GB2367302A

GB2367302A - A source of micro-organisms for bioremediation and on site dosing apparatus

Info

Publication number: GB2367302A
Application number: GB0023748A
Authority: GB
Inventors: John Wilfrid Bent
Original assignee: RESPONSE ENVIRONMENTAL TECHNOL
Current assignee: RESPONSE ENVIRONMENTAL TECHNOL
Priority date: 2000-09-28
Filing date: 2000-09-28
Publication date: 2002-04-03
Anticipated expiration: 2020-09-28
Also published as: GB2367302B; GB0023748D0

Abstract

A bio-plug for providing a source of micro-organisms for use in preparing water for bioremediation is claimed. Said bio-plug comprises a sleeve with closed ends containing dried bacterial cultures, dehydrated nutrients and a carbon source, all dispersed in and around a fibre fill, the sleeve having apertures for letting water in and micro-organisms out. Preferably the sleeve is made from high density polyethylene and the fibre is hydrophilic spun polypropylene. Also claimed is an apparatus for dosing on site using said bio-plug comprising a tank, water inlet, float to control the water level, aeration means, heater element and temperature controller, water outlet and submersible discharge pump.

Description

BIOREMEDIATION : SOURCE OF MICRO-ORGANISMES AND APPARATUS FOR DOSING ON SITE This invention relates to bioremediation and more particularly to providing a source of micro-organisms and apparatus for dosing on site to metabolise toxic or hazardous organic t : l substances in an effluent stream or other polluted environment.

It is known to optimise a biomass of micro-organisms within a treatment process

through bio-augmentation, improved bio-processing being achieved and maintained by producing 0 and using those natural micro-organisms found to be effective within the treatment process, such as by utilising a waste stream as the growing medium for the micro-organism.

The effectiveness of bio-augmented treatments is subject to a number of limiting constraints, namely physio-chemical, micro-organism reactivation and survival in the toxic wastes they are to degrade.

Utilising a waste stream as the growing medium can be hazardous because the biological breakdown of certain materials could produce toxins which would kill the micro-organisms thus rendering the process useless.

Many of the processes rely upon standard off-the-shelf consortia of micro-organisms that have been freeze-dried, usually referred to as dried bacterial cultures (DBC), and rely upon human input on a daily basis to rehydrate the micro-organisms prior to operation of the process.

A method of fermentation of micro-organisms is known which comprises adding an inoculum of concentrated mass of micro-organisms to water in a fermenter, adding a growing medium (such as a triptor soya broth), adding a buffer (e. g. phosphates and nitrates) as a nutrient source, aerating the liquor mix, heating the aerated mix to optimum temperature (e. g. 25OC- 27OC), preferably monitoring for oxygen and pH content, and maintaining the optimum temperature for a period to produce the required cell count for the micro-organisms.

The equipment for operating this process tend to be expensive (e. g. in the range f6, 000 to 126, 000 plus) in addition to which there are high installation and running costs. Furthermore, the known equipment are of one size only and tend to be very bulky. Moreover, the output of such equipment tends to be very limited.

GB-A-2 313 833 describes a development of the above method characterised by the steps of homogenising the growing medium by the addition of non-ionic surfactant, adding the homogenised growing medium to the nutrient source, adding the growing medium and the nutrient source to the fermenter, preconditioning the inoculum with the elements of the waste material to be treated, adding the preconditioned inoculum to the fermenter, aerating the contents of the fermenter, and maintaining the optimum temperature for a period to produce the required cell count of the micro-organisms.

The resulting broth may be pumped from the fermenter directly into a waste effluent stream where the micro-organisms biologically metabolise the contaminants in the stream, converting to water and carbon dioxide, resulting in an effluent acceptable for discharge into streams or rivers or sewage systems.

Alternatively, the resulting broth may be fed into or spread over polluted ground.

The nutrient source is preferably natural nitrate, phosphate and potassium (known as

"natural NPK").

GB-A-2 313 833 also describes equipment for carrying out the aforesaid developed method comprising a tank, a mains water supply to the tank, a motorised valve for controlling the water supply, a heater chamber extending upwardly in the tank, a circulation pump within the tank and connected to the lower regions of the heater chamber, a sensor for switching on the circulation pump and the heater in the chamber at a predetermined water level, a return from the regions of the heater chamber to below the water level, an aeration device in the return, an outlet

from the lower regions of the tank, a discharge pump for the outlet, reservoirs for micro-organisms and nutrients, dosing pumps for inoculating the tank contents with controlled amounts of micro-organisms and nutrients from the reservoirs, a water temperature sensor in the tank for activating the inoculating pumps when the water reaches a predetermined temperature approaching the optimum temperature, and a micro-processor for regulating the operation of the valves, pumps and heater.

