Patent ID: 12256768

DETAILED DESCRIPTION

After considering this description it will be apparent to one skilled in the art how the invention is implemented in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, this detailed description of various alternative embodiments should not be construed to limit the scope or breadth of the present invention. Furthermore, statements of advantages or other aspects apply to specific exemplary embodiments, and not necessarily to all embodiments covered by the claims.

Unless the contrary intention is expressed, the features presented as preferred or alternative forms of the invention can be present in any of the inventions disclosed as alone or in any combination with each other.

Throughout the description and the claims of this specification the word “comprise” and variations of the word, such as “comprising” and “comprises” is not intended to exclude other additives, components, integers or steps.

It is not represented that any embodiment of the present invention has all advantages disclosed herein. Some embodiments may provide no advantage and represent only a useful alternative to the prior art.

One embodiment of the present invention provides a method for recovering potable water and solid nutrients from the remaining still bottoms or spent wash that have been distilled to remove alcohol (spent bottoms) after a sugar fermentation. The present invention is applicable to alcohol distillation plants that utilise plant derived fermentable sugars, cellulose-based materials and cellulosic biomass as the substrate for microbial fermentation to produce alcohol.

The method may provide reclaimed potable water that is suitable for reuse in new ferments, or to be used as factory operations water or even drinking water. The highly nutritional solids remaining after water removal by this process can be used as liquid fertilisers or further dehydrated by either industrial driers or by natural heat or weather, to produce animal feed or agricultural fertilisers.

Prior to drying the still bottoms completely, there is the option of further fermentation to produce methane gas for fuel use, prior to use of the residues as liquefied solids as fertiliser for agricultural use.

The present invention provides for the use of forward osmosis in the dehydration of still bottoms, to produce a potable water and wet solid rich fraction. The forward osmosis (FO) draw solution can be selected from an array of potential options such as, but not limited to sodium chloride (NaCl), magnesium chloride (MgCl2), small inorganic and thermolytic salts. The preferred draw solution is sodium chloride. These solutes may be used to commence operation of the RO, and may be augmented as processing continues by the build-up of solutes entering the system by way of input material and being retained in the water-poor fraction of the water removal step.

The Forward osmosis (FO) step is an osmotic process that, like reverse osmosis, uses a semi-permeable membrane to effect separation of water from dissolved solutes. The driving force for FO separation is an osmotic pressure gradient created using a “draw” solution of high concentration. This osmotic gradient is used to induce a net flow of water through the membrane into the draw solution, thus effectively separating the feed water from its solutes.

The schematic process inFIG.2shows the feed liquid (still bottoms) passing through the FO unit. A FO membrane allows interfacing between the feed solution and the draw solution. This figure also shows draw liquid being regenerated using RO to remove clean water as permeate.

The RO water permeate is clean water that may contains only trace amounts of nutrients or residues. This water is directly suitable for use in new ferments, as operations water. If permeate is required for human consumption, it requires contact with activated carbon (such as granular activated carbon; GAC; or powdered carbon either of which may be biologically activated) to remove traces of aromatic and volatile low molecular weight compounds that may passage through the RO molecular weight cutoff point. This water with further treatment such as filtration to remove traces of activated carbon and sterilization or disinfection, will be suitable for human consumption or be potable. It can be used as a source of bottling water.

It is preferred to use low solids and pectin clarified juice processed under an inert gas atmosphere at the natural pH of the juice, and in low light exposure to reduce nutritional oxidation and decay. Sterilisation is preferable carried out by either high pressure sterilisation, UV sterilization or the use of Dimethyl Dicarbonate (DMDC) or other methods that preserve the activity of any nutrient constituents

A zeolite may be used as an alternative to activated carbon. Zeolites are aluminosilicate members of the family of microporous solids, with more common members being analcime, chabazite, clinoptilolite, heulandite, natrolite, phillipsite, and stilbite. Such natural or man-made zeolites can be used to capture and remove molecules on the basis of having pore size greater than the molecular diameter of the molecule to be removed and furthermore, be suitably either hydrophobic or hydrophilic. An example mineral formula is: Na2Al2Si3O10·2H2O, the formula for natrolite.

