Method of algal water movement in the algal cultivation systems through gravity-fed gaps to get maximum immersed artificial light exposure and to enhance productivity

Abstract

Algae cultivation system is an increasingly important field due to their versatility and the high biomass yield produced. The continuous movement and Mixing of Algal Water will help Algal cell to get exposed to light source. Light availability the algal culture depends on the thickness of the system where algal culture is moving. The thin layers of algal culture also facilitate efficient gas exchange, ensuring that carbon dioxide is readily available for photosynthesis and oxygen is effectively removed, preventing oxygen accumulation that could inhibit growth. Algae requires few seconds of light exposure to start its photosynthetic activity. This light availability and culture movement has created huge difference between the laboratory and mass scale productivity. There is a need for a simple, energy-efficient system which makes algal cells to get maximum exposure to light.

Description

[0001]METHOD OF ALGAL WATER MOVEMENT IN THE ALGAL CULTIVATION SYSTEMS THROUGH GRAVITY-FED GAPS TO GET MAXIMUM IMMERSED ARTIFICIAL LIGHT EXPOSURE AND TO ENHANCE PRODUCTIVITY FIELD OF THE INVENTION This invention pertains to the field of algae cultivation systems, specifically focusing on methods and systems for large-scale algae cultivation in equipment such as tanks, ponds, and tubes in order to achieve high productivity with low capital costs BACKGROUND OF THE INVENTION Algae has unable to penetrate in to human life due to low output in mass-scale production, resulting in high costs for algal products. A significant gap exists between laboratory-scale production and large-scale industrial systems. Algae grow best when certain optimal conditions are available. Microalgae cultivation requires specific environmental conditions including temperature ranges, light intensities, mixing conditions, nutrient composition, and gas exchange. This makes outdoor algae cultivation impractical in colder and warmer climates, as the conditions for growth occur only through certain part of the year at best; in addition to this, the natural conditions are subject to modification to a highly limited extent. However, unlike most multicellular plants, algae do not require fertile soil, fresh water and have a limited need for space. As a result, algae can be grown in specially prepared cultivation systems or photobioreactors. These special systems not only allows for year-round cultivation of algae, but also for the adjustment of conditions such as, e.g., light, air, temperature and contamination free protected environment gives optimal growth rate. Moreover, these Special Algal cultivation systems in large capacities produces higher amount of algal biomass compared to current existing systems like Racewayponds. Therefore, development of these high yielding algal growth systems remain an important and promising segment. The high productivity of algae depends on a number of factors like wavelength and times of light exposure, temperature, CO2 availability and nutrients are important. The circulation of Algal culture inside the system plays a vital role in getting light for photosysnthasis in the Algae and this is one of the high energy consuming segment in the Algal cultivation. The dynamics of aeration is another key parameter for improving the growth of microalgae cells. Aeration promotes pH regulation, aids mixing, and allows the elimination of nutrient concentration gradients. It promotes the even exposure to light radiation for all the cells and helps to release the oxygen produced in the bottom there by to reduce its toxic effect on microalgae. As mentioned above, light energy significantly determines the growth rate Algal Biomass, and its influence is different for different species cultivation. Both excessive and insufficient lighting have a negative impact on the amount of biomass. In the Algae cultivation the light penetration is proportional to the density of the Algae culture. With the increase in the density the light penetration get reduced. This effects the availability of light to the algae cells in the depths. It is believed light cannot penetrate beyond 5 cm in the algal culture due to self-shading of the algal cells. In addition to the above, the self-shading of microalgae cells reduces the intensity of light within the Algae Cultivation system. Located farther from the source of light, they will receive less radiation as a result of mutual occlusion, which results in a decrease in the rate of growth. As the cell density increases, the intensity of light in the reactor is suppressed. Microalgae has efficient nature of light harvesting even at low light intensities, which gives them the ability to reach very high cell densities. Extensive research has been conducted to create culture conditions where light can be evenly distributed. To achieve even light distribution, parameters, such as liquid depth and mixing, play key roles. For Algal cultures using artificial lighting, light-emitting diodes (LEDs) are most often used to illuminate photobioreactors. LEDs emit radiation with narrow wavelength ranges and offer the possibility of easily selecting the light colour. The influence of light energy varies in different processes and for different species. Efficient water movement and mixing is crucial in algae cultivation. The movement of water is crucial