However, this equipment is difficult to maintain in good working order because of the plurality of valves and pumps with moving parts liable to cease functioning, and is still somewhat expensive due to the number of operative parts and the micro-processor for regulating their operation.

The object of the invention is, therefore, to provide simpler apparatus for dosing on site using a novel source of micro-organisms.

Thus, according to one aspect of the present invention, a source of micro-organisms for use in bioremediation (hereinafter referred to as a"bio-plug") comprises a sleeve with closed ends containing dried bacterial cultures (DBC), dehydrated nutrients and a carbon source, all dispersed in and around a fibre fill, the sleeve having apertures for letting water in and micro-organisms out.

The sleeve may be formed of high density polyethylene (HDP) with series of crosswise slots along two opposite sides, and push-fitting end caps of the same material, but preferably given a distinctive appearance by use of black HDP for the sleeve and yellow HDP for the end caps.

The fibre fill is preferably hydrophilic spun polypropylene, and the carbon source is preferably glucose in powder form, or as a syrup.

The bio-plug preferably floats submerged, and the depth at which it will float can be adjusted by varying the density of the material of the sleeve and/or end caps, but it preferably floats close to the air/water interface for oxygen transfer.

According to another aspect of the present invention, apparatus for dosing on site using the bio-plug comprises a tank, a water inlet into the tank, a float for controlling the inlet in accordance with the level of water in the tank, a heater element in the lower regions of the tank, aeration means in the lower regions of the tank, a temperature controller for the heater element, a water outlet from the tank, and a submersible discharge pump within the tank for pumping water through the outlet.

In use, water enters the tank and continues to fill the reservoir until the level is such that the float causes the water to be cut off, the water in the tank is heated by the submerged heater element and the temperature controller for the heater element sets the water temperature, the water is aerated by the aeration means, a bio-plug is allowed to float in the water to allow the slow release of the bacteria, dry nutrient and carbon, the bacteria released being inoculated in the tank and generating more cells within the inoculated water, and the submersible pump discharges the inoculated water through the outlet.

The float for controlling the inlet is preferably part of a float switch, whereby water only

flows into the tank when the level reaches a lower limit, thus enabling the discharge pump to 1. 9 substantially empty the tank before water again enters it, for the process to begin again.

The heater element is preferably electrical and the aeration means are preferably aeration balls or similar permeable devices (as in a fish tank) supplied by an air pump.

A simple control box with indicator panel for the heater, aeration pump and discharge pump, suffices in place of the micro-processor previously needed; but the discharge pump is preferably duplicated and provided with an automatic change-over switch in the event that one pump becomes disabled, thus avoiding failure of the apparatus and allowing time for maintenance personnel to attend to the disabled pump.

Embodiments of the two aspects of the invention will now be described, by way of

example only, with reference to the accompanying drawings, in which : Figure 1 is a side elevation of a bio-plug ; and Figure 2 is a diagrammatic illustration of the apparatus using a bio-plug.

The bio-plug 10 shown in Figure 1 comprises a sleeve 11, e. g. , of high density polyethylene (HDP), with closed ends formed by end caps 12 of the same material, but preferably given a distinctive appearance by use of black HDP for the sleeve and yellow HDP for the end caps, with the sleeve 11 containing dried bacterial cultures (DBC), dehydrated nutrients and a

carbon source, e. g., glucose in powder form, all dispersed in and around a fibre fill, e. g., of hydrophilic spun propylene (none of which is shown), and the sleeve 11 having apertures 13 in the form of series of crosswise slots along two opposite sides for letting water in and microorganisms out.

In Figure 2 a bio-plug 10 is indicated by a simple rectangle floating close to the air/water interface 14 of water 15 in a tank 16 having a mains water inlet 17 controlled by a float switch 18 (not detailed), whereby water only flows into the tank when the level reaches a lower limit, thus enabling a discharge pump 19 in the lower regions of the tank to substantially empty the tank before water again enters it. A heater element 20 and aeration balls 21 are also installed in the lower regions of the tank 16. The pump 19 discharges through an outlet 22 which leads to contaminated land or effluent (not shown) under treatment.

A control box 23 houses a double pole RCD 30mA twin socket contact breaker 24 with mains power input 25 and fused outputs 26, to the heater element 20 (which is thermostatically controlled to maintain a temperature in the water 15 around 20-30 C) and 27 to a 7-day fused spur time switch 28 having an output 29 to the discharge pump 19 via a changeover switch 30 for the eventuality that if the pump-becomes disabled power can be switched to a duplicate pump (not shown), thus avoiding failure of the apparatus and allowing time for maintenance personnel to

attend to the disabled pump. Another output 31 from the time switch 28 powers an air pump 32 which supplies air to the aeration balls 21 via a manifold 33, but the air pump is not controlled by the timer, being-like the heater element 20-permanently on. All the equipment is powered via the double pole RCD contact breaker 24 as protection.

