BAU-STR Dryer: An Efficient Technological Solution for Reducing Post- Harvest Loss

BAU-STR Dryer: An Efficient Technological Solution for Reducing Post- Harvest Loss

By Chayan Kumer Saha and Md. Monjurul Alam

Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Email: cksaha(at)bau.edu.bd; mmalam.bau(at)gmail.com

Drying of paddy is an essential post-harvest operation before storing and processing of paddy. Poor or defective drying facilities or incorrect drying procedures may result in very fast drying rates, incomplete drying, moisture re-absorption and uneven moisture distribution within the grain mass. Improper drying results in high costs/storage loss, low efficiencies, high milling losses and poor quality of milled rice. Deterioration of paddy is accelerated when it is stored with high grain moisture content or is exposed to wet or high relative humidity conditions. Unless the grain is dried immediately and stored properly after harvest, losses are likely to be incurred at the pre-milling and milling stages. A grain dryer is a solution for the problems and can be evaluated properly only after reliable tests have been performed.

Sun drying is the traditional drying practice in Bangladesh. In sun drying, farmers leave their harvested paddy on the field, yard or concrete floor for a long time and the paddy is dried with the help of sun’s heat. It is a time-consuming process and it also depends on the weather conditions. Sudden changes in weather such as rain and foggy weather hamper the sun-drying process. These result in delayed drying, re-wetted grains and quality deterioration which cause damage in grain and reduce the quality and market value of grain. Therefore, alternate drying practices such as mechanical drying need to be adapted in Bangladesh to improve the drying performance.

An economical hot air circulated dryer was developed at Bangladesh Agricultural University, sponsored by USAID and the ADM Institute for the Prevention of Postharvest Loss sponsored the project entitled “Post-Harvest Loss Reduction Innovation Lab-Bangladesh” for rapid and efficient drying. This dryer is called BAU-STR dryer. The original STR dryer was a Vietnamese low-cost dryer developed by Centre for Agricultural Energy and Machinery, Long Nam University, Vietnam and Japan International Research Centre for Agricultural Sciences (JIRCAS). The same working principle of STR was used for developing the BAU-STR dryer using locally available materials in a sustainable manner for farmers and small traders.

The BAU-STR dryer consists of two cylinders (inner bin, outer bin), blower, hot air pipe, burner, bamboo, polythin sheets and rope. Outer and inner bins are stainless steel (SS) wire mesh (8 mesh). These cylinders are designed in such a way so that paddy or small grains can be properly placed into the annular space of the cylinders. Inner bin is fixed but outer bin can be adjusted for drying 300 to 500 kg per batch depending on the availability of grain for drying. The optimal setting of outer bin is for holding 500 kg of paddy. Rice husk briquettes are used as fuel. An axial Vietnamese blower was used initially to suck the hot air. Later, a blower has been developed by Post-Harvest Loss Innovation Lab (PHLIL)-Bangladesh using locally available material. The modified blower’s performance is similar to the Vietnamese blower. The function of the blower is to suck the hot air and push the hot air into the perforated cylinders evenly. The blower is powered by a 1 hp electrical motor. A hot air pipe is used for conveying the hot air which is generated by a burner. A temperature monitor meter has been added to continuously monitor temperature reading of grain, as high temperature or rapid drying reduces germination rate of seeds and milling yields, since cracks will develop.

LPG heating system-based BAU-STR Dryer schematic

A photo of the LPG heating system-based BAU-STR Dryer in use.

