scholarly journals Product Concentration, Yield and Productivity in Anaerobic Digestion to Produce Short Chain Organic Acids: A Critical Analysis of Literature Data

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1538
Author(s):  
Serena Simonetti ◽  
Agus Saptoro ◽  
Claudia Fernández Martín ◽  
Davide Dionisi
Keyword(s):  
Anaerobic Digestion ◽  
Residence Time ◽  
Oxygen Demand ◽  
Short Chain ◽  
Feed Concentration ◽  
Product Concentration ◽  
Hydraulic Residence Time ◽  
Mean Values ◽  
Performance Variables ◽  
The Mean

In order to make anaerobic digestion-based processes for short chain organic acid (SCOA) production attractive, the key performance variables, i.e., concentration, yield, and productivity of the produced SCOAs need to be maximised. This study analysed recent literature, looking for the effect of process operating parameters (feed concentration, pH, temperature, and residence time) on the performance variables. Data from 551 experiments were analysed. Mean values of the SCOA concentration, yield, and productivity were 10 g l−1, 32% (chemical oxygen demand (COD) COD−1), and 1.9 g l−1 day−1, respectively. Feed concentration and residence time had the most important effect. Higher feed concentration corresponded to higher product concentration and productivity, but to lower yield. The mean feed concentration was 109 gCOD l−1 and 19 gCOD l−1 in the experiments with the highest product concentrations and in the experiments with the highest yields, respectively. Shorter residence times corresponded to higher productivity. The mean HRT (hydraulic residence time) in the experiments with the highest productivities was 2.5 days. Sequencing batch reactors gave higher values of the performance variables (mean values 29 g l−1, 41% COD COD−1, and 12 g l−1 day−1 for product concentration, yield, and productivity, respectively) than processes without phase separation.

scholarly journals Evaluation of Physicochemical Characteristics of Surface Water from Orashi River, Rivers State, Southern Nigeria

2021 ◽  
Vol 8 (2) ◽  
pp. 105-122
Author(s):  
Onisogen Simeon Edori ◽  
Enize Simeon Edori
Keyword(s):  
Suspended Solids ◽  
Oxygen Demand ◽  
Physicochemical Characteristics ◽  
Total Dissolved Solids ◽  
Standard Laboratory ◽  
Mean Values ◽  
Drinking Purposes ◽  
The Mean ◽  
One Year ◽  
Rivers State

Water samples were collected from four different stations bimonthly from the Orashi River for a period of one year. The samples were collected from the shores of selected communities along the Engenni axis of the river. The samples were treated and analyzed according to standard laboratory and analytical procedures for water physicochemical parameters. The parameters examined were pH, Salinity, chlorides (Cl-), Conductivity, total dissolved solids (TDS), total suspended solids (TSS) turbidity, temperature, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrates (NO3-), sulphate (SO42-) and phosphates (PO43-). The results showed that the mean values of the evaluated parameters were; pH (6.91±0.11), salinity (9.79±0.27 mg/L), Cl (6.25±0.25 mg/L), conductivity (29.66±1.20 µS/cm), TDS (17.66±2.08 mg/L), TSS (16.83±1.15 mg/L), turbidity (11.84±1.50 mg/L), temperature (28.16±0.12 oC), DO (5.91±0.18 mg/L), BOD (7.30±0.60 mg/L), COD (9.41±0.70 mg/L), NO3- (3.42±0.27 mg/L), SO42- (1.15±0.56 mg/L) and PO43- (15.65±5.76 mg/L). The results of the different parameters showed that all of them fall within the WHO acceptable limit except turbidity, DO and BOD that were not within the recommended range, then COD and phosphates that were either within or above the recommended values at different instances. Based on the findings of this work, the water may not be particularly suitable for drinking purposes, but can be used for other household functions that do not require consumption and also for irrigation. Keywords: water, physicochemical property, human activity, environment, contamination

Simultaneous autotrophic denitrification and nitrification in a low-oxygen reaction environment

2014 ◽  
Vol 70 (4) ◽  
pp. 729-735 ◽  
Author(s):  
Ganapathy Ramanathan ◽  
Christopher M. Sales ◽  
Wen K. Shieh
Keyword(s):  
Residence Time ◽  
Oxygen Demand ◽  
Autotrophic Denitrification ◽  
Low Oxygen ◽  
Total N ◽  
N Removal ◽  
Bioreactor System ◽  
The Mean ◽  
The Stability ◽  
Ammonia Oxidising Bacteria

