Automated Biodigesters: creating circular economy

Design and create a model of "automated biodigesters" using PID which could control the most important parameters in anaerobic digestion optimizing the biogas production

One common problem in the world is the big amount of organic waste that is produced each day. It is more notorious in some rural cities, for example Chulucanas, Morropón, Sullana and others provinces of my dear Piura where 31% of economically active population works in agriculture according to a news from the DRP (Regional Directorate of Production of Piura in spanish).The solution have already been proposed: the biodigester. It is a device that, taking advantages of the natural anaerobic digestion, transform organic waste in methane (biofuel) and biol (nutrient-rich liquid fertilizer).

Nevertheless, it is hard to control some metrics inside it like the pH which have to be in a short range, the high temperatures necesary for the process and other conditions necessary conditions to control the amount of microorganisms for the digestion and methane production. When one of this metrics is out of range the process suffers an inhibition and the products of anaerobic digestion are not as good as expected.

It is the problem my team wants to solve: to desgin a system of a biodigester and create a PID system in order to control most of the valuable parameters in the process. If the process turn on automatic, the process would be optimized generating the maximum amount posible of methane. As a result, the whole benefits of biodigesters as reduction of greenhouse gas emissions, generation of renewable energy, reduction of waste, odor control in cropland (due to animal waste) would became a feasible reality.

In sample terms, the automatic biodigester works with a serie of sensors that take the measures of the most relevant parameters in the process like pH, temperature, microorganism population and volumetric gas production, compare the actual value of each one with their respective suitable and uses actuators to decrease the error. For example, if the temperature gets lower than 35°C, use a heater so the process doesn't decrease the velocity of methane production, in case of a desviation in pH the system turn on a pump that could add an organic solution acid or alkaline depending of wath it needs. 

In long term we plan to experiment with different compositions of biomass and uses neural networks with the objective of finding the best type of organic waste to produce methane making the biogas generation more efficient.

The idea’s beginning was in a conference of an engineer doctor that presents to us some projects with high potential in the region. After that we talk to him and talk to us that there were many biodigesters in the country but the main problem they had was that the parameters sometimes vary and the manual control didn’t control very well. Since there my team and me started to look for information in books, papers and magazines related to the process. We even found a thesis where we notice that the cocoa shell should produce a better biogas with higher percentage of methane so we though that  it could be very useful here in the region because the cocoa is one of most grown fruit here in the region. Even one member of the team commented that effectively his family has some cocoa plants and he have seen that the shell never always was thrown in the earth. We think to star with that agricultures.

We are students of the University of Piura, UDEP, and we have experience in help-works in the agricultural sector because we have learned in the laboratories of Control and Automation Systems. Te have more than a year woking like a team and seeing the development of proyects, also we have participate in volunteering in our University and some members have family in the countryside that can benefit with this solve and enhance the productivity in the region.

We have seeing bibligraphic references, and consult different experts and them told us that is an area with a lot of potencial in the region.

There are some proyects in this sector but in a little scale and we want to optimize this for benefit more people in this sector beacuse this is one of the most importat activities in our country but them dont have the optimal conditions of developing.

Have at least 3 the automatize biodigestors systems in the main provincis of our regions.

Our idea is based on the use of a PLC which has a hardware that controls the motors and read the metrics. Also the process and its main parameter could be watched in any desktop using a software that we will develop for monitoring. Our solution includes some technology like hyperspectral camera and high precision sensors

About he 5% of the agricultural sector in Piura

The lack of sensors that can be a lot of help, like the multispectral cameras.

Also the Testing to find the values od the PID programming on a PLC, and the classify of the organic material to testing their methane productivity.