The role of pH in the organic material solubilization of domestic sludge in anaerobic digestion

2003 ◽  
Vol 48 (3) ◽  
pp. 143-150 ◽  
Author(s):  
C. Yangin Gomec ◽  
R.E. Speece
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Ph Control ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Soluble Chemical Oxygen Demand ◽  
Ph Controlled

The effect of pH on anaerobic solubilization of domestic primary sludge and activated sludge was investigated and compared. Anaerobic solubilization was carried out in continuously stirred anaerobic reactors at mesophilic temperature (35°C) and pH was fixed at 6.5 (pH-controlled). Many researches reported the serious effects of pH on the solubilization of organic materials. Thus, the aim of pH control in the reactors consisting of domestic primary and activated sludges, was the evaluation of retardation in hydrolysis/acidogenesis at low pH values. Since primary and activated sludges have different biodegradation characteristics, results were compared. Results indicated that the destruction of Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) were better in the pH-controlled reactors. In both sludges, acetic acid was the main Volatile Fatty Acid (VFA) produced. In the pH-controlled reactors, VSS reduction was found to be 72% in about 20 days in the anaerobic digestion of activated sludge, whereas for the same interval VSS reduction could only be achieved by 32% in primary sludge at 35°C. When primary sludge was used as substrate, the pH-uncontrolled and the pH-controlled reactors removed VSS with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). However, production of VFAs and SCOD was ceased after 5 days in the pH-controlled reactor whereas VFAs and SCOD production continued after 5 days in the pH-uncontrolled reactor, which indicated that hydrolysis and fermentation did not complete and continued longer. On the other hand; in either the pH-uncontrolled or the pH-controlled reactor of activated sludge, VSS was not removed with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). It was apparent that solubilization was occurring, however this solubilization was not observed as VFA production. When total methane production and total COD (CODtot) removal were estimated using VSS removal in both types of sludges, results indicated that pH control enhanced biogas productions as well as CODtot removals.

Organic material solubilization of domestic primary sludge in anaerobic digestion at controlled pH

2003 ◽  
Vol 48 (4) ◽  
pp. 195-198 ◽  
Author(s):  
C. Yangin Gomec ◽  
R.E. Speece
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Ph Influence ◽  
Soluble Organic Carbon ◽  
Soluble Chemical Oxygen Demand ◽  
Ph Controlled

The role of the pH in the anaerobic digestion of domestic primary sludge at mesophilic temperature was evaluated. Since solubilization of organic materials is seriously affected by pH, much research has been performed for the evaluation of significant pH influence on the production of soluble organic carbon in the acid phase. In this study, the performance of continuously stirred anaerobic reactors for the production of soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFAs) in domestic primary sludge was investigated. In the first anaerobic reactor, the pH was not controlled (pH-uncontrolled) whereas the pH was fixed at 6.5 (pH-controlled) in the second reactor. Two sets were performed. Results of both sets indicated that, VSS was removed with a corresponding production of VFAs and SCOD in both reactors. However, production of VFAs and SCOD stopped earlier in the pH-controlled reactors. Methanogenic phase started to operate at earlier times whereas hydrolysis and fermentation were still operating in the pH-uncontrolled reactors. The process stability and efficiency of anaerobic digestion of substrates such as domestic primary sludge can be improved by anaerobic digestion elutriated phased treatment (ADEPT) in which the acid elutriation reactor and methanogenic reactor are separated. In this respect, ADEPT was introduced.

scholarly journals Evaluation of acidogenic sludge from anaerobic reactors running at low solids retention times to reduce sludge generation and enhance biogas production

Water SA ◽  
2019 ◽  
Vol 45 (4 October) ◽  
Author(s):  
Wilza Da Silva Lopes ◽  
Ysa Helena Diniz Morais de Luna ◽  
Jose Tavares de Sousa ◽  
Wilton Silva Lopes ◽  
Valderi Duarte Leite
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Kinetic Constant ◽  
Oxygen Demand ◽  
Gas Production ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Solids Retention ◽  
Improved Performance ◽  
Pre Treatment

