KR20080019084A - Catalytic bioconversion of petroleum-contaminated wastes/wastewaters using kenaf core powder - Google Patents

Abstract

Catalytic bioconversion processes using kenaf core powder are provided to make hazardous waste harmless and to generate useful solid fuel products from waste by recovering high quality hydrocarbons. A method for treating petroleum-contaminated waste/wastewater comprises the steps of: introducing kenaf core powder(12) into petroleum-contaminated waste/wastewater at a ratio of 100 to 5000 mg/L; processing the petroleum-contaminated waste/wastewater and the kenaf in a bio-reactor(13); and dehydrating a mixture of the petroleum-contaminated waste/wastewater and the kenaf to produce a bio-solid material. The method comprises a step of producing a biomass fuel by drying the bio-solid material after performing the dehydration process, and a clarifier step performed before directly sending settled solids of a clarifier(14) to the bio-solid dehydrating step.

Description

Catalytic Conversion of Petroleum-Contaminated Waste / Wastewater Using Kenaf Core Powders {CATALYTIC BIOCONVERSION OF PETROLEUM-CONTAMINATED WASTES / WASTEWATERS USING KENAF CORE POWDER}

Brief description of the drawings

1 shows a process flow diagram illustrating the invention.

Field of invention

The present invention relates to the treatment of petroleum-contaminated waste / wastewater generated by the petroleum refining and / or petrochemical industry, and more particularly to producing high energy solid fuels for use in industrial cement plants and / or power plants. In order to facilitate environmentally friendly methods for the biological treatment of petroleum contaminants in such wastes, it relates to a catalytic conversion (CB) method using kenaf core powder.

Background of the Invention

Hazardous wastes and waste waters generated by the petroleum industry (K048, K049, K051, K037, and K038) are emulsion mixtures of solids, water, and oils that are very difficult to treat, transport and dispose of. These wastes cannot be used directly as fuels without significant dehydration in their original state, as well as because of their high solids content they cannot be easily transported in conventional liquid tanks. The costs associated with dewatering, transporting and disposing of these wastes are very heavy for the petroleum refining and petrochemical industries. At present, refineries and petrochemical devices use compression filters, high speed centrifuges, and thermal desorption to process such waste and wastewater. These processes in use today require significant capital investments with enormous operating costs. More importantly, they have to produce waste materials that are classified as hazardous wastes and either calcinate them or constantly mandatory landfills at significant costs. The financial costs and obligations associated with dehydration, transportation and disposal of these wastes are very burdensome for the petroleum and petrochemical industries.

The preceding patents discussed below define the manufacture of fibers for use in waste treatment and generally discuss the drawbacks of the necessary dehydration of using absorbent materials in the treatment of waste materials.

A process for separating kenaf into cores and fibers is described in US Pat. No. 5,970,582. Disclosed are a method and apparatus for separating kenaf into fibers and cores using modified stick machines typically used to remove waste from uncooked cotton in the cotton industry. The length of the kenaf is carried over the circumference of the circular saw and the gears interfere with the fiber and pull the kenaf across the metal grid. The core is separated from the fiber, passes through the grating, and is carried to the core outlet. The fibers on the tooth are removed by the doping wheel and carried to the fiber outlet. A plurality of cylindrical saw / doped wheel assemblies is provided.

Typical wastewater sludge stabilization processes are disclosed in US Pat. Nos. 4,781,842 and 4,902,431, where sewage sludge is stabilized and converted to fertilizer by mixing with sufficient alkaline material to raise the pH to at least 12. The mixture is then dried for at least one day. Alkaline materials for achieving chemical stabilization are selected from cement, kiln dust, and lime dust. Bulk materials such as slag powder, fly ash, gypsum, and the like may also be added. This process is mainly a drying process to remove unpleasant odors and pathogenic microorganisms. This process cannot produce a substantial amount of heat that will destroy many of the contaminants found in the process.