Another polishing step can include the use of AmberChrom CG-161 to further process the filtration permeate. The AmberChrom resin may be incorporated for the purpose of reducing residual sugar levels to reduce the residual sugar. Detailed application notes for the AmberChrom CG-161 resin may be obtained from Rohn and Haas Company, Philadelphia USA. Functionally equivalent resins are also included within the scope of the present methods. AmberChrom CG-161 may be used to remove aroma and sugar to make the water more neutral in aroma and taste.

The plant-based starting material for the present methods can be a mechanically prepared juice or crush of a plant. Alternatively, the starting material may be a process intermediate of a separate process. For example, the liquid fraction that remains after fruit or vegetable or sugar cane juices have been concentrated commercially is referred to as LSJ (low sugar juice). The processes that produce concentrate and hence LSJ are several including evaporation, filtration (Reverse Osmosis) and freeze concentration.

It will be appreciated that in many circumstances, some pre-treatment of the plant material will be required. Otherwise blockage occurs. For example, processes such as cross-flow filtration or ultrafiltration will be useful. Accordingly, in some embodiments the method comprises the step of pre-treatment.

It will be appreciated that based on the present disclosure, the skilled person could prepare beverages from one (or even a mixture) of the following plants: fruits including orange, apple, tomato, grape, pineapple, mango, berries; coconut milk; sugar cane and the like; vegetables including carrot, celery, beet, pumpkin, and turnip and the like.

In a second aspect the present invention further provides a plant-derived beverage product or process intermediate thereof produced according to a method described herein.

In one embodiment, the product of the present methods has any one or more of the following characteristics:Aroma/odour constituents of more than odour #3A and/or over the threshold odour acceptable for drinking water;Apparent colour or absorbance of more than the sum of the spectrophotometric absorbance at 420 nm and 520 nm of laboratory grade reverse osmosis water when measured through a quartz cuvette having a pathlength of 1 cm;More than about 0.1 Bx sugar, or more than about 0.005 Bx sugar; and/or less than the amount of sugar in an untreated juice.Noticeable taste over and above that of comparable to potable drinking waterMore than about 50 ppm total dissolved solids (TDS);More than about 600 ppm total organic carbon (TOC); andTurbidity more than about 0.5, preferably more than about 0.5 NTU.

In another embodiment, the product of the present methods is very similar to pure water and has any one or more of the following characteristics:Aroma/odour constituents of less than odour #3A and/or under the threshold odour acceptable for drinking water;Apparent colour or absorbance of more than the sum of the spectrophotometric absorbance at 420 nm and 520 nm of laboratory grade reverse osmosis water when measured through a quartz cuvette having a pathlength of 1 cm;Less than about 0.1 Bx sugar, or less than about 0.005 Bx sugar; and/or less than the amount of sugar in an untreated juice.No noticeable taste over and above that of comparable to potable drinking waterLess than about 50 ppm total dissolved solids (TDS);Less than about 600 ppm total organic carbon (TOC); andTurbidity less than about 0.5, preferably less than about 0.5 NTU.

Preferably, the beverage defined above is produced from filter concentrated low sugar juice residues. The low sugar juice may be provided by evaporation, filtration or freeze concentrating. In one embodiment, the process used to produce this embodiment comprises the steps of filtration between about >100 and about <180 Daltons to produce a substantially sugar free water.

The draw solution passing through the FO needs to be regenerated and this can occur through the removal of pure water and leaving the salts behind. Water removal from the draw solution can be achieved by reverse osmosis, nanofiltration, distillation, or by any other means that allows this to happen.

Advantages in using FO rather than RO is the fact that FO membranes do not foul as readily as RO membranes when in direct contact with still bottoms which contain very high levels of organic material and suspended solids. This is due to the fact that particles are likely to be pushed into the pores of RO membranes due to the high pressure exerted on the liquid during filtration.

In contrast, FO membranes are resistant to fouling because there is much less physical pressure on the liquid during FO filtration and suspended solids seldom enter pores of the membrane. Reversed flushing with clean water on a daily basis, often clean the pores of the membrane more successfully than with RO. Thus, using FO will result in consistent water flux from the still bottoms, resulting in drier feed waste. Drier waste, will require less energy to completely dehydrate.