for algae to get exposed to light source which is the important ingredient in the photosynthesis. The continuous movement and Mixing of Algal Water will help Algal cell to get exposed to maximum light source. Algae requires few seconds of light exposure to start its photosynthetic activity. Conventional Algal circulation methods often require external energy sources or complex mechanisms like paddle wheel, centrifugal pumps etc., which consumes high power and complex structures. The chances to receive light by algae is very minimum in the old methods. This has created huge difference between the laboratory and mass scale (field) productivity. There is a need for a simple, energy-efficient system which makes algal cells to get maximum exposure to light. Various Prior experiments suggested that the small and medium scale experiments with Flat panel Photo-Bioreactors have shown that the light passing through the thin layer systems are giving higher productivity. In conventional algal cultivation systems, such as large tanks or raceway ponds, light penetration can be limited, particularly as the culture density increases. This leads to light self shading, where only the surface layers receive sufficient light, and the deeper layers are deprived of the necessary illumination, resulting in suboptimal growth rates. The higher productivity observed in the flat panel PBRs not only improves the higher output in algal cultivation but not energy efficient in the large-scale production. The thin layers also facilitate efficient gas exchange, ensuring that carbon dioxide is readily available for photosynthesis and oxygen is effectively removed, preventing oxygen accumulation that could inhibit growth. However, the present invention deals with these obstacles in order to achieve an effective cultivation system for growing the microalgae for high biomass production with low capital and operating costs. These systems are modular, scalable and economical , making them suitable for both small-scale laboratory experiments and larger industrial applications. This also helps reduce production costs, making algal products more economically viable. SUMMARY OF THE INVENTION The invention Comprises an Algal Cultivation System ( ACS ) which provides maximum light and movement of culture through artificial immersed lighting and air purging systems designed to provide uniform and continuous light for the Algae to grow continuously. The Algal culture movement is facilitated through a specially designed structure made of concrete or Plastic sheet or Fiber Glass using hydrodynamics and gravity principle. This entire structure can be stationed in the open or inside of a protected environment like green house made of Plastic or Glass or any transparent material roof to facilitate contamination free and provide environmentally safe conditions. This ACS system ensure that maximum number of algal cells gets exposed to light with minimum energy for every few minutes because of continuous multidirectional movement of algal culture through the gravity mechanism. These systems are partitioned and are made of waterproof, panels with adjustable gaps with LED lights to control light and flow of Algal culture. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1. Schematic diagram showing intracompartmental transfer of light and air in the algal culture Figure 2.System showing air distribution and light scattering Figure 3. Schematic diagrams of the water transfer system, showing the arrangement of the compartments, the gaps, and the flow of water. Figure 4. Large scale cultivation system DETAILED DESCRIPTION OF THE INVENTION This present invention explains the systems and methods for cultivation of algae in the large scale. The algae used in this system is the “Nanochloropsis Oculata” . These algae belong to the group of algae; and are one of the most widespread algae species in the Bay of Bengal in the East Coast of India. In an embodiment an algae cultivation system is provided that can include a cultivation tank, an algal liquid medium disposed within the cultivation tank, a plurality of light transmitting subsystems submerged in the liquid medium, and a plurality of air spargers. The algae cultivation system includes a cultivation tank. The cultivation tank can be filled with algal liquid medium that contains any specific species of algae. ACS is a system stationed in open or inside of an environmentally protected structure made of Metal structure with transparent roof made of plastic or Glass or any other transparent material which allows sun light to pass through it. . The centerpiece of the algae cultivation production is our newly developed algal tank with water circulation system intended for large-scale, sustainable algae production. The Algae tank used in this system is made up of concrete or plastic or reinforced plastic or any other material which makes it to erect the structure and make leak proof. The light transmitting subsystems can be configured to increase the effective light exposing surface area of the algal liquid medium, thereby increasing the ratio of illuminated surface area to total volume of the cultivation system. It is believed that increasing this ratio can contribute to enhancing the overall photosynthesis of the cultivation system. Light transmitting elements used with embodiments of the invention can be relatively simple in design and easy to clean, making the system more cost effective than many typical closed