COD Loading Research Articles

Effects of salinity on the respirometric activities of mixed culture bacteria from activated sludge process

Salinity or saltiness is dissolved in water by the relative proportion of salt in a solution. All organisms have to keep their cells alive a water balance in their bodies. The activated sludge process (ASP) containing aerobic microorganisms located nearby the coastal area may be faced the problems of salinity from sea water. In this research, the effects of salinity on the respirometric activities of mixed culture bacteria from activated sludge process were evaluated at different levels of NaCl concentrations ranging between 0-25 g/L in the OxiTop system at the temperature of 20 °C. The oxygen uptake rate (OUR) was used to reveal the effects of salinity. The experiments results indicated that the OURs decreased as the NaCl concentrations increased, resulting in the failures of bacterial osmotic pressure systems and causing the lysis of bacteria. The COD and nitrification were failed because the nitrogen and COD loadings to the systems were increased by the lysis of bacteria.

Treatment of wastewater from coffee (coffea arebica) industries using mixed culture Pseudomonas florescence and Escherichia coli bacteria

Effluents from wet processing of coffee industries pollute water bodies since the wastewater is released to the water bodies' vicinity. The wastes water from these industries affects the surface and groundwater. The study was initiated to treat wastewater effluent coming from the coffee industry in the specific area by using an anaerobic mixed culture ofPseudomonas fluorescence andEscherichia coli bacteria. The treatment reduced BOD5, COD, and TS from its initial concentration of 320.26 mg/l, 1261 mg/l, and 3545 mg/l to 58.37 mg/l, 152 mg/l, and 1198 mg/l, respectively. The study's treatment had reduced the BOD5 load up to 81.67%, the COD load up to 87.94%, and TS load up to 33.79% from the initial load using optimization of the treatment method. Therefore, it can be concluded that mixed culture bacteria ofP. fluorescence andE. colias a new effective treatment having the potential for BOD5, COD, and TS reduction from the effluent. The mixed culture of microorganisms can reduce the contaminants that made the approach cost-effective, time-saving compared with other results found by other studies without mixed culture. The microorganisms included in the study can be applied for the treatment of effluent containing multiple contaminants.

Assessment of water quality of textile effluent and its treatment by using coagulants and plant material

Abstract The present study was conducted to assess the pollution load of textile effluent collected from Jaipur regions and its treatment by plant material. To assess the organic load, BOD and COD were determined and recorded as high values 70 and 2900 mg L-1 respectively. Plant material bark of banana was used to remove pollutants from textile effluent in the combination of coagulants (FeSO4 with CaO). Appreciable reduction in the pollution load of BOD, COD, and improvement in other water quality parameters was observed after the treatment. An integrated approach with chemical and biological materials may be the helpful ineffective treatment of textile effluent to mitigate the detrimental impacts for environmental conservation and health safety.

Calculation of water environmental capacity of Puzhehei Lake

The calculation of water environmental capacity of Puzhehei lake is of great significance for preventing water pollution and protecting water ecological environment of Puzhehei Lake Basin. Based on the lack of hydrological and water quality data in Puzhehei Lake Basin, a large number of basic data were collected through pollution source investigation and water quality monitoring. On this basis, a twodimensional hydrodynamic water quality model of Puzhehei lake was established by using Mike21 model to simulate the migration and diffusion of pollutants into the lake. The current situation of pollution load in Puzhehei lake was analyzed, and the characteristics of water flow, hydrodynamic force and the migration and diffusion law of pollutants in Puzhehei Lake were analyzed. The results show that: ①the annual loads of COD, TN, TP and NH3-N in puzhehai Lake in 2018 are 4090.0t, 401.3t, 34.4t and 122.6t; ②Puzhehei lake is mainly non-point source pollution, and the difference of water environmental capacity between non rainy season and rainy season is very significant.