U. S. Patent No. 6,027, 652 describes one process for alleviating environmental problems associated with the production of oils or chemical absorbers using absorbent systems based on natural fibers. Over the last few decades, a wide variety of treated natural fibers have been used as absorbents of hazardous substances. These include henna, peat, wood fibres, dialginate kelp, powdered lily, kenaf cores, inflated cereals, and various other cellulosic materials. Each of these fiber types has the drawback of not being the material of choice for improving oil and chemical spills on land or water. The major drawback of most of these fiber types is that the patent mentions that they are inherently hydrophilic and tend to absorb large amounts of water. Absorption of water increases the weight of these materials and can significantly reduce their ability to absorb oils or hazardous chemicals that these materials attempt to recover. Treatment with chemical additives to increase their hydrophobicity can reduce or eliminate to some extent the tendency of these materials to absorb water.

In US Pat. No. 5,021,390, Hatton discloses a composition for absorbing liquids, consisting of various fibrous plant materials treated with sodium methyl silicate, which is a waterproofing agent. In US Pat. No. 5,492,881, Diamond discloses an absorption system that uses finely ground cellulose treated with hydrophobic agents such as paraffin, other waxes, polyvinyl alcohol, hydroxyethyl cellulose, and the like. These additives are added to the manufacturing cost of the absorbent and by themselves can be another source of harm to the environment.

Another drawback of the already disclosed natural fiber based absorbents disclosed in the prior art is that most of them can generally absorb only 5-10 times the weight of these absorbents in oil or other chemicals. In addition, most of these natural fibrous compositions tend to sink when saturated with oil, water or other chemicals, making recovery of these and absorbed chemicals from the water body particularly difficult or impossible.

Summary of the Invention

The present invention is a catalytic bioconversion (CB) process that uses kenaf core powders to produce a high energy solid fuel and at the same time facilitate the biological treatment of petroleum contaminants present in waste and wastewater in an environmentally friendly manner. . This new process has very low capital and operating costs, and can process and convert hazardous waste into non-hazardous waste and produce useful solid fuel products instead of waste. Typically, such petroleum-contaminated waste / wastewater undergoes several types of hydrocarbon separation and recovery through phase separation using heat and chemical treatment in storage tanks. It is an object of the present invention to recover as many "good" hydrocarbons as possible and to recycle them back into the manufacturing process. Unrecovered materials, oils, water and solid emulsions must be further processed and eventually discarded.

In the present invention, the kenaf core powder is introduced into the waste / wastewater stream using a very simple in-line eductor injection system at a rate of 100 to 5000 mg / L (after the first hydrocarbon recovery is attempted). Due to the high absorbency of the powder, Kenaf core powder instantly “catches up” the organic load portion in petroleum-contaminated waste / wastewater streams. The waste / waste and kenaf mixtures are then sent to a biological treatment system that includes a bioreactor for organic treatment and a centrifuge for separation of solids. Kenaf core powder particles essentially contain approximately 45% glucose and 2% protein, an energy source useful for microorganisms in biological processing systems. As a result, kenaf core powder particles create a site for the microorganism that provides a rich food consisting of organic loads that have been absorbed and naturally produce glucose and protein. Moreover, kenaf core powder contains and provides a number of unique microorganisms for naturally important nutrients (phosphorus, nitrogen, sulfur, calcium, potassium, and others), biological systems.

The total effect on the biological system is a much stronger and more useful microbial population in biological treatment systems. As a result, the system is less susceptible to shock loads (organic, toxic, swings at pH loads) and in this case will recover much faster. During normal load, the treatment sufficient to remove contaminants will be improved, creating an opportunity to increase the load on the biological system (the system can handle additional hydraulic loads). Most importantly, it can reduce or eliminate the expensive chemicals (pH regulation and / or nutrients) currently added to biological systems.

When microorganisms absorb the natural carbohydrates in Kenaf, individual bacterial cells produce protective outer shells composed of glycocalyx. Such protective shells are an important factor in providing biological entities with the ability to survive in toxic environments inherent in the treatment of the waste / wastewater. The organic and inorganic removal efficiencies obtained through the CB treatment process produce solids that are no longer classified as harmful.