ABSTRACT   Sludges generated in the biological processing of sewage are complex mixtures, the constituents of which pose risks to public health and the environment. Anaerobic digestion is considered the most sustainable option for treating sludge because it offers the possibility of generating biogas. The aim of this study was to compare the quantities, properties, biodegradabilities and biochemical methane potentials (BMP) of primary sludge (PS) generated by a primary decanter with acidogenic sludges produced by upflow anaerobic (UA) reactors operating at solids retention times (SRTs) of 2, 4, 6 and 8 days (Samples S2, S4, S6 and S8, respectively). Sludges from both pre-treatments were submitted to alkaline solubilization in order to determine the efficiency of the process in disrupting extracellular complexes. Based on the levels of total solids (TS) present, the primary decanter was found to generate higher quantities of excess sludge (yield of 3.1 gTS∙d-1) than UA reactors operating at low SRTs (yields in the range 1.69 to 0.64 gTS∙d-1). The concentrations of dissolved materials in PS and Samples S2 and S8 were considerably higher after alkaline solubilization, with respective increases of 8, 14 and 28-fold in dissolved organic carbon, 12, 20 and 40-fold in chemical oxygen demand, 25, 31 and 59-fold in proteins, and 17, 21 and 63-fold in carbohydrates. In addition, the BMP value for S8 was some 13% higher than that recorded for PS while the kinetic constant for gas production by S8 was 1.8-fold greater than that of PS. It is concluded that a pre-treatment combining anaerobic digestion at low SRT and alkaline solubilisation would lead to improved performance in subsequent stages of anaerobic digestion and, consequently, increased efficiency in biogas production.

Riboflavin boosts fermentative valeric acid generation from waste activated sludge

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3962-3969
Author(s):  
Binfang Shi ◽  
Jingang Huang ◽  
Zhenjiang Yin ◽  
Wei Han ◽  
Shanshan Qiu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Acid Production ◽  
Volatile Fatty Acids ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Valeric Acid ◽  
Waste Activated Sludge ◽  
Acid Generation

Fermentative valeric acid production is a promising way to recycle valuable resources from waste activated sludge (WAS). This study investigated the feasibility of using riboflavin (RF) to enhance volatile fatty acids (VFAs) production, especially valeric acid production from WAS coupled with solid reduction. The results indicated that RF (0.5 mM) promoted the VFAs production by up to 41.0%. Valeric acid accounted for the most abundance within the VFAs components. When RF dosages were 0.05 to 5.0 mM in the WAS fermentation systems, the chemical oxygen demand fractions of valeric acid to the total VFAs were 41.0% to 62.8%, which were much higher than those using other chemical supplements. Moreover, RF enhanced the reduction of mixed liquor volatile suspended solids (MLVSS). When RF dosage was 0.2 mM, MLVSS reduction achieved a maximum at 47.4%, compared to that in the RF-free control (33.9% reduction). Riboflavin in this study was considered as a feasible chemical to enhance the fermentative valeric acid generation coupled to MLVSS reduction, realizing the reduction of solids and the reutilization of valuable resources from WAS.

scholarly journals Process Optimization of Waste Activated Sludge in Anaerobic Digestion and Biogas Production by Electrochemical Pre-Treatment Using Ruthenium Oxide Coated Titanium Electrodes

2021 ◽  
Vol 13 (9) ◽  
pp. 4874
Author(s):  
Gan Chin Heng ◽  
Mohamed Hasnain Isa ◽  
Serene Sow Mun Lock ◽  
Choon Aun Ng
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Ruthenium Oxide ◽  
Parameters Optimization ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
Pre Treatment

