**4. Conclusion**

The temperature distribution in the steel box and the lower temperatures although reached a safe level, the time required for the safe treatment is too long and hence the steel box needs an improvement. Therefore, to efficiently reduce pathogens during the post-treatment and also reduce the time of treatment, the steel box needs an insulator to maintain the temperature. The guidelines for the design of the post-treatment facility are: For *Ascaris*, the steel box and the lower temperature −5, −10 and −15°C, post-treatment requires temperature between 78°C (maximum temperature during the day) − 6.5°C (min temperature during the night) and approximately time of 295 h to achieve the safe level of 10−4 pppy. For norovirus, posttreatment requires temperature from 78 to 6.5° and approximately time of 845 h for all the scenarios to achieve a safe level. *Salmonella* requires temperature range from 78 to 6.5°C and time of 969.5 h, for all scenarios to reach a safe level. The evaluation of the performance of post-treatment unit for risk assessment of the targeted pathogens has been achieved with the developed mathematical model.
