Effect of hydraulic retention time on volatile fatty acid production and organic degradation in anaerobic digestion of palm oil mill effluent

A B S T R A C TThis work evaluated the effect of modified zeolite as microbial immobilization medium in anaerobic digestion of palm oil mill effluent (POME). The affinity of microorganisms to attach and grow on the media surface could be increased by the addition of micro-nutrient into the media. The effect of micro-nutrient addition was studied in 1000 mL Erlenmeyer flask as batch reactors. Experiments were conducted for 30 days. The concentration of soluble chemical oxygen demand (COD) in substrate was 8000 mg/L. Zeolite was impregnated with nickel (Ni) and zinc (Zn) at individual concentration of 2.7x10-3 mg Ni/g zeolite and 3.5x10‑3 mg Zn/g zeolite. The influence of each modified zeolite was determined by periodic measurement of sCOD, volatile fatty acid (VFA), pH, and biogas production. Cumulative biogas productions in this study were 252.44; 172.13; 57.70 ml from Ni-modified, Zn-modified and natural zeolites, respectively. The highest sCOD removal was obtained in reactor with Zn-modified zeolite with 38.22% removal, followed by 33.96% with Ni-modified zeolite, and 27.87% removal with natural zeolite.Keywords: anaerobic digestion; biogas; methane; palm oil mill effluent; zeoliteA B S T R A KPenelitian ini mengevaluasi pengaruh zeolit yang dimodifikasi sebagai media imobilisasi mikroorganisme pada proses anaerobik limbah palm oil mill effluent (POME). Afinitas mikroorganisme untuk melekat dan tumbuh di permukaan dapat meningkat dengan impregnasi mikronutrien pada media. Efek penambahan mikronutrien dipelajari dengan labu Erlenmeyer 1000 mL sebagai reaktor batch. Experimen dijalankan selama 30 hari. Konsentrasi soluble chemical oxygen demand (sCOD) substrat yang digunakan adalah 8000 mg/L. Zeolit terimpregnasi Ni dan Zn yang digunakan memiliki kadar 2,7 x10-3 mg Ni/g zeolit dan 3,5x10-3 mg Zn/g zeolit. Pengaruh setiap zeolit yang dimodifikasi dievaluasi dengan mengukur konsentrasi sCOD, volatile fatty acid (VFA), pH, dan produksi biogas secara periodik. Akumulasi biogas penelitian ini sebesar 252,44; 172,13; 57,70 ml berturut-turut untuk zeolit modifikasi Ni, zeolit modifikasi Zn dan zeolit alam. Penurunan sCOD terbaik dihasilkan oleh zeolit termodifikasi Zn dengan nilai 38,22%, selanjutnya diikuti oleh zeolit termodifikasi Ni dan zeolit alam dengan nilai 33,96% dan 27,87%.Kata kunci: anaerobic digestion; biogas; metana; palm oil mill effluent; zeolit

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A Techno-Economic case for Volatile Fatty Acid Production for Increased Sustainability in the Wastewater Treatment Industry

Environmental Science Water Research & Technology ◽

10.1039/d0ew00853b ◽

2021 ◽

Author(s):

Ganesh K Veluswamy ◽

Andy Ball ◽

Richard Dinsdale ◽

Alan Guwy ◽

Kalpit Shah

Keyword(s):

Wastewater Treatment ◽

Fatty Acid ◽

Anaerobic Digestion ◽

Acid Production ◽

Volatile Fatty Acid ◽

Fugitive Emissions ◽

Fatty Acid Production

Methane, the final product of methanogenesis during anaerobic digestion is a low value product (0.1$/m3). Concerns over fugitive emissions from methane coupled with recent reduction in costs of solar and...

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The Impact of Hydraulic Retention Time on the Biomethane Production from Palm Oil Mill Effluent (POME) in Two-Stage Anaerobic Fluidized Bed Reactor

International Journal of Renewable Energy Development ◽

10.14710/ijred.2021.20639 ◽

2020 ◽

Vol 10 (1) ◽

pp. 11-16

Author(s):

Laily Isna Ramadhani ◽

Sri Ismiyati Damayanti ◽

Hanifrahmawan Sudibyo ◽

Muhammad Mufti Azis ◽

Wiratni Budhijanto

Keyword(s):

Fluidized Bed ◽

Palm Oil ◽

Retention Time ◽

Hydraulic Retention Time ◽

Ph Control ◽

Palm Oil Mill Effluent ◽

Two Stage ◽

Second Stage ◽

Biomethane Production ◽

Palm Oil Mill

Indonesia is currently the most significant crude palm oil (CPO) producer in the world. In the production ofCPO, 0.7m3 of Palm Oil Mill Effluent (POME) is emitted as the wastewater for every ton of fresh fruit bunches processed in the palm oil mill.With the increasing amount of CPO production, an effective POME treatment system is urgently required to prevent severe environmental damage. The high organic content in the POME is a potential substrate forbio-methane production. The biomethane production is carried out by two groups of microbes, i.e., acidogenic and methanogenic microbes. Each group of bacteria performs optimally at different optimum conditions. To optimize the biomethane production, POME was treated sequentially by separating the acidogenic and methanogenic microbes into two stages of anaerobic fluidized bed reactors (AFBR). The steps were optimized differently according to the favorable conditions of each group of bacteria. Although perfect separation cannot be achieved, this study showed that pH control could split the domination of the bacteria, i.e., the first stage (maintained at pH 4-5) was dominated by the acidogenic microbes and the second stage (kept neutral) was governed by methanogens. In addition to the pH control, natural zeolitewas added as microbial immobilization media in the AFBR to improve the performance of the microorganisms, especially in preventing microbial wash out at short hydraulic retention time (HRT). This study was focused on the understanding of the effect of HRT on the performance of steady-state continuous AFBR. The first stage as the acidogenic reactorwas rununder acidic conditions (pH 4-5) at five different HRTs. In comparison, the second stage as the methanogenic reactorwasrun under the neutral condition at four different HRTs. In this work,short HRT (5 days) resulted in better performance in both acidogenic AFBR and methanogenic AFBR. The immobilization media was hence essential to reduce the risk of washout at such a short HRT. The two-stage system also resulted in quite a high percentage of soluble chemical oxygen demand (sCOD) removal, which was as much as 96.06%sCOD.

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