Chemical Oxygen Demand Analysis of Anaerobic Digester Contents

An anaerobic digester converts organic materials into biogas and digestate in the absence of oxygen. The organic materials studied in this experiment include fibres (types of paper or cardboard), food waste, and woodchips, which serve as a bulking agent. To analyze digester performance, it is necessary to calculate an accurate mass balance based on the chemical oxygen demand (COD) entering and exiting the system. Digester performance refers to maximum efficiency and biogas yield. The COD of the biogas is known, but that of the feed and the digestate is not. This paper describes a method for measuring the COD of the feed materials and the digestate by creating representative aqueous suspensions of each. The challenges are to ensure that the suspensions are representative of the feed or digestate, and that samples of the suspension extracted for COD analysis are consistent and reproducible. To obtain an accurate COD measurement of the feed and digestate samples, a specific procedure was developed: each material was processed in a blender with deionized water, creating a pulp from which samples were pipetted during continuous mixing of the suspension. The conducted trials provided COD content values ranging from 1.27-1.59 g of COD/ g of dry feed, depending on the fibre. Standard deviations of the COD content ranged from 2.8% to 12.7%, indicating that the procedure is reliable and the results precise. The measured COD content values allow an accurate mass balance of the digester to be determined, ultimately providing a better understanding of the system as the total digestible material entering the digester will be known. An accurate mass balance can improve the efficiency of the digester in order to produce optimal quantities of biogas. The biogas can be harnessed into energy from otherwise useless waste. Further study in this topic can explore the COD content of wider ranges of organic solids as well as further optimize the procedure in order to provide even more accurate results.

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Removal of Reactive Green 12 Dye and COD from Simulated Wastewater Using Different Coagulants

Association of Arab Universities Journal of Engineering Sciences ◽

10.33261/jaaru.2019.26.2.002 ◽

2019 ◽

Vol 26 (2) ◽

pp. 6-11

Author(s):

Tamara Kawther Hussein ◽

Nidaa Adil Jasim

Keyword(s):

Chemical Oxygen Demand ◽

Ferric Chloride ◽

Ferrous Sulphate ◽

Oxygen Demand ◽

Maximum Efficiency ◽

Maximum Volume ◽

Jar Test ◽

Aluminum Sulphate ◽

Simulated Wastewater

The ability of using each of the following: aluminum sulphate (Al2(SO4)3.16H2O), ferric chloride (FeCl3), and ferrous sulphate (FeSO4) as chemical coagulants was investigated for removing of reactive green 12 (RG 12) dye and chemical oxygen demand (COD) from simulated wastewater. Best pH , coagulants dosages, and initial concentrations were obtained by jar test. The maximum efficiency for removing RG-12 and COD recorded by ferric chloride were 98% and 88 %, by alum were 95% and 88%, and by ferrous sulphate were 70% and 50%. All these results obtained at the best pH 6, dosage 100 mg/l and initial concentrations for RG-12 and COD 50 mg/l and 600 mg/l respectively. The maximum volume of sludge was for alum coagulant 14 ml/l, 12 ml/l for ferric chloride and 0.5 ml/l for ferrous sulphate. The study improved that it is possible to use each of aluminum sulphate, ferric chloride and ferrous sulphate as an economical coagulant to treat the wastewater which it is polluted with RG 12 dye and COD.

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Coupled anaerobic–aerobic treatment of whey wastewater in a sequencing batch reactor: proof of concept

Water Science & Technology ◽

10.2166/wst.2007.323 ◽

2007 ◽

Vol 55 (10) ◽

pp. 201-208 ◽

Cited By ~ 2

Author(s):

J.C. Frigon ◽

T. Bruneau ◽

R. Moletta ◽

S.R. Guiot

Keyword(s):