The occurrence of autotrophic denitrification and nitrification activities by ammonia-oxidising bacteria and nitrite-oxidising bacteria is studied in a bioreactor system operable at low-dissolved oxygen (DO) and at variable oxygen influx rates. At a loading of 3.6 mg NH4+–N/h into the bioreactor, simultaneous autotrophic denitrification and nitrification contributed to NH4+–N removal over oxygen influxes of 2–14 mg O2/h and DO <0.5 mg/L. The maximum autotrophic denitrification (or total-N removal) rates were achieved in a narrow oxygen influx band of 3–5 mg O2/h, where it accounted for up to 36% of NH4+–N removal. At oxygen influx >16 mg O2/h and DO >2 mg/L, autotrophic denitrification ceases and roughly 90% of feed NH4+–N is oxidised to NOX−–N. The stability of total effluent chemical oxygen demand (COD) over the range of oxygen influxes tested confirms the absence of heterotrophic denitrification in the bioreactor. The long solids residence time of the stable biomass zone (21 days) led to production of effluent COD as a result of cell decay, and thus effluent COD was used to calculate more accurately the mean cell residence time.

scholarly journals Start-up of horizontal anaerobic reactors with sludge blanket and fixed bed for wastewater treatment from coffee processing by wet method

2013 ◽  
Vol 33 (2) ◽  
pp. 353-366 ◽  
Author(s):  
Roberto A. de Oliveira ◽  
Natani M. N. Bruno
Keyword(s):  
Fixed Bed ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Mean Value ◽  
Treatment System ◽  
Anaerobic Sludge ◽  
Mean Values ◽  
Anaerobic Reactors ◽  
Start Up ◽  
The Mean

In this study it was evaluated the start-up procedures of anaerobic treatment system with three horizontal anaerobic reactors (R1, R2 and R3), installed in series, with volume of 1.2 L each. R1 had sludge blanket, and R2 and R3 had half supporter of bamboo and coconut fiber, respectively. As an affluent, it was synthesized wastewater from mechanical pulping of the coffee fruit by wet method, with a mean value of total chemical oxygen demand (CODtotal) of 16,003 mg L-1. The hydraulic retention time (HRT) in each reactor was 30 h. The volumetric organic loading (VOL) applied in R1 varied from 8.9 to 25.0 g of CODtotal (L d)-1. The mean removal efficiencies of CODtotal varied from 43 to 97% in the treatment system (R1+R2+R3), stabilizing above 80% after 30 days of operation. The mean content of methane in the biogas were of 70 to 76%, the mean volumetric production was 1.7 L CH4 (L reactor d)-1 in the system, and the higher conversions were around at 0.20 L CH4 (g CODremoved)-1 in R1 and R2. The mean values of pH in the effluents ranged from 6.8 to 8.3 and the mean values of total volatile acids remained below 200 mg L-1 in the effluent of R3. The concentrations of total phenols of the affluent ranged from 45 to 278 mg L-1, and the mean removal efficiency was of 52%. The start-up of the anaerobic treatment system occurred after 30 days of operation as a result of inoculation with anaerobic sludge with active microbiota.

Modeling the influence of salmon spawning on hyporheic exchange of marine-derived nutrients in gravel stream beds

2015 ◽  
Vol 72 (8) ◽  
pp. 1146-1158 ◽  
Author(s):  
Todd H. Buxton ◽  
John M. Buffington ◽  
Daniele Tonina ◽  
Alexander K. Fremier ◽  
Elowyn M. Yager
Keyword(s):  
Residence Time ◽  
Hyporheic Zone ◽  
Hyporheic Exchange ◽  
Volume Flux ◽  
Hydraulic Residence Time ◽  
Bed Porosity ◽  
Stream Beds ◽  
The Mean ◽  
Stream Bed ◽  
Marine Derived Nutrients