Potencial bioquímico de metano de águas residuárias da ultrafiltração no processamento da acerola (Malpighia emarginata) verde

Ultrafiltration clarifies fruit juices, in the food industry, but generates retentive, recalcitrant wastewater, which, by its organic nature, may present a potential for biodegradation and methane production. This study aimed to evaluate the biochemical methane potential (BMP) in wastewater from the processing of unripe green acerola, obtaining the mass balance and the speed of organic load removal in COD terms. The BMP assays followed the German Guidelines VDI 4630, by applying three COD loads per liter of reactor vial (0,86 g CDOAplied L-1R, 1,5 g CDOAplied L-1R e 2,0 g CDOAplied L-1R), , in batches, inoculated with the anaerobic sludge from reactors treating domestic sewage, at 30 0C. The pH, COD, and methane production were evaluated every 48 hours. The biodegradability and the decay rate constant of the COD (Kd) were determined, thus obtaining the methanized COD, the COD for the formation of new cells, and the COD present in the wastewater, in the form of volatile acids. The best BMP was 0.100 L CH4 g -1 CDORemoved, the percentages of methanization were above 62 %, and the highest Kd occurred for the lowest load applied. The anaerobic digestion of the wastewater proved viable for in full-scale, with its application being suggested at a pilot scale.

Enhancing algal biomass production and nutrients removal from municipal wastewater via a novel mini photocavity bioreactor

This study presents the use of a novel photocavity reactor in order to intensify the growth rate, biomass and lipid productivity in microalgae. The reactor offers an aseptic approach for better control on growth rate in microalgae.The Absorption Factor (AF), Attenuation Factor (AtF), Modified Fluence Rate (MFR) and water factor of the photo reactor were recorded to be 1.581, 0.267, 0.347 mW/cm2 and 2.072 respectively. The maximum growth rate recorded was 310 mg L−1 inphotocavity reactor. The results clearly indicate that using the stainless steel visible photoreactor can lead to a significant increase in the growth rate (43.3%), productivity of biomass (27-33%) and lipid content (6-8%) in comparison to microalgae cultivated in glass conical flasks (control). COD, total nitrogen, phosphate and bacterial load (colony-forming unit- CFU) were determined in this study. A decrease in COD (180 to 19 mg/l) and CFU (57×109 to 5×101) of wastewater was also recorded in this study.

Formate production from CO2 electroreduction in a salinity-gradient energy intensified microbial electrochemical system

The electricity production of microbial electrochemical system can be substantially strengthened by coupling with a reverse electrodialysis stack which extracts energy from salinity gradient, therefore provides a possible way for value-added products in cathode without external energy input. Here, a microbial reverse-electrodialysis CO2 reduction cell (MRECC) was developed and successfully utilized to drive CO2-to-formate conversion on a Bi/Cu cathode. Results confirmed the optimal anodic COD load and cathodic CO2 flow rate to be 1 g NaAc L−1 and 10 mL min−1. MRECC could yielded 143.5 ± 8.1 mg L−1 of formate with total energy efficiency of 4.6 ± 0.9% and coulombic efficiency of 46.4 ± 2.4%. Increasing or decreasing anode or cathode load impaired MRECC performance from economic and environmental viabilities. MRECC provided a promising platform for simultaneous CO2 reduction and value-added chemicals production by using sustainable energy from wastewaters.

Chlorine dioxide bleaching of nineteen non-wood plant pulps

AbstractBleaching of unbleached and oxygen delignified pulps from nineteen non-wood plants has been evaluated in elemental chlorine free bleaching. Chlorine dioxide charge (kappa factor 0.15, 0.20 and 0.25) and temperature (70 and 85 °C) in the delignification stage (D) were varied. Chlorine dioxide (ClO2) charge and temperature exhibited lower kappa number and higher brightness after alkaline extraction (EP) stage. High temperature ClO2delignification (DHT) exhibited higher final pulp brightness. The final brightness of wheat straw pulp reached to 90 % after D0/DHT(EP)D1bleaching, while banana pseudo stem pulp showed the worst bleachability. Residual hexeneuronic acid contents in final pulp from most of the non-wood plants were lower and exhibited 1–2 % higher pulp brightness in DHTprocess than D0process. Oxygen delignified pulp and DHTprocess discharged lower COD load.

Resistance of Loading Loads in Surabaya River and Its Branch with Qual2KW Model.