Anaerobic digestion (AD) appears to be a popular unit operation in wastewater treatment plant to treat waste activated sludge (WAS) and the produced methane gas can be harvested as renewable energy. However, WAS could inhibit hydrolysis stage during AD and hence pre-treatment is required to overcome the issue. This paper aimed to study the effect of electrochemical pre-treatment (EP) towards efficiency of AD using titanium coated with ruthenium oxide (Ti/RuO2) electrodes. The investigation has been carried out using in-house laboratory batch-scale mesophilic anaerobic digester, mixed under manipulation of important operating parameters. Optimization was performed on EP using response surface methodology and central composite design to maximize sludge disintegration and dewaterability. By operating at optimal conditions (pH 11.65, total solids 22,000 mg/L, electrolysis time 35 min, current density 6 mA/cm2, and 1000 mg/L of sodium chloride), the pre-treated WAS in terms of mixed liquor volatile suspended solids (MLVSS) removal, soluble chemical oxygen demand (sCOD), capillary suction time (CST) reduction, and extracellular polymeric substance (EPS) were 38%, 4800 mg/L (increased from 935 mg/L), 33%, and 218 mg/L, respectively. Following AD, the volatile solids (VS) removal and chemical oxygen demand (COD) removal by EP were enhanced from 40.7% and 54.7% to 47.2% and 61.5%, respectively, at steady-state. The biogas produced from control and electrochemical pre-treated WAS were in the ranges of 0.12 to 0.17 and 0.2 to 0.24 m3/kg VSfed, respectively, and the volume of biogas produced was 44–67% over the control. Based on the results obtained, suitability of EP for WAS prior to AD was confirmed.

scholarly journals PENGARUH PENAMBAHAN ZEOLIT ALAM TERMODIFIKASI SEBAGAI MEDIA IMOBILISASI BAKTERI TERHADAP DEKOMPOSISI MATERIAL ORGANIK SECARA ANAEROB

2017 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
Melly Mellyanawaty ◽  
Chandra Wahyu Purnomo ◽  
Wiratni Budhijanto
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Oxygen Demand ◽  
Total Solid ◽  
Volatile Solid ◽  
Spent Wash ◽  
Distillery Spent Wash ◽  
Soluble Chemical Oxygen Demand

Penelitian ini bertujuan untuk mengetahui pengaruh penambahan zeolit alam termodifikasi sebagai media imobilisasi terhadap dekomposisi material organik pada proses anaerobic digestion. Modifikasi yang dilakukan adalah dengan cara mengimpregnasi ion besi(Fe2+)ke dalam zeolit yang telah dibentuk menjadi cincin Raschig. Impregnasi yang dilakukan adalah impregnasi basah. Dalam penelitian ini digunakan 3 variasi konsentrasi larutan Fe2+ yaitu 10 mg/L; 100 mg/L dan 2000 mg/L. Dari hasil impregnasi zeolit menggunakan ketiga konsentrasi tersebut diperoleh kadar Fe2+ yang terdeposit ke dalam zeolit berturut-turut: 0,0016 mgFe2+/gZeo; 0,0156 mgFe2+/gZeo; 0,3125 mgFe2+/gZeo dan 0 mgFe2+/gZeo digunakan sebagai kontrol. Zeolit termodifikasi Fe2+ kemudian ditambahkan ke dalam reaktor anaerobik yang dijalankan secara batch. Perbandingan volume media zeolit dan cairan adalah 1:1. Substrat yang digunakan berupa campuran limbah distillery spent wash dengan konsentrasi soluble Chemical Oxygen Demand (sCOD) 10.000 mg/L dan keluaran dari digester aktif kotoran sapi sebagai inokulum. Perbandingan volume distillery spent wash terhadap inokulum sebesar 2:1. Proses anaerobik dijalankan selama 28 hari.Jika dibandingkan dengan data Total Solid (TS) dan Volatile Solid (VS), hasil percobaan menunjukkan bahwa data analisis sCOD memberikan data yang lebih akurat dan konklusif untuk mengukur perubahan material organik dalam proses peruraian anaerobik menggunakan media imobilisasi. Dari keempat variasi kadar Fe2+ yang digunakan dalam penelitian ini, Fe2+ dengan kadar 0,0156 mgFe/gZeo memberikan efisiensi penurunan material organik (sCOD) tertinggi yaitu 66,73%. Sedangkan Fe2+ dengan kadar 0,3125 mgFe/gZeo mampu meningkatkan produksi biogas sebesar 43%. Namun secara keseluruhan proses peruraian anaerobik yang menggunakan zeolit termodifikasi Fe2+ menghasilkan biogas lebih banyak daripada kontrol (zeolit tanpa Fe2+).

scholarly journals Improvement of Waste Dehydrated Sludge for Anaerobic Digestion through High-Temperature and High-Pressure Solubilization

