GB2313833A

GB2313833A - Cultivating micro-organisms for managing waste effluent

Info

Publication number: GB2313833A
Application number: GB9711066A
Authority: GB
Inventors: John Bent
Original assignee: TOJA AMSTERDAM BV
Current assignee: TOJA AMSTERDAM BV
Priority date: 1996-06-04
Filing date: 1997-05-30
Publication date: 1997-12-10
Anticipated expiration: 2017-05-30
Also published as: GB9711066D0; GB9611635D0; GB2313833B

Abstract

A method of cultivating micro-organisms comprises adding an inoculum of concentrated mass of micro-organisms to water in a fermenter, adding a growing medium, adding a buffer as a nutrient source, aerating the mixture, heating the aerated mix to optimum temperature, and optionally monitoring for oxygen and pH content, wherein the growing medium comprises the elements of the waste material to be treated. The method is characterised by the steps of (a) homogenising the growing medium by the addition of non-ionic surfactant, (b) adding the homogenised growing medium to the nutrient source,(c) adding the growing medium and the nutrient source to the fermenter,(d) preconditioning the inoculum with the elements of the waste material to be treated (e) adding the preconditioned inoculum to the fermenter,(f) aerating the contents of the fermenter and (g) maintaining the optimum temperature for a period to produce the required cell count of the micro-organisms. The buffer nutrient source may consist of phosphates and nitrates. Equipment for carrying out the method is also disclosed.

Description

MANAGING WASTE EFFLUENTS ETC.

This invention relates to managing waste effluents and other contaminants using natural organisms to metabolise toxic or hazardous organic 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 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 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. 250C 27"C), 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 6,000 to 6,000 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.

The object of the present invention is to provide a method of fermentation of micro-organisms that overcomes the above-mentioned disadvantages.

Another object is to provide equipment for carrying out the method that is comparatively inexpensive, less bulky, and more readily manageable than known equipment.

According to the present invention a method of fermentation of micro-organisms comprises adding an inoculum of concentrated mass of micro-organisms to water in a fermenter, adding a growing medium, adding a buffer as a nutrient source, aerating the liquor mix, heating the aerated mix to optimum temperature, and optionally monitoring for oxygen and pH content, and is characterised in that the growing medium comprises the elements of the waste material to be treated, and 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").

Equipment for carrying out the method comprises 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 upper 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.

The manner of operation, which is totally automated, is as follows: Upon start-up the mains supply valve is opened to fill the tank until at the predetermined water level the level sensor activates the circulation pump and the heater, and closes the main supply valve. Water will then circulate through the heater chamber and the return with the aeration device.

When the water temperature reaches 20"C (plus or minus 0.5"C) the water temperature sensor will activate the dosing pumps which will inoculate the tank with controlled amounts of microrganisms and nutrients, and the temperature will continue to rise to 27"C (plus or minus 0.5"C), which temperature level is maintained until discharge.

At a predetermined time in the programme cycle the heater will be switched off and the discharge pump will be switched on, for the contents of the tank to be discharged into the effluent stream or to the area for treatment.

After a predetermined drain time the main supply valve opens to sluice out the remaining contents ofthe tank, and after a predetermined sluicing time the discharge pump is switched off, whereafter the mains supply starts to refill the tank, for the processing cycle to be repeated.

The micro-processor preferably has a control unit with a fail light-off warning system for all the operations, and preferably also has override commands should the equipment need to be operated manually.

A hand-operated drain valve is preferably provided at the bottom of the tank in case it needs to be drained, e.g. in the event of a pump malfunction.

The mains water supply may be controlled by a solenoid valve responsive to the water level sensor, and the inoculation of micro-organisms and nutrients may be metered by timed peristaltic dosing pumps.

The aerating device in the retum from the heater chamber to below the water level in the tank may be a venturi chamber with an air intake.

The tank is preferably provided with an overflow just above the high water level.

An embodiment of equipment in accordance with the invention, and its manner of operation, will now be described, by way of example only, with reference to the accompanying diagrammatic drawing.

