Team:SDSZ China/pf

iGem SDSZ_China 2018

Product flow

1.over view

The automatic machine we designed is composed of six units. To successfully obtain industry applicable chitosan from lobster shells, the first basic part of the processing system is designed to be the purification of chitin from highly crystalized shells. We have invented five processing units that are assembled to achieve this goal. The steps are the pretreatment of raw materials, the reaction with sodium hydroxide to remove protein, rinsing, and eliminating minerals. After obtaining purified chitin, the most crucial step comes to the transformation process from chitin to chitosan through a specially designed container filled with effective enzymes that we synthesized.

2.The Procedures involved

1). The Pretreatment of materials

Large scale of industrial production requires storage system of raw materials that ensures both the stable quality of reactants and the convenient applicability of them for further treatments.
In our design, the first unit of the machine functions to eliminate physical impurities mixed in the raw materials and as a container of the treated materials.
The storing compartment mentioned above is installed with an electric fan, heating device and a discharge gate.
When the raw materials are placed on top of a filter screen and put into the container, sodium hydroxide inside would actively react with the impurities and rinse them off the lobster shells. These impurities can be brought away and discarded through the discharge gate, leaving the roughly purified lobster shells inside the compartment above the filter screen, which can be lifted and transferred to the second reaction tank of the mechanical system.
Thus, the pretreatment and storage of raw materials can be achieved through rinsing in alkali and constant drying. The automatic design greatly eliminates the need of operators involved in the process, and thus reduces the possibility of the occurrence of safety accidents on laborers.

2). Remove protein.

Overview

In order to obtain highly purified chitin from crystalized lobster shells, it is necessary to remove the protein inside the shells, which can ensure high efficiency of transformation from chitin to chitosan. We have designed a set of biological reaction tanks to allow the reaction take place efficiently in the most time and energy saving method. Reaction Theory

The whole process of the reaction takes place inside three adjacent reaction tanks A, B, and C. According to experiment data and relevant scientific journals, the removal of protein inside crabs and lobsters’ shells requires continuous reaction with alkali. It is documented that the alkali solution needs to be replaced after a 24-hour reaction to ensure producibility and efficiency, after which the lobster shells still need to be in contact with newly added solution for complete 12 hours without heating or 4 hours with heating to undergo the complete removal of protein. It is applied in industrial production that the solid sediment abstracted from the remains of the reaction can be used as fertilizers, while the liquid supernatant of the deposited reaction system can be reused for another round of reaction with lobster shells. By analyzing and synthesizing useful information, we gained inspiration and successfully designed a new reaction system that significantly reduces total reaction time and better utilizes the reaction tanks as well as the reactants. Product Design

As shown in the figure above, the reaction tank is composed of chamber A, B, and C in which lobster shells can fully get in contact with sodium hydroxide solution. All chambers are equipped with timers and transport units while one of the chambers is equipped with a heater.
A specially designed time regulation design shown in the graph below ensures that each chamber has the least amount of time staying unoccupied, and thus improving the reaction efficiency and saving energy, since only chamber B needs to be heated throughout the complete round of reaction. The traditional time for one fixed amount of materials to transform completely is seventy-two hours per unit while using our new plan, we simply need fifty-four hours per unit and can increase the efficiency by 33%.
After filling all of the chambers with low concentrated alkali solution, the reaction cycle starts. When one round of 24-hour reaction is completed inside chamber A or C, the lobster shells are abstracted from the chamber and put into chamber B through the control of timers and transport units. The materials react inside chamber B for a heated reaction of 4 hours or a non-heated reaction for 12 hours. The leftover of the reaction inside chamber A and C are provided time to fully deposit, and the sediments are extracted after a 12-hour deposition as chemical fertilizer while the liquid supernatant remains inside the tanks to react with a new round of lobster shells. Meanwhile, when the transformation inside chamber B is finished, the products of the reaction are abstracted and transferred into the next unit of the machine while the leftover of the reaction keeps on depositing for 8 or 12 hours (depending on if the former reaction is heated) until solid sediment can be fully set apart and abstracted from the liquid supernatant.
Improvement

The calculated and specially designed time control system of the reaction indicates higher efficiency of the reaction by increasing the utilization of each reaction tank in a given amount of time. The deposition of reactants not only increases the utility of all products and by-products of the reaction, but also helps reduce the overuse and emission of alkali solution. The process protects natural water body. Energy consumption is decreased in that only one of the three tanks needs to be heated discontinuously during the complete process of the reaction, and the amount of safety accidents caused by wrong operation while heating is consequently reduced to the least.