ANAEROBIC CO-DIGESTION OF SOLID WASTE FROM COFFEE BENEFIT, BANANA PSEUDO-STEM AND PIG MANURE: KINETIC, ENERGY AND ENVIRONMENTAL CRITERIA

Abstract

Introduction:
Anaerobic co-digestion promotes the dilution of toxic substances and improves the balance of nutrients in the process, which could increase the production of methane from solid waste from coffee processing (C). The pseudo-stem of banana (Bps) and pig manure (Pm) are two possible co-substrates produced in Ecuadorian agricultural sector. 
Objective:
To evaluate the co-digestion of solid waste from coffee processing with banana pseudostem and pig manure in terms of methane production, energy potential and reduction of emissions.
Materials and Methods:
The first order and Chapman expressions were the models for evaluating the methane potential and the kinetics of the process. Likewise, the mixing effects evaluation was through the practical criteria φy, φk, and φtGrenz. The selected criteria for evaluating the feasibility of the proposals were: (i) avoided greenhouse gas emissions and (ii) gross energy.
Results and Discussion:
The binary mixture with Bps increased the methane yield of solid coffee residues up to 317 NmLCH4/gVS. Likewise, the results of the anaerobic co-digestion of C+Pm indicated a gross energy production of 1514 kJ/1000 kg of treated waste.
Conclusions:
The methane yield in the digestion of solid residues from coffee benefit was lower compared to the mixtures evaluated. The C+Pm mixture presents the greatest potential for reducing GHG emissions and energy production.