The benefits to the treatment system are not limited to biological treatment systems (bioreactors). In addition, the carbohydrate portion in the kenaf core powder is composed of hemi-cellulose. Some of the hemi-celluloses are not consumed by microorganisms in biological systems and become important substrates in solids that are discarded from the system. These solids will dehydrate water better than solids that do not contain hemi-cellulose, and will dry faster, which can be dried and pelletized more economically. Improved dehydration of waste activated sludge can reduce or eliminate chemical treatment of solids. In addition, since the solids contain hemi-cellulose, they now have much more thermal energy content. Dried and pelletized sludge can be used as biomass fuel in cement kilns or power plants.

Description of Preferred Embodiments

1 is a flow diagram of a process in which kenaf powder 12 is introduced into an incoming waste / wastewater stream 11 using an in-line injection system at a rate of 100 to 5,000 mg / liter. Untreated waste / wastewater flow rates generally range from 5 to 500 gallons per minute. Kenaf powders mixed with waste / wastewater streams immediately “grab” some of the organic load due to their high absorption. Waste / wastewater streams and kenaf are mixed and introduced into bio-reactors where microorganisms and other elements destroy organic matter. The treated liquid is sent to a clarifier 14 where the solid is separated from the liquid. Solid 16 is pumped into the bio-solid dewatering zone, and a portion of the solid 19 (10% to 50%) may be returned to the bio-reactor 13 for further processing. The solid 17 in the bio-solid dehydration zone is dehydrated, water is returned to the bio-reactor 18, and the dehydrated solid 20 is subjected to a solid drying process 21. The dried solid is then processed and stored 22 for use as fuel.

Kenaf powder particles used in this process originally contain approximately 45% glucose and 2% protein, a useful energy source for microorganisms in biological systems. As a result, kenaf powder particles create sites for microorganisms that provide absorbed organic loads and abundant foods consisting of naturally occurring glucose and proteins. Moreover, kenaf powders inherently contain important nutrients (phosphorus, nitrogen, sulfur, calcium, potassium, and other nutrients) along with a large number of native microorganisms and provide them to biological systems. The total effect on the biological system is a much stronger and more useful microbial organism in the biological system. As a result, the system is less susceptible to shock loads (organic, toxic, or swings at pH loads) and will recover much faster from this case. During typical loads, the treatment efficiency for contaminant removal will be improved, thereby creating an opportunity to increase the load on the system. Most importantly, it is possible to reduce or eliminate expensive chemicals (pH regulation and / or nutrients) currently added to biological systems.

When microorganisms absorb the natural carbohydrates in kenaf, a protective outer shell consisting of glycocalyx is produced by individual bacterial cells. Such protective shells are an important factor in providing biological entities with the ability to survive in toxic environments inherent in the treatment of the waste / wastewater stream. The efficiency of organic and inorganic removal in bioreactors produces solids that are not classified as hazardous waste. Glycocalix also functions as a flocculant by "sticking" smaller suspended solids together to form larger and heavier particles in the final clarifier. Larger and heavier solid particles produce biomass sludge that is better and sinks faster. Treatment systems that use coagulants and flocculants to improve precipitation may reduce or eliminate the use of these chemicals.

The advantages for wastewater treatment plants are not limited to biological systems (bioreactors). Solids discarded from biological systems are better dehydrated and have a much faster drying time. The improved dehydration and drying properties of the solids can lead to the removal of the dehydration process in some treatment plants. More importantly, since the solids now contain kenaf powder, they can be more economically dried and pelletized, which can contain higher thermal energy values. The dried solid may then be shipped to the cement kiln or power plant as biomass fuel.

Cement kilns release large amounts of CO ₂ , one of the most important greenhouse gases (GHGs). CO ₂ from the Cement Manufacturing Industry Release is by two different processes. First, limestone must be heated to approximately 2600 ° F to produce cement products. This requires the combustion of large amounts of fossil fuels (usually coal). Second, when limestone is heated, limestone undergoes a process called calcination and releases large amounts of CO ₂ . Since limestone must be heated and calcined to produce cement, the cement industry has very limited options in dealing with GHG (CO ₂ ) emissions and their reduction. There is a major way in the cement industry to find a solution to this problem.