Pollution of Surabaya River from year to year is increasing, the increase in pollution is the main problem of Surabaya River which is caused by the entry of most of the liquid waste from industrial, agricultural, and domestic activities. Continuous pollution can reduce water quality for rivers and creeks. One solution that can be applied to reduce the level of pollution is by calculating the capacity of pollution loads. This research was conducted to find out the quality of Kali Surabaya and tributaries of Surabaya River and the calculation of pollution load capacity with the QUAL2KW model. The study analysed the parameters of DO, BOD, COD, and phosphate. From the results of the study, the water quality values for Surabaya river and its branch were above the Class I quality standard Government Regulation Number 82 of 2010 and from the calculation results obtained the maximum capacity values BOD load were 23-1355 kg/day, and COD load were 23-6830 kg/days, while phosphate load were 2,5-125 kg/day.

Vinasse Treatment With Aerobic Microbial Method Using Activated Sludge

Vinasse liquid waste in this study obtained from the ethanol industry which has organic load of COD of 202,232.14 mg/L and BOD of 32,911.47 mg/L. Aeration is used to operate the activated sludge process unit to remove BOD from wastewater in the aerobic microbial method. The research was conducted by conditioning 3L of vinasse wastewater at pH 7 by adding 1 N NaOH, then the acclimatization process was carried out for 24 h using activated sludge with concentration of microorganisms is 13.578 gr/L and 5 L/min of air flow rate in the aeration tank. The processing of vinasse wastewater 3L at pH 7 was carried out on the addition of acclimatized activated sludge microorganisms with quantity 13,578 through 40,734 mg and aeration times in the range of to 2 through 10 h. Removal of organic matter from vinasse waste by activated sludge can be associated with the growth of microorganisms. The results showed that the addition of 40,734 mg of microorganisms for 8 h of aeration obtained the COD removal of 69.273 %, and BOD of 96.652 %.

Selection of optimum biological treatment for coking wastewater using analytic hierarchy process

The design of biological treatment process for the coking wastewater (CW) is complicated since wastewater treatment demand is gradually increasing lacking the systematic strategy in efficiency evaluation and advisable selection. Therefore, this study develops a holistic approach by means of the analytic hierarchy process (AHP) that uses numerical representation to rank the preferences of each participating alternatives for evaluation of the advanced biological technologies in CW treatment. Based on survey results, six types reactor combinations were selected as the alternatives, which were further classified as two group according to COD load. The AHP methodology consists of weighting and ranking procedures considering technical, economic, environmental and administration factors defined as criteria layers. Eighteen indicators were chosen as sub-criteria layers. Inclusively beneficial and sustainable biological processes were assessed and ranked along the AHP implementation. The results placed technical indicators to the top position among the criteria layers in the weighting descending order ‘technical indicators > economic indicators > environmental indicators > administrative indicators’, whereas the weight of indicators in sub-criteria layers fitted in the range of 0.005 to 0.151. The inclusive priority calculation integrating all weight indices of criteria and sub-criteria layers resulted in the anaerobic-anoxic-oxic (A/A/O) combination rising in the hierarchy of the low load group, whereas the oxic-hydrolytic-oxic (O/H/O) process was prioritized in the high load group. The accuracy and objectivity of AHP application was also supported by sensitivity and variability analyses that examines a range for the weights' values and corresponding to alternative scenarios.

Comparison of sensor driven aeration control strategies for improved understanding of simultaneous nitrification/denitrification.

A pilot scale process was operated with A-stage effluent (ASE) and primary clarifier effluent (PCE) in MLE, all tanks aerated, A/O, and A2O configurations. Continuous DO control at high DO (2mg/L), low DO (0.1-0.3mg/L), ammonia-based aeration control (ABAC), and ammonia versus NOx (AvN) control (both continuous and intermittent operation) were compared on the basis of total inorganic nitrogen (TIN) removal, and simultaneous nitrification-denitrification (SND). The highly loaded adsorption/bio-oxidation (A/B) process configuration (4hr HRT) with intermittent aeration was capable of achieving a maximum TIN removal of 80%, while the A2O process with PCE feed, an 11hr HRT, and 0.2-0.3mg/L DO continuous aeration achieved a maximum of 88% TIN removal. ABAC and AvN control did not always result in DO setpoints low enough to achieve SND, and even if setpoints were low enough to achieve SND that did not always result in increased overall TIN removal over continuous DO control of 2mg/L. While there are other benefits to transitioning to sensor driven aeration control strategies such as ABAC and AvN, increased TIN removal during continuous aeration is not guaranteed. Results suggest that although low DO is a prerequisite for SND, carbon availability for denitrification in the aerobic zone is more likely to be the limiting factor once low DO conditions are met. PRACTITIONER POINTS: Intermittent aeration control results in higher TIN removal than continuous aeration at the same total SRT Continuous aeration AvN control is not likely to result in more TIN removal than continuous aeration ABAC for a given COD and nitrogen load Configurations that are designed to maximize predenitrification (e.g., MLE and A2O) are less likely to achieve increased SND in the aerobic zone from low DO operation than configurations that are not (e.g., A/O).