FO membranes are functional within the temperature range of 1 to 95 Celsius and are highly resistant to high chemical concentrations and extreme ph. Still bottoms temperatures often aim to reach around 80 Celsius during ethanol distillation due to the lower boiling point of ethanol relative to water.

Heat energy from the still bottoms can be harvested from the draw solution post FO filtration and prior to draw solution regeneration. The energy in reducing the temperature from around 80 Celsius to 25 Celsius, can be harvested using heat exchangers such as tube in tube type or other types. This eliminates the requirements for expensive heat resistant RO membranes. The heat harvested can then be used where required to offset the cost of running the FO and RO system.

Unlike RO that requires the raw still bottoms to be decanted, ultra-filtered and nano-filtered as a pre-treatment to prevent membrane fouling, the FO membrane only requires either a course screen or a sand filter to function under these highly fouling conditions.

The use of membrane distillation as is evaporation using an evaporator such as the multi-effect or other type is suitable for regenerating the draw solution required for the FO.

Membrane distillation is a thermally driven separation program in which separation is enabled due to phase change. A hydrophobic membrane displays a barrier for the liquid phase, allowing the vapour phase pass through the membrane's pores. The driving force of the process is given by a partial vapour pressure difference commonly triggered by a temperature difference.

To the best of Applicant's knowledge, the prior art fails to teach application of this FO technology that teaches the recovery of water from spent still bottoms after alcohol distillation. The use of FO replaces the existing complex pre-treatments necessary for processing still bottoms by RO for potable water recovery. The remaining still bottom or spent wash fraction after dehydration by FO and RO combined, contains at least and more than 50% total solids, resulting in more water recovery and a waste fraction that requires less energy to dehydrated further if required to produce solid fertiliser.

This waste fraction in the liquid state can be used as a liquid fertiliser or substrate for methane fermentation. The liquid or solid fertiliser can be combined with other ingredients or functional microbes of any type, such as nitrogen fixing bacteria. These microbes can even be microencapsulated to preserve the microbe activity within the fertiliser. Microbes such as the example given will convert atmospheric nitrogen into plant usable nitrogen. Optimising such fertilisers with known nutrients is also the scope of this invention.

Such fertilisers will aim to increase soil fertility with nutrients found in the still bottoms. The additional fortification with microorganisms along with the still bottom solids, will allow propagation of microorganisms into the soils it is spread on or irrigated on.

The present invention provides a simplified process for utilising the remaining still bottoms that have been distilled to remove alcohol (spent bottoms). The process results in reclaimed drinkable potable water that is suitable for use in new ferments, or as factory operations water. The remaining solids after this process can be used as liquid feed stock or liquid fertiliser or, dehydrated by industrial driers to produce dry animal feed or agricultural fertilisers.

Water and fertiliser or animal feed product produced from processing spent bottoms with the technology described in this invention, can reduce the amount of externally sourced operations water and give the factory an additional saleable fertiliser product.

The technology reduces the requirements for decanting and high energy evaporation and collectively, reduces power consumption enormously. The heat recovered from the still bottoms further reduces the cost of operations and if required, the wet solid residues can be further fermented to produce methane fuel before being dried to make agricultural fertilisers.

The advantages of using low fouling Forward Osmosis (FO) prior to RO filtration, is to maintain high flux of dewatering and eliminate further pre-treatment such as decanting, UF and NF, all of which are expensive and complex processes and add to cost of production.

The total solids achievable in still bottoms after FO pre-treatment to RO or NF is at least 50% and more.

The present invention provides in some embodiment a beverage suitable for human consumption. It is proposed that without additional GAC treatment proposed herein, to remove left over organic residues, the water will not be palatable or taste appropriate for human consumption. Furthermore, the water will foul chemically and microbiologically and cannot be stored if not treated with GAC under water storage conditions.

The present invention may utilize a RO or NF as the water removal step. Glucose and fructose can be concentrated by removing most of the water, minerals, ascorbic acid and volatile aromatic and flavour compounds using further filtration via RO. Since MWCO of NF and RO membranes often overlap, either membrane can be used for this step. The MWCO could be any size, but is preferably less than that of the glucose and fructose (MW about 180 Daltons), to retain these sugars from entering the permeate. Reference is made to “The Filtration Spectrum”, Osmonics, Inc., Minnetonka, MN, copyright 1990, 1984.