Salmon that spawn in streams deliver marine-derived nutrients (MDN) that catalyze trophic productivity and support rearing juvenile salmon. Salmon spawning also affects hyporheic exchange and movement of dissolved MDN through the stream bed by creating redd topography that induces pumping exchange and by winnowing fine sediment and loosening the bed, which alters hydraulic conductivity and bed porosity. The spatial extent of spawning within the channel likely governs the volume and rate of dissolved MDN exchanged with the stream bed through this process. To explore this issue, we used a two-dimensional groundwater model to predict changes in hyporheic volume, flux, and mean hydraulic residence time of dissolved MDN as a function of the proportion of the bed surface occupied by redds (P). Predictions indicate that hyporheic volume and flux systematically increase with P, while the mean hydraulic residence time of dissolved MDN in the hyporheic zone decreases sharply with P, from 5.79 h on an unspawned bed (P = 0) to 0.03 h for a mass-spawned bed (P = 1.0). Shorter residence time results from hyporheic flux increasing faster than hyporheic volume with higher P. Implications for uptake of dissolved MDN are explored with Damköhler numbers, defined as the ratio of the mean hydraulic residence time to a biogeochemical rate of interest. Given the considerable influence of spawning on hyporheic exchange, additional research is needed to determine conditions under which bioassimilation of dissolved MDN is limited by nutrient supply, extent of the hyporheic zone, or processing rate of MDN in stream beds.

scholarly journals Characteristics of artisanal fisheries in the upper reaches of Bonny Estuary, Niger Delta, Nigeria

2019 ◽  
Vol 4 (6) ◽  
Author(s):  
Daniel Utibe I ◽  
Monsi BG
Keyword(s):  
Oxygen Demand ◽  
Fish Growth ◽  
Artisanal Fisheries ◽  
Chemical Parameters ◽  
Wet Season ◽  
Mean Values ◽  
Access To Credit ◽  
Physico Chemical ◽  
The Mean ◽  
Laws And Policies

Characteristics of artisanal fisheries in the upper reaches of Bonny Estuary were investigated for a period of six months from December 2014 to June 2015. Data were collected from randomly selected fishermen from five communities, viz., Bodo, Kpor, Bomu, Lewe and Gbe, using interview and open ended structured questionnaire. The research was carried out to ascertain the fish existed in the study area, types of gear, and methods of fishing, preservation and marketing techniques. The mean values of physico-chemical parameters such as temperature, dissolved oxygen (D.O), salinity, pH, turbidity, and biological oxygen demand (BOD) were 30.47±1.34˚C, 8.64±1.24 mg/l, 16.4±5.78 ppt, 7.66±0.76, 117.0±16.9 NTU and 4.94±2.66 mg/l, respectively. A total of 52 fish species belonging to 24 families were identified and the species diversity and their abundance were determined. Tilapia guineensis was the highest in number (190) with 4.0% of abundance, while Sphryraena afra was the least in number (9) with 2.0% of abundance. The dry season (December–February) recorded the number of 2,772 (57.7%) fin fishes, while the wet season (April–June) found 2,028 (42.3%). The mean number of fish caught was highest in station 2 and lowest in station 4. The physico chemical parameters were within the acceptable limits for fish growth in brackish water ecosystem. The study revealed that the gear commonly used by the fishermen include cast nets, drag nets, hook and line, and traps, while the crafts used were mainly dug-out canoe and non-motorised boat. It also revealed that the constraints responsible for the low catch and poor standard of living of the fishermen as observed include high cost of gear materials, poor condition of boat, no access to credit facilities, destruction of nets by engine boat and environmental pollution. In view of the negative impacts that the aforementioned factors have on the fishermen, it is necessary to implement an effective management of the fisheries through proper enforcement and environmental laws and policies to safeguard and conserve the aquatic biota from going into extinction as well as restoring the source of livelihood to the fishermen in the area under investigation.

scholarly journals Comparative Physicochemical and Microbiological Qualities of Source and Stored Household Waters in Some Selected Communities in Southwestern Nigeria

2017 ◽  
Author(s):  
Mary A. Bisi-Johnson ◽  
Kehinde A. Adediran ◽  
Saheed A. Akinola ◽  
Elizabeth O. Popoola ◽  
Anthony I. Okoh
Keyword(s):  
Water Samples ◽  
Oxygen Demand ◽  
Enterobacter Aerogenes ◽  
Total Hardness ◽  
Klebsiella Pneumonia ◽  
Indicator Organisms ◽  
Candida Spp ◽  
Southwestern Nigeria ◽  
Mean Values ◽  
The Mean