culture systems. As such, various embodiments of algae cultivation systems described herein can combine advantages normally associated with closed culture systems, such as high productivity per unit volume, with advantages normally associated with open culture systems, such as relatively low construction and operating costs. Various aspects of exemplary embodiments will now be described in greater detail. In an embodiment, a method of culturing algae can include measuring the amount of light being input into a cultivation system and mixing using air spargers will allow the liquid algal culture in multi-directional movement. “Algae Cultivation System (ACS) consists a controlled environmental conditioned system with temperature , light , Air , water circulation system, comprises of compartments to facilitate water circulation system using hydrodynamics and Gravity. Intercompartmental Lighting System (ILES) as shown in the Figure 1. and Air assisted Light Exposure System (ALES) as shown in the Figure 2 were integrated in this cultivation system which provides light when algae culture moving vertically or horizontally . The cultivation tank can have various dimensions, depending on the desired capacity of the algae cultivation system. The capacity of ACS ranges varies from 1000 litters and to many million Liters. The inner part is formed with concrete or plastic or metal (any metal) in the shape of a long, multiple rectangular compartments. The multiple compartments are interconnected with a gap between the compartments to facilitate the water algal liquid movement as shown in the Figure 3. The ACS consists of many compartments with a small gap between each compartment to allow the algal culture to flow through. All the internal compartments are interconnected with small gaps in a row or series to make them in to a single line of Algal culture flow. The Algal Culture will flow in a single way from the first compartment to the last compartment. The Algal Culture will be pumped from the last compartment through a low a head pump or air pump which requires minimum energy. The Algal Culture pumped in to the first compartment slowly moves in the second compartment through Hydrostatic pressure to maintain equilibrium and water levels because of gravity. The same Algal Culture passes through from the second compartment to the third and to the subsequent compartments till the last compartment. The same flow will be maintained till the last compartment. This flow is a continuous process till the last compartment where pumping will be done with any type or method to the first compartment. The Energy required to pump the Algal Culture is only the energy required from the last compartment to the first compartment. Because of the Gravity and Hydrostatic equilibrium enable this movement of Algal Culture to pass through all compartments one after another. In order to maintain the movement of Algal Culture and create pressure continuously the first compartment size will be bigger than the other compartments. The same size variation will be maintained till the last compartment in size with minimum differences in capacities depending on the terrain of the ACS is built as shown in the Figure 4. The pumping from the last compartment will create negative pressure on the previous compartments and this will help in increase and helps in the continuous flow of Algal Culture. A minimum of one volume of first compartment will be pumped per hour and this enables the continuous movement of algal culture in all other compartments. The topside of these compartments are open or shall be covered by a transparent material made of plastic or glass or any other transparent material. If it is covered it will protect the algal culture free from contamination form outside and allows to retain the CO2pumped to assist the photosynthesis of the algae. Benefits of this algae circulation system ( ACS) include minimal requirement for concentrated CO2supplementation, allows to retain the CO2maximum time inside the high depth culture to assist the photosynthesis of the algae. The surrounding greenhouse, also reduces energy requirements for heating and cooling, and reduces water evaporation, all while maintaining culture purity and high productivity in a modest space requirement. Every Algae cell requires less than a second light exposer which give required photons to start the photosynthesis and then starts dark reaction in the Photosynthesis activity. Traditional lighting methods in the mass cultivation are often inefficient and unable to provide light to all algal cells which led to uneven growth. There is a need for an improved mechanism lighting system to provide light to maximum number of cells that enhances the algae production through photosynthasis. Each of the cultivation systems were equipped with an artificial lighting systems fitted with RGB LEDs (LED RGBW). In the embodiment, the Algal culture movement takes place through the adjacent compartments through a gap between the compartments using hydrostatic and gravity forces. The ACS comprises a series of Algal culture compartments with gaps in between them. In these gaps ILES’s are fixed, making Algal culture to flow through this narrow gap and allows maximum number of algal cells gets light exposure between from 50 to 300 umol light intensity. Each compartment of ACS is having one ILES (Intercompartmental Light Exposure System) located in the entry and exit of the algal culture water. The