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 88 ◽  
Author(s):  
Eui-Hwan Hong ◽  
Jun-Gyu Park ◽  
Beom Lee ◽  
Wei-Qi Shi ◽  
Hang-Bae Jun
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Oxygen Demand ◽  
Stable Operation ◽  
Thermal Hydrolysis ◽  
Methane Generation ◽  
Methane Potential ◽  
Higher Temperature ◽  
Soluble Chemical Oxygen Demand ◽  
Pre Treatment

Biochemical methane potential tests and lab-scale continuous experiments were conducted to improve the yield and energy efficiency of anaerobic digestion through thermal hydrolysis pre-treatment. Methane generation, yield, and solubilization efficiency were evaluated through lab-scale tests. The pre-treated samples presented 50% biodegradability at 140 °C and 61.5% biodegradability at 165 °C. The increase in biodegradability was insignificant at 165 °C or higher temperature, and it was confirmed that the optimum conditions were achieved at 165 °C and 20 min of solubilization. The lab-scale continuous experiments confirmed that polymers were decomposed into low-molecular-weight compounds due to thermal hydrolysis, and pH decreased. NH4HCO3 produced by thermal hydrolysis acted as an alkali to enable a more stable operation compared to that before thermal hydrolysis. Total chemical oxygen demand as chromium (TCODCr) and soluble chemical oxygen demand as chromium (SCODCr) indicated 35.4% and 23.1% removal efficiency in terms of organic matter removal, respectively. Methane yield was approximately 0.35 kg m−3 at 2.0–4.0 kg (m3 d)−1 and 0.26 kg m−3 at 5.0 kg (m3 d)−1. The solubilization rate of 40.9% by thermal hydrolysis was confirmed through the lab-scale tests to determine its full-scale applicability.

The Comparison of Substrate Changes in Microbial Fuel Cells Using Excess Sludge and Simple Anaerobic Digestion

2013 ◽  
Vol 864-867 ◽  
pp. 1839-1842
Author(s):  
Xiao Qin Zhao ◽  
Xiao Jie Sun ◽  
Su Na Wei ◽  
Jiang Cheng Liang ◽  
Yang Yang ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Microbial Fuel Cells ◽  
Oxygen Demand ◽  
Control Device ◽  
Excess Sludge ◽  
Upward Trend ◽  
Air Cathode ◽  
Soluble Chemical Oxygen Demand

Based on the previous studies, this experiment presented a new kind of microbial fuel cells (MFC), single-chamber air cathode microbial fuel cells without proton membrane. After investigating the contrast of substrate changes in microbial fuel cells and simple anaerobic digestion, the analysis results of soluble chemical oxygen demand (SCOD), TP, TN and NH3-N show that: SCOD increase firstly, then decrease, to the end, descend. As a result, we find that SCOD in MFC is lower than that in control device (CD). Throughout the whole reaction period, TP in MFC is lower than that in CD. TN and NH3-N show upward trend after a reaction period.

scholarly journals Enrich waste activated sludge digestibility via natural enzyme supplementation

2019 ◽  
Vol 83 ◽  
pp. 01012 ◽  
Author(s):  
Mohamed Elsamadony
Keyword(s):  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Suspended Solids ◽  
Carica Papaya ◽  
Oxygen Demand ◽  
Total Suspended Solids ◽  
Enzyme Concentration ◽  
Waste Activated Sludge ◽  
Protein Molecules ◽  
Natural Enzyme

Upgrading of low biodegradable waste activated sludge (WAS) accomplished through supplement the hydrolysis step with natural enzymes source. Whereas, WAS is rich in particulate fractions in terms of total chemical oxygen demand (tCOD), total suspended solids (TSS) and volatile suspended solids (VSS) of 15.78, 14.92 and 12.15 g/L, respectively. Therefore, carica papaya enzymes were utilized to break down the peptide ponds in protein molecules such as papain and protease, as well as, lipases that catalyzed the degradation of lipids. The optimum mixture between papain, protease, and lipase enzymes was found to be 3: 1: 2 while the optimum enzyme concentration was 8%. This conditions was attributed to enhance the H2 productivity form WAS by 97.8%

scholarly journals Peningkatan Produksi Biogas dari Palm Oil Mill Effluent (POME) dengan Fluidisasi Media Zeolit Termodifikasi pada Sistem Batch