A Unique Variable Selection Approach in Fuzzy Modeling to Predict Biogas Production in Upflow Anaerobic Sludge Blanket Reactor (UASBR) Treating Distillery Wastewater

The upflow anaerobic sludge blanket reactor is known to carry out a complex high-rate anaerobic process used to treat distillery wastewater and is met with many conflicts because of continuous fluctuations in quantity and quality of wastewater, and therefore, it incorporates a lot of uncertainties in operating, controlling and measuring different parameters. In this paper, a multiple-input and single-output fuzzy knowledge-based model was developed to predict biogas production in real-scale upflow anaerobic sludge blanket reactor treating distillery wastewater incorporating seven input variables such as pH (effluent), COD load, COD reduction, temperature, alkalinity-to-acidity ratio, pH (influent) and spent flow rate. Trapezoidal and triangular membership functions were classified to represent the fuzzy sets, and a Mamdani type of fuzzy inference system was used in Matlab fuzzy toolbox. A total of 270 IF–THEN rules have been generated in the fuzzy rule editor using a knowledge-based system. Furthermore, an innovative sequential variable selection approach has been proposed to recognize the most significant parameters in the fuzzy model to predict biogas production which makes the model more practical, manageable and efficient. As a result of the sequential variable selection approach, a combination of five variables such as temperature, COD reduction, COD load, pH(I) and alkalinity-to-acidity ratio has been chosen as the optimal set of variables. The results of the root mean square error and coefficient of determination clearly indicated the better predictive ability of the fuzzy model with the five most important input variables obtained from the sequential variable selection approach than the one with all seven variables.

Fat, oil, and grease (FOG) deposits yield higher methane than FOG in anaerobic co-digestion with waste activated sludge

The formation of fat, oil, and grease (FOG) deposits in sewers is a global challenge for the maintenance of sewer collection systems. Tons of FOG deposits (FDs) are removed from sewer systems every year and present an opportunity for increased methane production via anaerobic co-digestion with waste activated sludge (WAS) at water resource recovery facilities with existing anaerobic digesters. We hypothesized that FDs have higher biomethane potential than that of FOG (e.g., FOG collected in grease interceptors), because of the reduction of inhibition of long chain fatty acids due to saponification. In this study, substantially enhanced methane production was found in anaerobic co-digestion of WAS with FDs within the substrate to inoculum (S/I) ratio range of 0.25–1.2, and the maximum ultimate methane production (685.7 ± 24.1 mL/gVSadded, at S/I = 0.5) was 4.0 times higher than in the control (with WAS only) after 42 days of incubation. Although the lag phase period was longer in FD co-digestion (S/I = 0.5) than in FOG co-digestion (S/I = 0.5) under the same organic loading (gVS) and two times the COD loading, the daily methane production rate became higher after Day 15 in FD co-digestion. Significantly higher cumulative methane production (10.2%, p < 0.05) was obtained in FD co-digestion than in FOG co-digestion after 42-days. Microbial community analysis revealed higher levels of Geobacter in FD co-digestion, possibly suggesting a role for direct interspecies electron transfer (DIET) between Methanosaeta and Geobacter. This work provides fundamental insights supporting anaerobic co-digestion of FDs with WAS, demonstrating the advantages of FDs compared to FOG as co-substrate for enhanced biomethane recovery.