Chemical Oxygen Demand ◽

Sequencing Batch Reactor ◽

Batch Reactor ◽

Oxygen Demand ◽

Anaerobic Digester ◽

Aerobic Treatment ◽

Proof Of Concept ◽

Ph Shock ◽

Soluble Chemical Oxygen Demand ◽

Different Levels

A proof of concept was performed in order to verify if the coupling of anaerobic and aerobic conditions inside the same digester could efficiently treat a reconstituted whey wastewater at 21 °C. The sequencing batch reactor (SBR) cycles combined initial anaerobic phase and final aerobic phase with reduced aeration. A series of 24 h cycles in 0.5 L digesters, with four different levels of oxygenation (none, 54, 108 and 182 mgO2 per gram of chemical oxygen demand (COD)), showed residual soluble chemical oxygen demand (sCOD) of 683±46, 720±33, 581±45, 1,239±15 mg L−1, respectively. Acetate and hydrogen specific activities were maintained for the anaerobic digester, but decreased by 10–25% for the acetate and by 20–50% for the hydrogen, in the coupled digesters. The experiment was repeated using 48 h cycles with limited aeration during 6 or 16 hours at 54 and 108 mgO2gCOD−1initial, displaying residual sCOD of 177±43, 137±38, 104±22 and 112±9 mg L−1 for the anaerobic and the coupled digesters, respectively. The coupled digesters recovered after a pH shock with residual sCOD as low as 132 mg L−1 compared to 636 mg L−1 for the anaerobic digester. With regard to the obtained results, the feasibility of the anaerobic- aerobic coupling in SBR digesters for the treatment of whey wastewater was demonstrated.

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Effect of rapid batch decompression on hydrolysate quality after hydrothermal pretreatment of wheat straw

Chemical Papers ◽

10.1515/chempap-2015-0188 ◽

2015 ◽

Vol 69 (12) ◽

Author(s):

Lukáš Krátký ◽

Tomáš Jirout

Keyword(s):

Chemical Oxygen Demand ◽

Wheat Straw ◽

Residence Time ◽

Oxygen Demand ◽

Hydrothermal Pretreatment ◽

Process Temperature ◽

Glucose Content ◽

Biogas Yield ◽

Rapid Decompression ◽

The Subject

AbstractThe subject of this paper was to study the effect of rapid batch decompression on hydrolysate quality and on biogas yield after the hydrothermal pretreatment of wheat straw. An aqueous batch containing 5 mass % total solids of wheat straw was thermally and thermally-expansionary treated in parallel at the process temperature of 170-200°C and the residence time of 0-60 min. An analysis of the thermal and thermal-expansionary hydrolysate provided identical results in the dependences and values of chemical oxygen demand, acidities, and glucose yields of both treatments based on severity factors including the combined effects of temperature and residence time. Increases in the methane content of 33 % for thermally and of 34 % for thermally-expansionary treated wheat straw were reached in comparison to the methane yield from an untreated sample. This means that the polysaccharide cell wall was dissolved because of the high process temperature and residence time. From this it follows that all its nutrients were subsequently washed out of the cell into liquid where they caused changes in its chemical oxygen demand, glucose content, and acidities. There was therefore no rapid decompression effect on the hydrothermally treated wheat straw.

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Integral Application of Chemical Mass Balance and Watershed Model to Estimate Point and Nonpoint Source Pollutant Loads in Data-Scarce Little Akaki River, Ethiopia

Sustainability ◽

10.3390/su12177084 ◽

2020 ◽

Vol 12 (17) ◽

pp. 7084

Author(s):

Zelalem Abera Angello ◽

Beshah M. Behailu ◽

Jens Tränckner

Keyword(s):