Several studies were done on BAU-STR dryer considering different seasons, different drying capacity, different verities, etc. BAU-STR dryer can dry the paddy within a very short period of time, i.e. in 3 to 5 hours depending on the initial moisture content. The moisture removal rate for each treatment was almost similar, around 2% mc per hr. The satisfactory germination rate and milling quality was found in BAU-STR dried paddy. In the primary stage, rice husk briquette was used as heat source. But, briquette burning capacity depends on moisture content and briquette quality. During the drying process, briquettes need to be fed frequently (every 5 minutes) in the dryer. However, briquettes are not available all over the country. Therefore, liquefied petroleum gas (LPG), a clean source for cooking and available all over Bangladesh, was considered as a heat source unit. An LPG-based heating system was developed for BAU-STR dryer using locally available materials, and drying efficiency was found better than the rice husk briquette-based heating system. LPG does not need to be refilled repeatedly during drying. Recently, LPG with a locally developed blower is found to be a better alternative than rice husk briquette as a heating source in BAU-STR dryer considering drying efficiency, germination percentage (above 90%) and milling recovery (around 75%). The operating cost and payback period of LPG-based BAU-STR dryer are 0.89 BDT per kg and less than one year, respectively. The post-harvest drying loss can be saved 2.5 to 4% in comparison to traditional sun drying method. The BAU-STR dryer using LPG as a clean heating source with locally manufactured blower would be the best option for the farmers, seed producers and small traders in Bangladesh as well as other rice-producing developing nations in the world.

43 Comments

  • Moovendhan Posted September 26, 2020 1:00 am

    I need this model to my village please send the details to mine moovend.s@gmail.com

    Reply
    • Sarah Schwartz Posted October 1, 2020 2:22 pm

      Thank you for your interest in the BAU-STR dryer. We have sent you an email with further details. Best, ADMI.

      Reply
      • Abu Haq Posted September 15, 2022 4:31 pm

        Need details on purchasing 3-4 units of this.

        Reply
        • Sarah Schwartz Posted February 28, 2023 3:22 pm

          Please check your email for a response to your request. Best wishes.

          Reply
      • Ajaykumar Goudar Posted July 15, 2023 11:28 pm

        I need oe such dryer in my place pls send me details

        Reply
        • Leslie Myrick Posted August 16, 2023 1:54 pm

          Hi thanks for your interest. Please check your email for more information.

          Reply
  • Engr.Md.Quamruzzaman Posted October 30, 2020 12:40 am

    29.10.2020
    We,four teachers from Govt. Technical School and College from Bangladesh had an opportunity to visit the lab and knew about the BAU-STR Dryer. Our favorite teacher Professor Dr. Monjurul Alom Sir explained the different aspects of the dryer. We do belive that this dryer may be an excellent innovation to minimise the post harvest loss of grain crops . We wish the success of this dryer which may be popular nationwide very soon. Thanks a lot to our favorite teacher and all concerned people related to this innovation.

    Reply
  • MD NAJMUS SAKIB RAZIN Posted April 29, 2021 5:10 pm

    From where I can buy this dryer?
    please let me know if possible through my email: nsrazin2357@gmail.com

    Reply
    • Sarah Schwartz Posted June 4, 2021 3:35 pm

      Thank you for your interest. We have responded to you at the email address provided.

      Reply
  • Akin Posted August 11, 2021 4:42 pm

    Hello, please could you give the dimensions of the two cylindrical meshes? Also, could this set up be used to dry corn on the cob? I would be glad to receive further help. Thanks.

    Reply
    • Sarah Schwartz Posted July 5, 2022 1:51 pm

      Hello, detailed information has been sent to you at the email address provided. Thanks!

      Reply
      • Dew Abyslo Posted February 5, 2024 3:58 pm

        Please,provide us with the dimensions and power of the blower,inner and our bins,hot air pipe,burner type and maximum paddy that this dryer may be used to dry?

        Reply
        • Leslie Myrick Posted February 28, 2024 1:18 pm

          We just sent an email with more info.

          Reply
  • Leon4570 Posted October 9, 2021 8:56 pm

    Where can we access this dryer in the philippines?

    Reply
  • Rico rommel varquez Posted October 19, 2021 11:16 pm

    Should you trust me please send me the details of the design.it is highly recommended for small scale farmers like me.thank you for sharing and godbless

    Reply
    • Sarah Schwartz Posted July 5, 2022 1:48 pm

      Hello, detailed information has been sent to you at the email address provided. Thanks!