Clean vehicles, polluted waters: empirical estimates of water consumption and pollution loads of the carwash industry

Carwash stations use large volumes of water and release harmful chemicals into the environment through their operations. While a significant body of literature has focused on exploring water use in the carwash industry, none has provided comprehensive information on both the pollution loads of the wastewater emanating from this industry and water consumption. Understanding how much water is used and the pollution loads of wastewater from this industry is useful to ensure adoption of water conservation measures and design wastewater recycling systems given the dwindling freshwater resources globally. This study estimated the freshwater quantities used to wash different vehicle types and the pollution loads of the resulting wastewater in the Kumasi Metropolis. Seven proxy carwash stations were purposively selected and monitored to estimate the water used to wash six different categories of vehicles. Composite wastewater samples from three carwash stations were analysed for concentrations of different contaminants which were used to compute pollution loads. Using R software, one-way ANOVA with Tukey's (HSD) post-hoc testing and 2-sample t-test at 95% confidence interval were employed to test statistical differences. After an 8-week monitoring campaign involving 3,667 vehicles, the study showed that average water used for each vehicle type were in the order: Motorbike - 97L (95% CI: 90–103L); Salon car - 158L (95% CI: 154–161L); SUV - 197L (95% CI:191–203L); Buses/Coaches - 370L (95%CI:351–381L); Articulated truck 1,139L (95% CI:916–1,363L); Graders/Loaders - 1405L (95% CI:327–2,483L). Overall, the carwash industry in the Metropolis uses about 1000m3 of freshwater daily and discharges the resulting wastewater into waterways untreated. The wastewater has a low Biodegradability Index (0.3–0.4) and is characterized by a mildly alkali pH (7.6–8.6) with high levels of Sulphates (40.8–69.8 mg/L), COD (990–1413 mg/L), TSS (1260–3417 mg/L) and E. coli (2.3–4.7 × 103 CFU/100mL). Pollution loads of BOD and COD were up to 2tons/year and 6tons/year respectively. Stipulated effluent discharge guideline values were mostly exceeded – in some cases by up to 68 times. To avert the unbridled wastage of freshwater, the study recommends enforcement of wastewater recycling for all carwash stations and promulgation of a tax system that rewards stations that recycle wastewater and surchages those wasting freshwater.

Fermentation and Effect on the Microbial Loads of Atlantic Cod, &lt;i&gt;Gadus morhua&lt;/i&gt;

The study was carried out to evaluate the effect of fermentation on the microbial loads of Atlantic cod (Gadus morhua). Eviscerated samples of Atlantic cod were fermented in three media: sterile distilled water, 14% saline medium and 14% salt with potash for 24 hours. The fermented Atlantic cod samples were oven-dried at 600C for one hour and thereafter, 1000C for three hours, cooled and stored in plastic baskets at ambient temperature for four weeks. Analyses of the dried fermented Atlantic cod was carried out weekly for Salmonella shigella, total bacterial, Staphylococcal, total fungal and total coliform counts. Results from the mean values indicated variations in the effects of the additives and processing treatments over the 24 hours fermentation period which were significant (p &lt; 0.05). The dressed fish sample fermented with both salt and potash (DRSFP), recorded the least mean microbial counts during the 4-week storage period, followed by the sample which was fermented with salt (DRSF) while the highest occurrence of microorganisms was recorded in the sample which was fermented with sterile distilled water (DRF). Hence, fermentation of fish with salt and potash is recommended. Meanwhile, in relation to the standard recommended microbial limits, the loads of microbes on the fermented Atlantic cod samples from the three treatments still fall within the safe and acceptable level.&#x0D; Keywords: Gadus morhua, Fermentation, Salt, Potash, Microbial load

Synthesis of Formaldehyde Free Amino Resin to Produce Green Eco-Labelled Leather with Improved Retanning Properties

Formaldehyde has many applications in the chemical industry including synthesis of amino resins which are used in leather processing. After application in leather, these resins are hydrolyzed under certain conditions to release free formaldehyde which has high environmental concerns due to its proven carcinogenic effects. The objective of this work is to develop a formaldehyde free melamine-based resin to produce green leather with improved retanning properties and thermal stability. The optimum melamine resin was synthesized by condensing melamine with glyoxal instead of formaldehyde. Further, the water solubility and improved thermal stability of synthesized melamine resins were achieved by introduction of sulfanilic acid in resin structure. Synthesized resin was used in leather retanning in comparison with commercially available melamine resin as a control. Both leathers were tested for mechanical properties, organoleptic properties, grain surface and fiber structure analysis. Comparative free formaldehyde content was measured in resultant leathers. Effluents of retanning baths were comparatively analyzed. Optimum resin was also characterized by thermo gravimetric analysis and FTIR. The results of this study showed that the experimental resin has imparted significant improvement in mechanical and organoleptic properties of leather as compared to the control resin. Analysis of free formaldehyde content confirmed the absence of free formaldehyde in leather treated with optimum resin while 141 mg/kg formaldehyde was detected in leather treated with control resin. Free formaldehyde was also absent in effluent of experimental resin while 305 mg/kg formaldehyde was detected in effluent of control resin. Moreover, percentage efficiency in COD, TDS and TSS load of effluent was observed as 9.62, 7.2 and 6.31 respectively. Resultant leather was free from formaldehyde making it safe for human along with reduction in pollution load of tannery.