Chemical Oxygen Demand ◽

Mass Balance ◽

Biochemical Oxygen Demand ◽

Oxygen Demand ◽

Nonpoint Source ◽

Chemical Mass Balance ◽

Pollution Load ◽

Watershed Model ◽

Total Dissolved Solid ◽

Akaki River

The quality of Little Akaki River in Addis Ababa (Ethiopia) is deteriorating significantly due to uncontrolled waste released from point and diffuse sources. In this study, pollution load from these sources was quantified by integrating chemical mass balance analysis (CMB) and the watershed model of pollution load (PLOAD) for chemical oxygen demand, biochemical oxygen demand, total dissolved solid, total nitrogen, nitrate, and phosphate. Water samples monitored bimonthly at 15 main channel monitoring stations and 11-point sources were used for estimation of pollutant load using FLUX32 software in which the flow from the soil and water assessment tool (SWAT) model calibration, measured instantaneous flow, and constituent concentration were used as input. The SWAT simulated the flow quite well with a coefficient of determination (R2) of 0.78 and 0.82 and Nash-Sutcliff (NSE) of 0.76 and 0.80 during calibration and validation, respectively. The uncharacterized nonpoint source load calculated by integrating CMB and PLOAD showed that the contribution of nonpoint source prevails at the middle and downstream segments of the river. Maximum chemical oxygen demand (COD) load from uncharacterized nonpoint sources was calculated at the monitoring station located below the confluence of two rivers (near German Square). On the other hand, high organic pollution load, biochemical oxygen demand (BOD) load, was calculated at a station upstream of Aba Samuel Lake, whereas annual maximum total dissolved solid (TDS), total nitrogen (TN), and phosphate load (PO4-P) from the nonpoint source in Little Akaki River (LAR) were found at a river section near Kality Bridge and maximum NOX load was calculated at station near German Square. The integration of the CMB and PLOAD model in this study revealed that the use of area-specific pollutant export coefficients would give relatively accurate results than the use of mean and median ECf values of each land use.

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Effect Of Alkaline Pre-Treatment On Cassava Pulp For Optimum Biogas Production

International Journal of Recent Technology and Engineering - 2 ◽

10.35940/ijrte.b3538078219 ◽

2019 ◽

Vol 8 (2) ◽

pp. 5919-5923

Keyword(s):

Chemical Oxygen Demand ◽

Volatile Fatty Acids ◽

Biogas Production ◽

Oxygen Demand ◽

Treatment Method ◽

Batch Mode ◽

Biogas Yield ◽

Cassava Pulp ◽

Soluble Chemical Oxygen Demand ◽

Pre Treatment

(Being produced in vast quantity as one of by-product from cassava starch processing chains, cassava pulp has great potential for energy recovery by harnessing biogas through anaerobic digestion (AD). This study aims to enhance biogas production by comparative investigation in batch mode digestion. 5%TS w/v of cassava pulp mixed with mill effluent were pre-treated with 10 molar potassium hydroxide (KOH), sodium hydroxide (NaOH), and calcium hydroxide (Ca(OH)2) solution for 6 hours contact time. Effects of different alkaline pre-treatment on cassava substrate were assessed in total dissolved solid (TDS), soluble chemical oxygen demand (SCOD), Volatile Fatty Acids to Alkalinity ratio (VFA/TA), and reducing sugars. Daily accumulated biogas yield was taken as final indicator of the effect of different pre-treatment. KOH pre-treatment in pH 11 resulted highest dissolved solid 13.07 mg/L, and improved soluble chemical oxygen demand (SCOD) formation up to 75.61% (480,000 mg/L) than control substrate. The experiment revealed peak biogas production by KOH pre-treated substrate was found at day 6 after digestion executed, and achieved 546 ml. The finding proves out of different pre-treatment method applicable to cassava pulp, KOH pre-treatment could realistically increase biogas yield for cassava mills. Biogas production increased up to 101%, 92%, and 70% using KOH, Ca(OH)2 and NaOH respectively. However, when future provision to the technology for AD system and design is concerned, the choice of highly reactive alkali could lead to complication in the system.

