Pengaruh Kadar Air Umpan dan Rasio C/N pada Produksi Biogas dari Sampah Organik Pasar

https://doi.org/10.22146/jrekpros.24526

Zuliyana(1*), Sang Kompiang Wirawan(2), Wiratni Budhijanto(3), Rochim Bakti Cahyono(4)

(1) 
(2) 
(3) 
(4) 
(*) Corresponding Author

Abstract


Nowadays, Indonesia is facing serious problem related to the rapid generation of municipal solid waste (MSW) and dependence on fossil energy. Converting organic content of MSW into biogas through biological process by mean of anaerobic digester is one of promising proposals to solve the MSW problem. In order to optimize biogas production, this research studies the effect of Total Solid (TS) content and ratio of carbon to nitrogen (C/N) within organic fraction of MSW as raw material for biogas production. The organic fraction of MSW consists of vegetables and fruits waste which originated from traditional market.
The experiments using various TS concentrations (10%, 15% and 20%) were conducted in batch reactors. The results showed that TS content of MSW raw material had significant effects on the total volume and CH4 concentration of biogas production. High water content in MSW raw material enhanced the hydrolysis of organic fraction as well as avoided the excessive Volatile Fatty Acid (VFA) concentration which posed the risk of inhibition on the anaerobic process. Based on the results, the TS concentration of 10-15% in the organic MSW would offer an optimum yield of biogas production. In order to examine the effect of C/N ratio, the organic MSW was modified using ZA fertilizer (36, 30, 20 and 10 C/N ratios). The C/N ratios of 20-30 produced high amount biogas and CH4 concentration compared to others. The C/N ratio should be maintained at the optimum value to prevent the accumulation of free ammonia which could cause problems in the anaerobic process.
Based on the results, the biogas production from organic MSW would yield the optimum biogas amount and CH4 concentration when the TS concentration and C/N ratio were 10-15% and 20-30, respectively. This outcome would give recommendation on the water addition to the raw organic fraction of MSW and C/N modification when converting the organic fraction of MSW to biogas.

Keywords: biogas, C/N ratio, municipal solid waste, total solid.

Permasalahan sampah dan ketergantungan akan energi fosil mendorong pemanfaatan sampah organik menjadi biogas. Penelitian ini dilakukan untuk mempelajari pengaruh konsentrasi Total Solid (TS) dan rasio C/N dari sampah kota sebagai bahan baku produksi biogas. Sampah kota berupa sayuran dan buah yang merupakan fraksi organik yang diperoleh dari pasar tradisional dan selanjutnya produksi biogas dilakukan dalam reaktor batch.
Konsentrasi TS bahan baku divariasikan menjadi tiga variasi nilai TS yaitu 20%, 15% dan 10%. Konsentrasi TS pada bahan baku digester berpengaruh secara signifikan terhadap jumlah akumulatif biogas yang dihasilkan dan kadar CH4. Diperlukan air dengan jumlah yang optimum untuk mempercepat proses hidrolisis sekaligus mencegah konsentrasi Volatile Fatty Acid (VFA) terlalu tinggi yang beresiko inhibitor dalam sistem anaerob. Pada penelitian ini, untuk jenis sampah sayur/buah, nilai TS yang relatif baik adalah antara 10-15%. Modifikasi nilai rasio karbon terhadap nitrogen (C/N) dilakukan pada bahan baku dengan kadar TS optimum dimana nilai rasio C/N dimodifikasi menjadi 36 (rasio C/N orisinal TS optimum), 30, 20 dan 10. C/N ratio yang lebih rendah daripada nilai orisinalnya dicapai dengan penambahan pupuk ZA. Dalam penelitian ini, rasio C/N antara 20-30 memberikan hasil yang relatif paling baik dibandingkan nilai rasio C/N yang lain. Perlu dijaga agar nilai rasio C/N tidak terlalu rendah yang menyebabkan kinerja sistem anaerob justru lebih buruk. karena akumulasi ammonia bebas yang justru merupakan inhibitor.
Berdasarkan hasil yang diperoleh, produksi biogas dari sampah buah dan sayur menunjukkan hasil yang optimum saat kisaran konsentrasi TS 10-15% dan rasio C/N 20-30. Hal ini memberikan rekomendasi jumlah penambahan air dan perlu tidaknya koreksi rasio C/N pada umpan bahan baku saat operasi skala industri.

Kata kunci: biogas, rasio C/N, sampah kota, total solid.


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DOI: https://doi.org/10.22146/jrekpros.24526

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