The equipment comprises a tank 1, a mains water supply 2 to the tank, a motorised valve 3 for controlling the water supply, a heater chamber 4 extending upwardly in the tank, a circulation pump 5 within the tank and connected to the lower regions of the heater chamber, a sensor 6 for switching on the circulation pump and the heater in the chamber at a predetermined water level L, a return 7 from the upper regions of the heater chamber to below the water level, an aeration device 8 (with an air inlet 9) in the return, an outlet 10 from the lower regions of the tank, a discharge pump 11 for the outlet, reservoirs 12, 13 for micro-organisms and nutrients, dosing pumps 14, 15 for inoculating the tank contents with controlled amounts of microorganisms and nutrients from the reservoirs, a water temperature sensor 16 in the tank for activating the inoculating pumps 14, 15 when the water reaches a predetermined temperature approaching the optimum temperature, and a micro-processor (not shown) for regulating the valves, pumps and heater.

Upon start-up the mains supply valve 3 is opened to fill the tank I until at the predetermined water level the level sensor 6 activates the circulation pump 5 and the heater in the chamber 4, and closes the main supply valve 3. Water will then circulate through the heater chamber 4 and the return 7 with the aeration device.

When the water temperature reaches 20"C (plus or minus 0.5 C) the water temperature sensor 16 will activate the dosing pumps 14, 15 which will inoculate the tank 1 with controlled amounts of micro-organisms and nutrients from the respective reservoirs 12, 13 and the temperature will continue to rise to 27"C (plus or minus 0.5"C), as controlled by a thermostat 17, which temperature level is maintained until discharge. An overheat thermostat 18 is provided to switch off the heater in an emergency. The dosing pumps 14, 15 affect metering ofthe microorganisms and nutrients by their periods of operation being controlled by respective timers 19, 20 incorporated in the micro-processor.

At a predetermined time in the programme cycle, e.g., six hours after start-up, the discharge pump 11 will be switched on (as by a clock timer 21 operating through an automatic switch 22 with a manual override) for the contents of the tank 1 to be discharged through the outlet 10 into an effluent stream or on to an area for treatment (neither shown nor indicated).

After a predetermined drain time, e.g. five minutes (as determined by a timer 23 and a sluice controller 24 for the main supply valve 3) the main supply valve opens to sluice out the remaining contents of the tank, and after a predetermined sluicing time, e.g. two minutes (as determined by a timer 25 for the discharge pump) the discharge pump 11 is switched off, whereafter the mains supply 2 starts to refill the tank, for the processing cycle to be repeated.

A hand-operated drain valve 26 is provided at the bottom of the tank 1 in case it needs to be drained e.g. in the event of a pump malfunction, and the tank is also provided with an overflow 27 just above the water level L.

Claims

1. A method of fermentation of micro-organisms comprising adding an inoculum of concentrated mass of micro-organisms to water in a fermenter, adding a growing medium, adding a buffer as a nutrient source, aerating the liquor mix, heating the aerated mix to optimum temperature, and optionally monitoring for oxygen and pH content, characterised in that the growing medium comprises the elements of the waste material to be treated, and characterised by the steps ofhomogenising 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.

2. A method as in Claim 1, wherein the nutrient source is natural nitrate, phosphate and potassium.

3. Equipment for carrying out the method of Claim 1, 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 upper regions of the heater chamber to below the water level, an aeration device in the return, an outlet from the lower regions ofthe 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.

4. Equipment as in Claim 3, wherein the micro-processor has a control unit with a fail light-offwarning system for all the operations.

5. Equipment as in Claim 4, wherein the micro-processor also has override commands should the equipment need to be operated manually.

6. Equipment as in any one of Claims 3 to 5, wherein a hand-operated drain valve is provided at the bottom of the tank in case it needs to be drained.

7. Equipment as in any one of Claims 3 to 6, wherein the mains water supply is controlled by a solenoid valve responsive to the water level sensor.

8. Equipment as in any one of Claims 3 to 7, wherein the inoculation of micro-organisms and nutrients is metered by timed peristaltic dosing pumps.

9. Equipment as in any one of Claims 3 to 8, wherein the aerating device in the return from the heater chamber to below the water level in the tank is a venturi chamber with an air intake.

10. Equipment as in any one of Claims 3 to 9, wherein the tank is provided with an overflow just above the high water level.

11. Manner of operating equipment for carrying out the method of Claim 1 substantially as hereinbefore described with reference to the accompanying drawing.