 24 were out of the water. These data will allow a better understanding of the adsorbed masses on the passive samplers 23, 24.

EXAMPLE

[0100] A comparative test was performed where a commercially available device (EST-Lab) was equipped with two passive samplers containing OASIS HLB (Waters) as adsorbing material and where the device according to the invention was equipped with two passive samplers of the same kind. Both devices were exposed at the same time and at the same sampling point. The selected organic contaminants cover a wide polarity range with log Kow values from 0.66 to 3.74. The recovery of each organic contaminant collected via the device of the invention was calculated based on the one from the commercially available device.

[0101] This comparison has been made under field conditions in a mid-mountainous river under steady flow conditions with an exposure time of 14 days.

[0102] The results are presented in FIG. 7, the relative standard deviation in FIG. 8. The recoveries from the device of the invention range from 68% to 104% with an average recovery value of 85%. Even if the values are a bite lower than for the commercially available deployment housing, they stay acceptable.

[0103] For each deployment housing, the relative standard deviations were less than 10% with a couple of exceptions (see FIG. 8).