      Reply
  • Rick Olson Posted June 14, 2022 4:57 pm

    I would like to have complete plans for building this rice dryer. A biologist colleague of mine is doing some experiments growing a modest amount of rice (several acres), in the Columbus, Ohio USA area, and I am supporting him doing mechanical engineering work. Sun drying is not an option in the late fall in Ohio.

    Reply
    • Sarah Schwartz Posted July 5, 2022 1:47 pm

      Hello, detailed information has been sent to you at the email address provided. Thanks!

      Reply
      • Abdulmalik Posted December 7, 2022 4:23 am

        How about sending it here Ma’am? aabdulmalik255@gmail.com

        Reply
        • Sarah Schwartz Posted February 28, 2023 3:11 pm

          Please check your email for a response to your request. Best wishes.

          Reply
  • Daniel Carter Posted June 29, 2022 12:49 am

    Can you send me the plans please

    Reply
    • Sarah Schwartz Posted July 5, 2022 1:46 pm

      Hello, detailed information has been sent to you at the email address provided. Thanks!

      Reply
  • Daniel Grall Posted August 23, 2022 10:49 am

    Hello, I would like to build this dryer in the Philippines for our small farm. Can you send us some detailed plans ?
    Thank you very much.

    Reply
    • Sarah Schwartz Posted February 28, 2023 3:25 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Janus Posted September 6, 2022 10:52 pm

    Good day. This design is convincing. Can I kindly ask for these plans, along with any resulting data from its operation if possible? Thank you.

    Reply
    • Sarah Schwartz Posted February 28, 2023 3:24 pm

      Please check your email for a response to your request. Best wishes.

      Reply
      • Chee Posted October 20, 2023 1:55 am

        Where can we purchase a unit?

        Reply
        • Leslie Myrick Posted October 25, 2023 10:22 am

          Thanks for your interest. We will send you an email with more details.

          Reply
  • Niel Cadaps Posted November 2, 2022 7:54 am

    Hi, would you please send me the detailed plan for this type of dryer. our community might benefit greatly from this dryer.

    Reply
    • Sarah Schwartz Posted February 28, 2023 3:21 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Antonio Magnanao Posted December 2, 2022 5:59 pm

    Can you please give detailed information and construction of this BAU rice dryer

    Reply
    • Sarah Schwartz Posted February 28, 2023 3:20 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Eric Akyea-Mensah, Director, Agraria Ltd Posted December 9, 2022 4:44 am

    Hi Sarah, we are also very interested in the BAU – STR dryer..please send us more information..best regards Eric

    Reply
    • Sarah Schwartz Posted February 28, 2023 3:15 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Bruno Villanueva Posted February 28, 2023 11:33 am

    Me puedes enviar los planos por favor, queremos utilizar el secador para achiote en Mexico

    Reply
    • Sarah Schwartz Posted February 28, 2023 3:19 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Sam Satin Posted March 28, 2023 12:57 am

    Hi, can you please send me more information on this – 2 units to start with.

    Reply
    • Sarah Schwartz Posted June 14, 2023 2:03 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Musharuf Ahmed Posted April 1, 2023 3:40 am

    I want to buy this dryer

    Reply
    • Sarah Schwartz Posted June 14, 2023 2:04 pm

      Please check your email for a response to your request. Best wishes.

      Reply
  • Md Mamunur Reza Posted November 14, 2023 10:12 pm

    Please send full 1 set Specifications of the STR dryer

    Reply
  • Said C Posted December 18, 2023 8:57 am

    Please, could you send me a full specifications of the dryer?

    Reply
  • Naveen REDDY Posted December 24, 2023 12:26 pm

    Could you mention the price of 1 unit my mail I’d is naveenkumar1978@rocketmail.com

    Reply

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