ILES system is having a narrow and adjustable passage which balances by hydrodynamic gravitational movement of Algal culture water. The ILES ensures to provide light to every algal cell passing through its narrow passage as a thin layer as shown in the Figure 1. The water movement between the compartments will take place because of hydrostatic pressure from one compartment to another , make a mixed circulation of algal culture. Because of water pumping with air pumps from the last compartment negative pressure will be created because of Hydrodynamic principle in the behind compartments, which allows smoother movement of Algal culture water. The algal culture water will keep circulating horizontally inside the compartments in the entire Algal cultivation systems while giving light exposure to maximum Algal cells whenever they are crossing each compartment. As water is circulated horizontally because of air pumping and hydro dynamic gravity system the damage to the algal cells is nil when compared to the normal pumping and mechanical circulation systems. Another embodiment, in which inside of the Algae cultivation systems contain multiple ALES (Air Light Exposure Systems) made of plastic / glass transparent, non-transparent material, LED light and air assisted pumping mechanisms. The ALES of an LED light system surrounded by a transparent tube. The transparent is inside of a bigger diameter Non transparent or transparent any transparent plastic tube is made of any Plastic or Glass pipe. These tubes are fitted to a base fitted with a specially designed air delivery systems (small pipes). This air delivery mechanism is connected with an external air blower which supplies air or pressured air. The top portion of the pipe will have a plate with higher diameters which spreads the algal culture water in all directions evenly as shown in the Figure 2. In the ALES system the air pumped from the blower release through the specially made delivery system in the bottom. This air pushes the algal culture water through the narrow passage between the outer pipe and inner pipe. The Algal culture water while going up in the narrow gap will get exposed to LED light inside the transport tube and comes out and spreads all side through the top plate. The ALES system will help algal culture move vertically and get chance to get light to get photons and and CO2 from air multiple times. The CO2 in the air will get sufficient time to get dissolved in the water. This will help algal cells to do photosynthetic activity more efficiently. Each ALES is designed at least 100 % of algal water circulated horizontally and exchanged every hour in the compartment. The LED light tube will have an air dispersal unit which helps in dissipating the heat generated by LED light. The bottom part of ALES is specially designed. This part holds pipes , allows the algal water to circulate and have special system to release the air in different sizes which pushes the water upwards because of air pressure. The ACS system can be in a controlled atmosphere green house or in open sunlight. The ACS system depth can be above 2 feet (60 cm) to several meters which increases capacity by multiple times than the traditional raceway ponds. It enables the ACS system to have high volumes of Algal culture in a small foot print of area. The first and last compartments are interconnected through a pipe connected with an air assisted water pump. Water will be pumped from the last compartment through air pump inside or outside of ACS . The air assisted pumpng system water output decides the amount of time algal cell gets light exposure and the required time varies depending on the algal species. The enhanced immersion lighting systems ALES and ILES represents a significant improvement over existing algae lighting solutions and multidirectional culture movement, offering cost- effective, energy-efficient, and environmental benefits. They ensure that every algal cell gets light to do photosynthetic activity. The Algal culture while passing through ILES and ALES in the ACS system get exposure to light and air multiple times because of culture circulating in the multi directional mode . Additional CO2 supplied through nano bubbles and top light exposure and given nutrients in the algal culture water enables algae to do photosynthesis more efficiently. To achieve these benefits, this algae cultivation systems leverages several technological features: The large volume of the culture allows for high efficiency of CO2 capture while requiring a minimum amount of energy to drive mass culture circulation. The thin layer of 2cm in the ALES system also facilitate maximum light and efficient gas exchange, ensuring that carbon dioxide is readily available for photosynthesis and inhibited oxygen is effectively removed. The reactor geometry is so designed that the air bubbles flow continuously along the inner walls of ALES and constantly mixing them in the culture. The style of mixing generated by the rising bubbles closely mimics optimal algae growth conditions reproducing the cyclical pattern of light exposure that maximizes photosynthetic efficiency. The ACS is an Energy-efficient system to produce high volumes of algal culture. ACS is a simple design, easy for maintenance and can be easily scaled up. This comprehensive approach to a gravity-assisted algal cultivation system that combines advanced circulation and lighting techniques to maximize productivity and minimize costs.