The permeate, although generally pure, contains low molecular weight aromatics from the source juice and gives the water an aroma and taste, that causes it to differ to the experience of drinking pure water. Furthermore, untreated, the organic load of below 100 Dalton, will sustain microbial growth and water spoilage if stored under conditions used to store drinking water. The use of GAC has not been taught in relation to permeate removed from juices using FO/RO/NF filtration.

It is the purpose of this invention to teach a process of producing operations water and potable water from vegetables, fruit or sugarcane. The process firstly involves producing juice. The juice is then concentrated by any process such as the use of evaporators or part of an evaporator (multi-effect), to remove moisture from the juice. This moisture is recovered as condensate and it is then further processed by Forward Osmosis (FO), Reverse Osmosis (RO) or NF and finally GAC. The resultant water is clean from odour, taste and is suitable for human consumption (potable) and can be used as operations water or be bottled or packaged for sale or human use.

The present invention is distinguished from the prior art document Bento et al teaches the use of thin stillage fraction rather than unprocessed still bottoms for water production. Thus, his process requires prior pre-treatment of still bottoms to removal most solids with either filtration or decanting, centrifugation or gravity.

Bento et al teaches using a plurality of membranes to recover lactic acid and glycerol from corn using the thin stillage of still bottoms. This invention also teaches the production of water through pressurised filtration, which is mineral free and suitable for use in boilers and in ethanol fermentations. This patent does not teach the use of this water for human consumption. In this patent, we are taught that pre-treatment of Still bottoms is essential to prevent fouling of the pressurised RO membrane used. The pre-treatment of raw still bottoms prior to RO filtration includes decanting, UF and NF in series. FO is not considered in replacing these listed pre-treatments prior to RO as a means of preventing fouling.

Kambouris does not teach of removing this first, most contaminated effect prior to treating the condensate by RO filtration or, treating it separately to prevent RO fouling.

One scope of the present invention is to teach the use of FO as a pre-treatment to either RO or NF, or membrane distillation, or other distillation, which is then followed by GAC. This modification to the teachings of Kambouris, effectively allows the first effect of the evaporator to be treated separately, or alternatively, combined with the cleaner effects of the same evaporator, whilst keeping the risk of fouling the RO or NF membrane low. Treating the first effect without discarding it, allows for the recovery of a substantial additional amount of water without causing fouling.

While Peyton discusses the derivation of a water from still bottoms, there is no disclosure whatsoever to the use of FO, let alone in the context of prevention of fouling of other membranes or the further concentration of still bottoms or for the production of a beverage.

The present invention may in some embodiments be considered to provide a synergism in that the combination of the FO and water-removal step in combination provides an unexpected outcome that is more than the additive effects of each component separately. For example, the combination provides the benefits of (i) a means to concentrate a still bottom or beverage concentrate or beverage permeate (such as low sugar juice) (ii) means to improve removal of water form still bottoms so to provide a drier residue (ii) means to provide both a potable beverage and a fertilizer from a still bottom, and (iii) means to reduce fouling of membranes such as RO membranes thereby lessening the need for regeneration or replacement.

A further scope of the present invention is for a process and apparatus for the concentration of juices in particular sugar juice or sugar beet juice or spent wash (ferments with alcohol removed) using Forward osmosis as a pre-evaporator concentration step. The Forward osmosis (FO) step is an osmotic process that, like reverse osmosis, uses a semi-permeable membrane to effect separation of water from dissolved solutes. The driving force for FO separation is an osmotic pressure gradient created using a “draw” solution of high concentration. This osmotic gradient is used to induce a net flow of water through the membrane into the draw solution, thus effectively separating the feed water from its solutes.

The FO technology has not been used in series with an evaporator especially in the sugar and sugar-beet and spent wash concentration industry. It can also be used in the processing of milk and whey.