In use, water 15 enters the tank 16 until the level 14 reaches the upper setting of the float switch 18 at which point the water is shut off. The water in the tank is heated by the submerged heater element 20 until it reaches the thermostat setting of around 20-30oC, and the water is aerated by air pumped through the aeration balls 21.

The bio-plug 10 is placed in the water to allow the slow release of the bacteria, dry nutrient and carbon source into the warm aerated water, an optimum incubation period of 4-12 hours being needed before the discharge pump 19 is first switched on to commence dosing of the water and micro-organismes through the outlet 22.

When the water level 14 reaches the lower setting of the float switch 18 the water at the inlet 17 is turned on again to refill the tank.

The bio-plug will need to be exchanged every 2-6 months depending on the dosage rate, but a check on bacterial activity (and general operation of the apparatus) is recommended at monthly intervals.

The apparatus affords a fully automated system; once the timing has been calibrated no further inputs are required (apart from exchange of bio-plugs). It can be used for the application of biological treatment suspensions for both contaminated land or effluent, to a site at any time of day and dosing can be repeated many times. The apparatus can be manufactured in a range of sizes to suit the method of application and treatment required.

A visual and/or audible-warning-device can be provided to work in conjunction with the changeover switch for the discharge pumps to indicate when one is disabled.

Claims

CLAIMS 1. A bio-plug for providing a source of micro-organisms for use in bioremediation comprising a sleeve with closed ends containing dried bacterial cultures (DBC), dehydrated nutrients and a carbon source, all dispersed in and around a fibre fill, the sleeve having apertures for letting water in and micro-organisms out.
2. A bio-plug as in Claim 1, wherein the sleeve is formed of high density polyethylene (HDP) with series of crosswise slots along two opposite sides, and push-fitting end caps of the same material.
3 A bio-plug as in Claim 2, given a distinctive appearance by use of black HDP for the sleeve and yellow HDP for the end caps.
4. A bio-plug as in any one of Claims 1 to 3, wherein the fibre fill is hydrophilic spun polypropylene.
5. A bio-plug as in any one of Claims 1 to 4, wherein the carbon source is glucose in powder form.
6. A bio-plug as in any one of Claims 1 to 4, wherein the carbon source is glucose as a syrup.
7. A bio-plug as in any one of Claims 1 to 6, and which floats submerged.
8 A bio-plug as in Claim 7 and which floats close to the air/water interface for oxygen transfer.
9. A bio-plug for providing a source of micro-organisms for use in bioremediation substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

9. Apparatus for dosing on site using the bio-plug of any one of Claims 1 to 8, the apparatus comprising a tank, a water inlet into the tank, a float for controlling the inlet in accordance with the level of water in the tank, a heater element in the lower regions of the tank, aeration means in the lower regions of the tank, a temperature controller for the heater element, a water outlet from the tank, and a submersible discharge pump within the tank for pumping water

through the outlet.

10. Apparatus as in Claim 9, wherein the float is part of a float switch, whereby water only flows into the tank when the level reaches a lower limit, thus enabling the discharge pump to substantially empty the tank before water again enters it.

11. Apparatus as in Claim 9 or Claim 10, wherein the heater element is electrical and the aeration means are aeration balls or similar permeable devices supplied by an air pump.

12. Apparatus as in Claim 11 provided with a simple control box with indicator panel for the heater, aeration pump and discharge pump.

13. Apparatus as in any one of Claims 9 to 12, wherein the discharge pump is duplicated and provided with an automatic change-over switch in the event that one pump becomes disabled.

14. A bio-plug for providing a source of micro-organisms for use in bioremediation substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

15. Apparatus for dosing on site substantially as hereinbefore described with reference to the accompanying drawings.

Amended claims have been filed as follows

1. A bio-plug for providing a source of micro-organisms dispersed in water for use in bioremediation comprising a sleeve with closed ends containing dried bacterial cultures (DBC), dehydrated nutrients and a carbon source, all dispersed in and around a fibre fill, the sleeve having apertures for letting water in and micro organisms out.

2. A bio-plug as Claim 1, wherein the sleeve is formed of high density polyethylene (HDP) with series of crosswise slots along two opposite sides, and push fitting end caps of the same material.

3. A bio-plug as in Claim 2, given a distinctive appearance by use of black HDP for the sleeve and yellow HDP for the end caps.

4. A bio-plug as in any one of Claims 1 to 3, wherein the fibre fill is hydrophilic spun polypropylene.

5. A bio-plug as in any one of Claims 1 to 4, wherein the carbon source is glucose in powder form.

6. A bio-plug as in any one of Claims 1 to 4, wherein the carbon source is glucose as a syrup.

7. A bio-plug as in any one of Claims 1 to 6, and which floats submerged in water.

8. A bio-plug as in Claim 7 and which floats close to the air/water interface for oxygen transfer.