High methanogenic activity of a three-stage UASB in relation to the granular sludge formation

A new UASB (upflow anaerobic sludge blanket) system with three-stage concept and granular sludge formation was developed to provide a very high process activity, in terms of a high energy yield and a large optimum COD loading rate, from ethanol wastewater at 37 °C and a controlled pH of 5.5 in the first bioreactor with recirculation of the final overflow from the third to the first two bioreactors to lower the amount of sodium hydroxide used for pH control in the first bioreactor and to increase the total alkalinity of the whole system. The proper volumetric ratio of the three-stage UASB with flocculant sludge provided the dominance of the three sequencial steps of acidogenesis, acetognesis and methanogenesis to occur in the respective bioreactors, causing a higher process performance and giving the optimum COD loading rate of 15 kg/m3d. The presence of granular sludge in all three bioreactors, resulted from the slow increment in the COD loading rate over a long operation period with high levels of microbial concentrations in all three bioreactors under the continuous feed operation and steady sate condition. This further increased the optimum COD loading rate from 15 to 25 kg/m3d (calculated from the total liquid volume) with an extremely high energy yield of 11,740 kJ/kg COD applied.

Rapid degradation of 2,4-dichloronitrobenzene in single-chamber microbial electrolysis cell with pre-acclimated bioanode: A comprehensive assessment

2,4-dichloronitrobenzene (DClNB) as a typical refractory pollutant, exists in multifarious industrial wastewater widely and poses a serious threat to the environment. An ion exchange membrane (IEM)-free microbial electrolysis cell (MEC) with pre-acclimated bioanode was built and evaluated systematically for treatment of DClNB containing wastewater. Results showed that compared with the non-acclimated or IEM-equipped MECs, the pre-acclimated IEM-free MECs had the best DClNB removal efficiency of 91.3% under COD and DClNB loading rates of nearly 1000 kg m−3 d−1 and 100 g m−3 d−1. Both of anode pre-acclimation and IEM removal reduced the electron transfer resistance by 71.1 and 194.5 Ω, respectively. Compared to the pre-acclimated IEM-equipped MEC, the cathode current efficiency of pre-acclimated IEM-free MEC increased by 13.7%. Analysis of live/dead cell staining indicated that a higher proportion of live cells was observed in the acclimated anode biofilm (66.1% vs. 47.3%), and the detoxification of DClNB in the pre-acclimated IEM-free MECs was significantly better (p < 0.05) than those of non-acclimated or IEM-equipped MECs. This study contributes to the performance improvement of the MEC process for treatment of toxic industrial wastewater.

The Relationship of Different COD Concentration, Sediment Pollutant Content with Hydrodynamic in Black Bloom Water Based on Stepwise Regression Method

To analyze the relationship of different COD concentration, sediment pollutants with hydrodynamic. Taking a polluted river as the research object, the data of flow velocity, water temperature, COD concentration, sediment OM content, sediment TN content and sediment TP content at nine sampling points were analyzed by stepwise regression and SPSS 25 data analysis software. Construct linear regression model of COD concentration Y, river flow velocity X1, water temperature X2, sediment OM content X3, sediment TN content X4, sediment TP content X5. The regression equation Y=106.172-64.304X4 + 0.065X5 with correlation coefficient R=0.954 and determination coefficient R2=0.91 was obtained by stepwise regression method. The results showed that the concentration of COD in water was correlated with the content of nitrogen and phosphorus in river sediments, and negatively correlated with the content of TN and positively correlated with the content of TP. The model can be used to estimate COD load of water body by analyzing the nitrogen and phosphorus content in river sediments.