The FO concentration step proposed may concentrate juices from their physiologically acquired Brix at maturity to a final 40 or 50 Brix. This FO concentration process alone, is not useful for sugar juice or beet juice processing, that aims to produce raw crystalline sugar or molasses and requires much less water in the concentrate for further processing to make the crystallisation process economically achievable. Multi-effect evaporators however on their own, can concentrate such juices to desirable higher Brix levels i.e. 70 to 85 Brix.

The advantage of FO concentration includes the lower cost of the equipment and the running costs during operation. These costs have been compared in the literature as being in the order of 9 times cheaper than an evaporator (FIG.4). It is thus environmentally sustainable and economical to include a pre-concentration step that will achieve an initial concentration of the juices or spent wash at a low operating cost prior to the use of an evaporator or a multi-effect evaporator that will then augment the concentration process to achieve the desired 70 to 85 Brix.

There are several advantages in using FO technology prior to evaporator use in series with an evaporator. These include:(a) The evaporator has less volume to evaporate and could be sized down.(b) The number of effects can be reduced as less surface area is required.(c) The flow rate through existing evaporators can be increased due to lower water removal requirements.(d) Reduced energy, steam, gas water requirements during processing fixed volume liquids.

The evaporator is a piece of equipment that is used to convert a liquid substance such as water into its gaseous-form. The liquid water is evaporated, or vaporised, into a gas form in that process. The vaporised water is then condensed and collected as a liquid again.

Briefly, the evaporators are fed a solution requiring concentrating across a heat source, converting the water in the feed into vapour. The vapour is removed from the rest of the solution and is condensed while the now-concentrated solution is either fed into a second evaporator or is removed.

An evaporator may consist of four sections. These are: firstly, the heating medium, which is often steam that passes through parallel conducting tubes or plates or coils. Secondly, a concentrating and separating section which removes the vapour being produced from the feed solution. Thirdly, a condenser that condenses the separated vapour. Finally, a vacuum system or pump to increase circulation and reducing the pressure within the evaporator and reducing the boiling point of the water.

There are many different types of evaporators in use. These include: natural/forced circulation evaporators, falling film evaporators, rising film (long tube vertical) evaporators, climbing and falling film plate evaporators, multi-effect evaporators and agitated thin film evaporators and others not mentioned.

The most commonly used evaporator type used in sugar cane juice concentration, sugar beet juice concentration and alcohol distillation spent wash concentration, are the multi-effect evaporators.

These multi-effect evaporators unlike single-stage evaporators, can be made of up to seven evaporator stages or effects. The reason for using multiple effects during evaporation is because energy consumption for single-effect evaporators is very high and is most of the cost for an evaporation system.

Multiple effects combined saves heat and energy. In fact, a dual effect evaporator can reduce energy consumption of one single evaporator by 50%. Adding to this another effect can reduce energy consumption to 33% and so on until seven effects are in parallel and no further savings can be obtained due to the actual cost of each effect. The energy saving can be calculated.

Feeding liquid into the multiple-effect evaporators can be either by the forward or backward feeding approach.

The forward feeding approach means that feed liquid enters the system through the first effect, which is at the highest temperature. This feed liquid is then partially concentrated as some water is removed before being fed into the lower temperature second effect and so on. The second effect is heated by the vapour removed from the first effect (hence the saving in energy expenditure). This continues throughout the effects in series and the combination of lower temperatures and higher viscosities in subsequent effects provides an increase in the heating surface area.

In contrast, in backward feeding, the last effect has the lowest temperature and is fed the liquid being concentrated and the liquid moves effects whilst the temperature in these effects increases. The final concentrate is collected in the hottest effect, which provides an advantage in that the product is highly viscous in the last stages, and so the heat transfer is better.

The schematic process inFIG.2shows the feed liquid (still bottoms) passing through the FO unit. A FO membrane allows interfacing between the feed solution and the draw solution.

The draw solution passing through the FO needs to be regenerated and this can occur through the removal of pure water and leaving the salts behind. Water removal from the draw solution can be achieved by reverse osmosis, nano-filtration, membrane distillation, or by any other means that allows this to happen.

Advantages in using FO rather than RO is the fact that FO membranes do not foul as readily as RO membranes when in direct contact with spent wash or juice which contain very high levels of organic material and suspended solids. This is because particles are likely to be pushed into the pores of RO membranes due to the high pressure exerted on the liquid during filtration.