Claims

We claim:

1. A system for Mass cultivation of Algae , comprising: A gravity-assisted algal culture circulation tank which comprises a series of interconnected compartments [301] arranged in the cascade mechanism utilizing hydrodynamics and gravity to enable continuous movement of the algal culture within the cultivation tank; An integrated Intercompartmental Lighting System (ILES) [101] which provides light intensity between 50 to 300 umol light to the algal water passing from one compartment to another compartment. The thickness of the water column is between 1 cm to 5 cm and this will ensure that every algal cell gets light in frequent intervals Air assisted Light Exposure System (ALES) [201] is another light providing system when the water move from bottom to top of the column and ensures maximum circulation of algal culture vertically , While water passing through the thin column between 1 to 5 cm ensure further lighting to all algal cells while moving up this vertical movement will remove the accumulated oxygen in the bottom and number of similar systems in the compartments containing a plurality of light transmitting mechanisms configured to be at least partially submerged in the algal culture medium to illuminate all the algal cells in and around the thin layer of 1 cm to 5 cm thick. This air assisted oxygen discharge system in the bottom of ALES is an unique design.

2. The system as claimed in claim 1 wherein the gravity-assisted algal culture circulation mechanism includes a series of controlled flow systems between the compartments facilitate the cross flow of algal culture under the influence of gravity and combined with hydrodynamic forces to promote circulation through ILES.

3. The system as claimed in claim 1 wherein the ILES comprises Light-emitting diodes (LEDs) strategically placed within the cultivation apparatus to provide uniform light distribution when the algal culture passes through from one compartment to another.

4. The system as claimed in claim 1 , wherein the ALES comprises air sparger positioned to give additional light in 2 cm thick while moving the algal culture upwards and maximize the absorption of CO2 and enhance its solubility into the algal culture.

5. The system as claimed in claim 1, wherein the cultivation tanks includes Gravity and air- assisted tanks designed to provide light to algal cells when passing through thin layers of algal culture, thereby improving photosynthetic efficiency.

6. The system as claimed in claim 1, wherein the gravity-assisted circulation system reduces energy consumption compared to traditional pump-based circulation systems.

7. The system as claimed in claim 1, wherein the additional lighting methods (ILES and ALES) are adjustable in terms of light spectrum and intensity to match the specific light requirements of different algal species.

8. The system as claimed in claim 1, wherein the algal cultivation system is scalable, allowing for both small-scale laboratory use and large-scale industrial production.

9. A method for cultivating algae using the system of claim 1, comprising the steps of: a) Initiating gravity-assisted circulation of the algal culture within the cultivation tank; b) Activating the ILES and ALES to provide continuous illumination and provide horizontal and vertical culture movement Dated this 18thJuly’ 2025

Images