In this study, we evaluated the physicochemical and microbial qualities of source and stored household waters in some communities in Southwestern Nigeria using standard methods. Compared parameters include physicochemical constituents; Temperature (T), pH, Total Dissolved Solids (TDS), Total Hardness (TH), Biological Oxygen Demand (BOD), Magnesium ion (Mg2+) and Calcium ion (Ca2+) and microbiological parameters included Total Coliform Counts (TC), Faecal Coliform Counts (FC), Fungal Counts (Fung C), Heterotrophic Plate Counts (HPC). Comparing Stored and Source samples, the mean values of some physicochemical parameters of most of the stored water samples significantly (P<0.05) exceeded that of Sources and ranged in the following order: T (15.3±0.3oC - 28.3±0.5oC), pH (6.4±0.1 - 7.6±0.1), TDS (192.1±11.1 ppm - 473.7±27.9 ppm), TH (10.6±1.7 mg/L - 248.6±18.6 mg/L), BOD (0.5±0.0 mg/L - 3.2±0.3 mg/L), Mg2+ (6.5±2.4 mg/L - 29.1±3.2 mg/L) and Ca2+ (6.5±2.4 mg/L - 51.6±4.4 mg/L). The mean microbial counts obtained from microbial comparison of different points (Stored and Source) of collection showed that most of the stored water had counts significantly exceeding (P<0.05) those of the source water samples (cfu/100 mL) which ranged as follows: TC (3.1±1.5 - 156.8±42.9), FC (0.0±0.0 - 64.3±14.2) and HPC (47.8±12.1 - 266.1±12.2) across all sampled communities. Also, the predominant isolates recovered from the samples were identified as Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Enterobacter aerogenes, Aspergillus spp, Mucor spp, Rhizopus spp and Candida spp. The presence of these pathogenic and potentially pathogenic organisms in the waters and the high counts of the indicator organisms suggest the waters to be a threat to public health.

scholarly journals Assessment of three different parameters of urban ponds at Rajshahi, Bangladesh

2012 ◽  
Vol 19 ◽  
pp. 59-63
Author(s):  
FA Flowra ◽  
JK Ghosh ◽  
AS Tumpa ◽  
SN Jahan
Keyword(s):  
Water Quality ◽  
Water Temperature ◽  
Oxygen Demand ◽  
Mean Value ◽  
Ammonium Ion ◽  
Total Hardness ◽  
Mean Values ◽  
Physico Chemical ◽  
The Mean ◽  
Carbon Dioxide Co2

Context: Physico-chemical factors directly affect the water quality. Biological parameters varied from pond to pond according to the water quality. Objective: To assess the physico-chemical conditions and plankton abundance in the studied ponds. Materials and Methods: The study was carried out for a period of seven months from June, 2008 to December, 2008 in six ponds of Rajshahi Metropolitan area. Surface water samples were collected once a month at 10-11 am in black plastic bottle and analyzed for the estimation of different parameters. Water temperature, transparency, pH, dissolved oxygen (DO), free carbon dioxide (CO2), biological oxygen demand (BOD), nitrite nitrogen (NO2––N), nitrite (NO2), toxic ammonia, ammonium ion (NH4+) and total hardness were measured. The density of plankton was also estimated. Results: The mean values of water temperature varied from 28.73 ± 3.98 (Pond 6) to 29.56 ± 4.68°C (Pond 4) and the pH varied from 7.37 ± 0.26 (Pond 6) to 8.57±0.26 (Pond 4). The DO varied 1.66 ± 1.03 (Pond 1) to 4.68 ± 0.36 mg/l (Pond 6) and the mean value of free CO2 varied from 4.29 ± 0.37 (Pond 5) to 50.91 ±19.30 mg/l (Pond 3). The total hardness was 136.79 ± 20.28 (Pond 6) to 183.14 ± 51.17 mg/l (Pond 3) with NO2–varied from 0.003 ± 0.002 (Pond 5) to 2.08 ± 0.59 mg/l (Pond 4). The mean total phytoplankton was 28761.43 ± 2912.62 (Pond 2) to 63629.29 ± 20214.44 cells/l (Pond 4) and the mean total zooplankton was 13314.24 ± 3189.70 cells/l (Pond 5) to 18820.00 ± 932.51 cells/l (Pond 4). Conclusion: The deterioration in the physico-chemical quality and plankton population observed in this study is alarming, and periodic monitoring and preventative measures are required to save the aquatic system from eutrophication. DOI: http://dx.doi.org/10.3329/jbs.v19i0.13002 J. bio-sci. 19 59-63, 2011

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

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