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Firda Mahira Alfiata Chusna ◽  
Melly Mellyanawaty ◽  
Estin Nofiyanti
Keyword(s):  
Anaerobic Digestion ◽  
Chemical Oxygen Demand ◽  
Trace Element ◽  
Palm Oil ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Organic Content ◽  
Palm Oil Mill Effluent ◽  
Soluble Chemical Oxygen Demand ◽  
Palm Oil Mill

The production of crude palm oil (CPO) in Indonesia tends to increase over time. Palm oil mill effluent (POME) is the wastewater generated from the palm oil mill process with high organic content. POME is a potential source for anaerobic digestion due to its high organic content. The challenge of POME treatment using an anaerobic process is to enhance biogas production with high soluble chemical oxygen demand (sCOD) removal efficiency. The purpose of this study was to evaluate the effect of selected trace elements addition onto zeolite as immobilization media to the anaerobic digestion of POME in a fluidized batch system. Natural zeolite was used as the medium to immobilize microorganisms in an anaerobic fluidized bed reactor (AFBR). This study used three trace elements impregnated to natural zeolites, i.e. Ni2+, Zn2+, Mg2+. The result shows that Ni2+ and Zn2+ improve the methanogenesis process, prevent the accumulation of VFA as an intermediate product and increase the methane (biogas) production. Meanwhile, Mg2+ only reduced sCOD significantly but it did not affect methane production. Fluidization enhanced the performance of the POME anaerobic digestion process. The fluidization provide a positive effect to enhance biogas production and sCOD removal. The efficiency of sCOD removal in the entire reactors were 80.82%; 81.77%; 75.89% for AFBR-Ni; AFBR-Zn and AFBR-control respectively. The total volume of methane produced by the three AFBR were 163,04; 136,42; 62,79 (in ml CH4 / g sCOD) for AFBR-Ni; AFBR-Zn and AFBR-control, respectively. A B S T R A KProduksi crude palm oil (CPO) di Indonesia cenderung meningkat seiring bertambahnya waktu. Palm oil mill effluent (POME) adalah air limbah yang dihasilkan dari proses penggilingan kelapa sawit dengan kandungan organik yang tinggi. Tantangan dalam mengolah POME menggunakan proses peruraian anaerobik adalah untuk meningkatkan produksi biogas dengan efisiensi penurunan soluble chemical oxygen demand (sCOD) yang tinggi. Tujuan dari penelitian ini adalah mengevaluasi pengaruh penambahan trace element terseleksi pada media imobilisasi zeolit terhadap proses peruraian anaerobik limbah POME dengan sistem batch terfluidisasi. Zeolit alam berperan sebagai media imobilisasi mikroorganisme dalam anaerobic fluidized bed reactor (AFBR). Penelitian ini menggunakan tiga trace element yang diimpregnasikan pada zeolit alam yaitu Ni2+, Zn2+, Mg2+. Hasil penelitian menunjukkan bahwa Ni2+ dan Zn2+ sebagai trace element dapat meningkatkan proses metanogenesis dan mencegah akumulasi VFA sebagai produk antara serta meningkatkan produksi gas metana (biogas). Mg2+ sebagai trace element menurunkan sCOD dengan cukup signifikan namun tidak diimbangi dengan banyaknya metana yang dihasilkan. Fluidisasi meningkatkan performa dari proses peruraian anaerobik POME. Proses fluidisasi memberi pengaruh positif dalam meningkatkan produksi biogas dan soluble chemical oxygen demand (sCOD) removal. Nilai sCOD removal yaitu 80,82%; 81,77%; 75,89% berturut-turut untuk AFBR-Ni; AFBR-Zn dan AFBR-kontrol. Total volume metana yang dihasilkan oleh ketiga AFBR yaitu 163,04; 136,42; 62,79 (dalam ml CH4 / g sCOD) berturut-turut untuk AFBR-Ni; AFBR-Zn dan AFBR-kontrol.

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