In contrast, FO membranes are resistant to fouling because there is much less physical pressure on the liquid during FO filtration and suspended solids seldom enter pores of the membrane. Reversed flushing with clean water daily, often clean the pores of the membrane more successfully than with RO. Thus, using FO will result in consistent water flux from the spent wash or juice, resulting in drier solution entering the evaporator. Drier solutions will require less energy to completely dehydrate.

FO membranes are functional within the temperature range of 1 to 95 Celsius and are highly resistant to high chemical concentrations and extreme ph. Spent wash temperatures often aim to reach around 80 Celsius during ethanol distillation due to the lower boiling point of ethanol relative to water.

Heat energy from the spent wash can be harvested and added to the draw solution post FO filtration and prior to draw solution regeneration when using membrane distillation. The energy in reducing the temperature from around 80 Celsius to 25 Celsius, can be harvested using heat exchangers such as tube in tube type or other types. This eliminates the requirements for expensive heat resistant RO or NF membranes if these are required. The heat harvested can then be used where required to offset the cost of running the FO and RO system. Alternatively, heat harvested from the evaporator condensates can be used to heat the draw solution prior if membrane distillation is the preferred draw solution regenerative process.

Membrane distillation is a thermally driven separation program in which separation is enabled due to phase change. A hydrophobic membrane displays a barrier for the liquid phase, allowing the vapour phase to pass through the membrane's pores. The driving force of the process is given by a partial vapour pressure difference commonly triggered by a temperature difference.

Unlike RO that requires the spent wash to be decanted, ultra-filtered or Nano-filtered as a pre-treatment to prevent membrane fouling, the FO membrane only requires either a course screen or a sand filter to function under these highly fouling conditions.

The invention can be described as a new option other than adding effects to an existing single evaporator or, a multi-effect evaporator that already has the maximum number of effects or efficiency and is energy use expensive.

Adding FO in series prior to existing evaporators to pre-concentrate, reduces the overall processing costs and capital costs of expanding evaporators. This leads to a reduction in the use of power, steam, water and heating for concentrating a given volume of juice or liquid solution.

The invention requires the use of Forward Osmosis filtration technology to pre-concentrate or de-water the juice to a mid-level of concentration, prior to concentrating the juice to the final desired level using an evaporator.

Sugar cane juice commercially extracted from sugar cane at maturity after the addition of chemicals and clarified is around 13 Brix. Within the evaporator, the juice is recirculated until the final Brix departing the evaporator increases to between 70 to 75 Brix.

A sugar juice concentration process was carried out. The amount of sugar cane juice processed by evaporation was 325 tonnes per hour through a multi-effect evaporator. The juice contained 87% water and for every 5.18 tonnes of water removed from the juice through the evaporator, 1 tonne of steam was consumed.

Using FO to reduce the water contents of the sugar juice by only 26% in a sugar mill that crushes 7,000 tones sugarcane per day, saved the use of 400 tonnes per day steam by a 5-effect evaporator and about 175 tonnes/day bagasse.

Plant materials are utilized on an industrial scale to produce a wide range of products including alcohol. A plant-derived material containing sugar is incubated with yeast, with the yeast metabolically converting the sugar to alcohol. A common use of fermentation is by distilleries that utilize plant sugars such as molasses to produce alcohol. First, molasses is diluted by adding water to adjust the total dissolved solids to about 7-8% before adding yeast, nitrogen and other required nutrients for fermentation to commence. At the end of this ferment, when glucose is converted to ethyl alcohol and carbon dioxide, the solution is referred to as a beer solution. The CO2is collected during its production and the alcohol is harvested through a distillation column. The diagrammatic representation of the process can be seen inFIG.2.

As with sugar juice and sugar-beet juice concentration, the aim of concentrating spent wash is to reduce the amount of water in the effluent spent wash as much as possible and as cheaply as possible. The water removed from the spent wash by either the evaporator or FO unit should be of the quality for operations or even potable water standards. Others have already described this source of water for use as operations and potable water suitable for drinking and boiler and solvent and cooling tower use.

Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in this field.