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Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 223
Author(s):  
Erlon Lopes Pereira ◽  
Alisson Carraro Borges ◽  
Greicelene Jesus da Silva

The wastewater from the biodiesel industry is an environmental problem, and from a sanitation resources perspective, the anaerobic sequencing batch reactor (ASBR) is an interesting alternative for wastewater treatment. A better understanding of ASBR operation behavior under the progressive increase of the organic loading rate (OLR) is crucial for upscaling. The objective of this study was to monitor an ASBR operating with an OLR ranging from 1.3 to 9.3 kgCOD m−3 d−1. The average chemical oxygen demand (COD) removal efficiencies of the ASBR were 52, 41, 47, and 11% for phases 1, 2, 3, and 4, respectively. The apparent kinetic coefficient, i.e., the rate of degradation of organic matter, was between 0.10 and 1.80 h−1, considering the kinetic model that considers the residual substrate concentration, which was the one that best fit the obtained data. The progressive increase in applied OLR modified the microbial biomass diversity, which in turn influenced the degradation kinetics of the organic matter. In addition, the values of the applied OLR of 5.1 kgCOD m−3 d−1 and a food to microorganism ratio (F/M) of 0.6 kgCOD kgVSS−1 d−1 were shown to be limiting values that promoted the overload of ASBR.


2021 ◽  
Vol 9 ◽  
Author(s):  
Karin Ahlberg-Eliasson ◽  
Maria Westerholm ◽  
Simon Isaksson ◽  
Anna Schnürer

Biogas production from manure is of particular value in regard of lowering greenhouse gas emissions and enhancing nutrient re-circulation. However, the relatively low energy content and the characteristics of manure often result in low degradation efficiency, and the development of operating strategies is required to improve the biogas yield and the economic benefits. In this study, the potential to enhance the performance of two full-scale biogas plants operating with cattle manure, in mono-digestion or combined with poultry manure, was investigated. Four continuously fed laboratory-scale reactors were operated in sets of two, in which the temperature in one reactor in each set was increased from 37–42°C to 52°C. The potential to increase the capacity was thereafter assessed by increasing the organic loading rate (OLR), from ca 3 to 5 kg volatile solids (VS)/ m3 and day. The processes were evaluated with both chemical and microbiological parameters, and in addition, the residual methane potential (RMP) was measured to evaluate the risk of increased methane emissions from the digestate. The results showed that both processes could be changed from mesophilic to themophilic temperature without major problems and with a similar shift in the microbial community profile to a typical thermophilic community, e.g., an increase in the relative abundance of the phylum Firmicutes. However, the temperature increase in the reactor co-digesting cattle and poultry manure caused a slight accumulation of fatty acids (2 g/l) and reduced the specific methane production, most likely due to ammonia inhibition (0.4–0.7 g NH3/l). Still, during operation at higher OLR, thermophilic as compared to mesophilic temperature slightly increased the methane yield and specific methane production, in both investigated processes. However, the higher OLR decreased the overall degree of degradation in all processes, and this showed a positive correlation with increased RMP values. Chemical analyses suggested that high RMP values (40–98 Nml gVS−1) were related to the degradation of cellulose, hemicellulose, and volatile fatty acid enriched in the digestate. Conclusively, increased temperature and load can increase the methane yield from manure but can result in less efficient degradation and increased risks for methane emissions during storage and handling of the digestate.


2021 ◽  
Vol 232 (12) ◽  
Author(s):  
Vinicius Masquetti da Conceição ◽  
Eloisa Pozzi ◽  
Isabel Kimiko Sakamoto ◽  
Fabricio Motteran ◽  
Eduardo Cleto Pires

Author(s):  
Nithya Gopinath ◽  
Madhu G. ◽  
Joseph Francis

In this study, wastewater from a centrifuge rubber latex concentration unit was experimentally treated by an up-flow anaerobic filter (UAF) at variable hydraulic detention time to investigate the COD removal efficiency and the gas production rate. The UAF reactors were made of PVC pipe with an inside diameter of 9.5 cm, 180 cm in height, with a bed volume of 12.8 L, and filled with polyethylene media. The initial COD concentration of wastewater was in the range 4620 - 10400 mg.L-1. HRTs were controlled at 20 days, with the organic loading rate varying from 2.9 to 10.5 kg.day.m-3. The findings show that the COD removal efficiency of the system was in the range of 85% to 92% for the varying organic loading rates. In addition, the specific methane production rate varied from 8.2 to 14 L of CH4 produced/g of COD destroyed/day for the different organic loading rates.


2021 ◽  
Vol 342 ◽  
pp. 125920
Author(s):  
Mukesh Kumar Awasthi ◽  
Steven Wainaina ◽  
Amir Mahboubi ◽  
Zengqiang Zhang ◽  
Mohammad J. Taherzadeh

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