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Chemically Enhanced Primary Sludge as an Anaerobic Co-Digestion Additive for Biogas Production from Food Waste

Processes ◽

10.3390/pr7100709 ◽

2019 ◽

Vol 7 (10) ◽

pp. 709 ◽

Cited By ~ 2

Author(s):

Xiaorong Kang ◽

Yali Liu

Keyword(s):

Chemical Oxygen Demand ◽

Food Waste ◽

Volatile Fatty Acids ◽

Biogas Production ◽

Oxygen Demand ◽

Mechanism Analysis ◽

Primary Sludge ◽

Biogas Yield ◽

Batch Tests ◽

Solids Removal

In order to overcome process instability and buffer deficiency in the anaerobic digestion of mono food waste (FW), chemically enhanced primary sludge (CEPS) was selected as a co-substrate for FW treatment. In this study, batch tests were conducted to study the effects of CEPS/FW ratios on anaerobic co-digestion (coAD) performances. Both soluble chemical oxygen demand (SCOD) and protease activity were decreased, with the CEPS/FW mass ratio increasing from 0:5 to 5:0. However, it was also found that the accumulation of volatile fatty acids (VFAs) was eliminated by increasing the CEPS/FW ratio, and that corresponding VFAs concentrations decreased from 13,872.97 to 1789.98 mg chemical oxygen demand per L (mg COD/L). In addition, the maximum value of cumulative biogas yield (446.39 mL per g volatile solids removal (mL/g VSsremoval)) was observed at a CEPS/FW ratio of 4:1, and that the tendency of coenzyme F420 activity was similar to biogas production. The mechanism analysis indicated that Fe-based CEPS relived the VFAs accumulation caused by FW, and Fe(III) induced by Fe-based CEPS enhanced the activity of F420. Therefore, the addition of Fe-based CEPS provided an alternative method for FW treatment.

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Quantification of organic and nitrogen removal in downflow hanging sponge (DHS) systems as a post-treatment of UASB effluent

Water Science & Technology ◽

10.2166/wst.2010.403 ◽

2010 ◽

Vol 62 (9) ◽

pp. 2121-2127 ◽

Cited By ~ 2

Author(s):

B. Wichitsathian ◽

P. Racho

Keyword(s):

Experimental Data ◽

Chemical Oxygen Demand ◽

Mass Balance ◽

Nitrogen Removal ◽

Oxygen Demand ◽

Organic Substrate ◽

Post Treatment ◽

Tapioca Starch ◽

Starch Wastewater ◽

Process Behavior

The aim of this research was to investigate the nature and composition of organic substrate in two down-flow hanging sponge (DHS) systems using mixed fungal (FDHS) and bacterial (BDHS) cultures treatment for UASB effluent of tapioca starch wastewater, evaluated by COD fractionations and two material balances. The random type DHS reactors were operated as modular columns consisting of four identical segments connected vertically. Results of the wastewater characterization showed that carbonaceous fractions were varied on a function of DHS height. Two balances applied to experimental data were for chemical oxygen demand (COD) and nitrogen (N). Results of mass balance calculations can also be used to examine the process behavior of two DHS systems to improve the organic and nitrogen removal mechanisms.

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DETERMINAÇÃO DO NÚMERO DE CICLOS DE REUSO DO ADSORVENTE CINZA DE CASCA DE ARROZ NO TRATAMENTO DE UM BANHO RESIDUAL DE TINGIMENTO TÊXTIL

Eclética Química Journal ◽

10.26850/1678-4618eqj.v38.1.2013.p176-186 ◽

2017 ◽

Vol 38 (1) ◽

pp. 176

Author(s):

Ivonete O. Barcellos ◽

Thyego De Lima ◽

Ana Maria Blosfeld

Keyword(s):

Chemical Oxygen Demand ◽

Rice Husk ◽

Continuous Flow ◽

Rice Husk Ash ◽

Flow System ◽

Oxygen Demand ◽

Maximum Efficiency ◽

Continuous Flow System ◽

Raw Wastewater

This study evaluated a continuous flow system using rice husk ash as an adsorbent to treat textile bath dyeing residual. The system consisted in recirculating the effluent in a burette containing the adsorbent. This procedure was performed in five cycles of reuse of the adsorbent. Chemical Oxygen Demand and color were determined by the estimate of the adsorbent’s efficiency as a function of time by comparing the cycles of reuse bath dying residual, raw wastewater and wastewater treated with ashes. The maximum efficiency obtained was 91% in the 1st cycle. However, in the 5th cycle the efficiency adsorbent was near 46%.

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