Biomass fuels made from dried and pelletized solids can provide a cement source with a CO ₂ reduction record. This biomass fuel is renewable and depleted because it consists of kenaf powder and other biomass. It is produced by replacing the rich fossil fuels to biomass fuels was isolated from the atmosphere - CO ₂ reduction results for kenaf growing carbon.

Another advantage of using the biomass fuel in cement kilns is the ability of the cement kiln to utilize inorganic solids (ash) that are part of the burned biomass fuel. These inorganic solids become part of the cement manufacturing raw material and actually provide increased production for the cement plant.

Considering the CO ₂ reduction and increased production, the fuel should be comparable to high-grade coal. Kenaf core powder enhances biological activity in activated sludge wastewater treatment, improves precipitation of biological solids in the final clarifier, and improves dehydration and drying properties of the solids.

Kenaf core powder provides a natural, cost-effective alternative to expensive chemical treatment programs. Kenaf core provides advantages for all aspects of biological treatment systems. Expensive chemical treatment programs for nutrient additions, coagulant and flocculant additions, and dehydration are significantly reduced or eliminated. Kenaf core powder is a natural, environmentally safe product that is not synthesized. Kenaf core powder is fully biodegradable and does not introduce chemical residues into the environment. Dried and pelletized hemi-cellulose reinforced solids are much easier to handle and transport. This creates a product that generates potential revenue for waste that must be sent to landfill for disposal.

Claims (15)

Methods for treating petroleum-contaminated waste / wastewater, including the following steps: Introducing kenaf powder into petroleum waste / wastewater; Processing the petroleum-contaminated waste / wastewater and kenaf in a bio-reactor; And Dewatering the petroleum-contaminated waste / wastewater and kenaf mixture to produce a bio-solid material. The method of claim 1 wherein the kenaf powder is a kenaf core powder. The method of claim 1, wherein the kenaf powder is introduced into the petroleum-contaminated waste / wastewater at a rate of 100 to 5,000 mg / liter. The method of claim 1, wherein after the dehydration process, the bio-solid material is dried to produce a biomass fuel. The method of claim 1, comprising a purifier step prior to directing the precipitated clarifier solids to the bio-solid dewatering step. Methods for treating petroleum-contaminated waste / wastewater, including the following steps: Introducing kenaf powder into petroleum-contaminated waste / wastewater; Processing the petroleum-contaminated waste / wastewater and kenaf in a bio-reactor; Processing the petroleum-contaminated waste / wastewater and kenaf mixture in a clarifier; And Dewatering the treated petroleum-contaminated waste / wastewater and kenaf mixture to produce a bio-solid material. 7. The method of claim 6, wherein said kenaf powder is a kenaf core powder. 7. The method of claim 6, wherein the kenaf powder is introduced into the petroleum-contaminated waste / wastewater at a rate of 100 to 5,000 mg / liter. 7. The method of claim 6, wherein after the dewatering process, the bio-solid material is dried to produce biomass fuel. A method of making a biomass fuel, comprising the following steps: Mixing kenaf with petroleum-contaminated waste / wastewater; Processing the petroleum-contaminated waste / wastewater and kenaf in a bio-reactor; And Dewatering and drying the biomass solids produced from the bio-reactor processed petroleum-contaminated waste / wastewater and kenaf. The method of claim 10, wherein the kenaf powder is a kenaf core powder. The method of claim 10, wherein the kenaf powder is introduced into the petroleum-contaminated waste / wastewater at a rate of 100 to 5,000 mg / liter. The method of claim 10, wherein after the dehydration step, the bio-solid material is dried to produce a biomass fuel. 11. The method of claim 10, comprising a purifier step prior to directing the precipitated purifier solids to the bio-solid dehydration step. 7. The method of claim 6, comprising separating the bio-solid material from the effluent of the clarifier.

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