Biological Oxygen Demand Removal Research Articles

Effect of variable salinity wastewater on performance and kinetics of membrane‐based bioreactors

AbstractBACKGROUNDA membrane bioreactor and two hybrid moving bed biofilm reactor‐membrane bioreactor systems were operated in parallel for the treatment of variable‐salinity wastewater. Influent salinity was changed according to tidal‐like cycles: 6 h of maximum salinity (4.5 or 8.5 mS cm−1) followed by 6 h of regular wastewater salinity (around 1 mS cm−1).RESULTSFor the two salinity scenarios, the bioprocesses operated under different conditions of mixed liquor total suspended solids (2500 and 3500 mg L−1), and hydraulic retention time (6, 9.5 and 12 h). The results showed that the bioprocesses had better performance under 4.5 mS cm−1 than under 8.5 mS cm−1 in terms of removal of biological oxygen demand at day 5 (BOD5) (+6.07%), ammonium cation (NH4+) (+41.29%) and total nitrogen (+37.64%), the heterotrophic and autotrophic yield coefficients (+0.02777 mgVSS mgCOD−1 and +0.13990 mgVSS mgN−1), and the autotrophic rate of substrate utilization (+3.39559 mgN L−1 h−1).CONCLUSIONSThe results obtained would become of help for the modeling of membrane‐based systems treating variable saline wastewater. © 2019 Society of Chemical Industry

Application of a downflow microaerophilic fixed film (DFMFF) reactor for the treatment of dye house effluents using a developed bacterial consortium

The present study describes a downflow microaerophilic fixed film (DFMFF) reactor based treatment of dye house effluents. The major characteristics of the two effluents E-2 and E-5 under study were; chemical oxygen demand (COD) 4680-16,266 mg L−1, biological oxygen demand (BOD) 1575–3151 mg L−1 and American Dye Manufacturers' Institute (ADMI) color index of 10,794–21,413. DFMFF reactor was packed with ultra-high molecular weight polyethylene (UHMWPE) shredding. The developed consortium was allowed to grow and form bio-film on packed UHMWPE. Degradation of the effluents at a various hydraulic retention time (HRT) and organic loading rate (OLR) was studied. Batch mode studies in the reactor showed > 80% removal of BOD and COD at OLR of 4.3 kg L−1 day−1 of E-2 and 2.4 kg L−1 day−1 of E-5 at 48 h HRT. Fourier Transform Infrared Spectroscopy (FTIR) and High Performance Liquid Chromatography (HPLC) analysis confirmed biodegradation and obtained results indicated significant induction of oxidoreductive enzyme activities of azoreductase, NADH–DCIP reductase and laccase enzymes. Reduction in phytotoxicity and microbial toxicity was observed after the treatment of both the effluents. The reactor was also operated on continuous mode for treatment of E-2 under sequential anaerobic–aerobic phase and charcoal treatment. Results of sequential effluent treatment resulted in a reduction of > 99% of COD, BOD and ADMI along with > 88% of solids removal from the effluent. The resulting effluent was clear and meets the discharge criteria so as to release into the sewers. .

A modified upflow anaerobic sludge blanket reactor as an alternative for decentralized domestic wastewater treatment in developing countries

AbstractThe aim of this paper was to evaluate the performance of two modified upflow anaerobic reactor (RAns) as a decentralized technology for the treatment of high-strength domestic wastewater. Two full-scale anaerobic reactors (Ran1 and Ran2) with the same configuration and total volume of 14.6 m³, total height of 2.57 m, and constructed from fibreglass reinforced plastics were operated with a 16-hour hydraulic retention time and submitted to a volumetric organic load less than 2.7 kg chemical oxygen demand (COD)·m−3·d−1. The RAns were monitored for 10 consecutive months and showed the capability to support the fluctuations of organic loading and volumetric rates. The compact anaerobic reactors proved to be effective in removing organic matter (biological oxygen demand removal efficiencies greater than 70% and the average soluble COD removal efficiencies greater than 57.4%). The solids profile in the reactor ranged from very dense particles with good settleability close to the bottom (sludge bed) to a more dispersed and light sludge close to the top of the reactor (sludge blanket), similar to conventional UASB reactors.

Field analysis of PSA O2–ozone production process for water recycling

AbstractThe use of an oxygen generator based on pressure swing adsorption technology (PSA) has been investigated as an alternative method for supplying oxygen for onsite ozone production. During the investigation period of 1040 h, the oxygen purity from the PSA process fluctuated within a range of 90.5–93 O2% (v/v). Using the working ratio of 2.8 mol of O2 to 1 m3 of raw water, the PSA process in series with a corona discharge ozone generator yielded an oxidation–reduction potential of ca. 200 mV and a concentration of 22.8 mg/L dissolved oxygen. The average efficiency of the raw water treatment was as follows: 47% chemical oxygen demand removal, 78% biological oxygen demand removal, 36% sulphide removal and 34% colour removal. The operating cost of the PSA O2 generation was reduced 3 times compared with the cost of high‐pressure oxygen cylinders.

Removal of Anionic Surfactant from Residential Laundry Wastewater using Jackfruit (Artocarpus heterophyllus) seeds

The study presented in this article investigated the removal of a long chain anionic surfactant from residential laundry wastewater using jackfruit (Artocarpus heterophyllus) seeds. The main ingredients of laundry wastewater are the surfactants. Therefore, great attention should be given to the treatment and disposal of laundry wastewater. The use of natural substitutes in treating wastewater has no harmful effects, and it is considered an effective step towards protecting the environment and promoting sustainability. Jar test experiments were conducted in order to determine the optimum conditions for the removal of surfactants, chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity in terms of effective dosage, and pH control. The surfactant, COD, BOD, and turbidity removal efficiencies were 91.66%, 82.86%, 77.66%, and 85.14% at the optimum initial pH value of 6, the optimum dose of 2.5 g/L, and optimum mixing time of 25 minutes, respectively. It can be concluded that Artocarpus heterophyllus seed powder was a feasible and cost-effective natural coagulant for the removal of anionic surfactant from laundry wastewater. The results showed that the pseudo-second-order equation is the suitable model for this system.

Response Surface Methodology for removal of Biological Oxygen Demand (BOD) through RBC

Response Surface Methodology for removal of Biological Oxygen Demand (BOD) through RBC

Novel biofilm reactor for denitrification of municipal wastewater.

A pilot-scale CFIC® (continuous flow intermittent cleaning) reactor was run in anoxic conditions to study denitrification of wastewater. The CFIC process has already proven its capabilities for biological oxygen demand removal with a small footprint, less energy consumption and low cost. The present study focused on the applicability for denitrification. Both pre-denitrification (pre-DN) and post-denitrification (post-DN) were tested. A mixture of primary treated wastewater and nitrified wastewater was used for pre-DN and nitrified wastewater with ethanol as a carbon source was used for post-DN. The pre-DN process was carbon limited and removal rates of only 0.16 to 0.74 g NOx-N/m²-d were obtained. With post-DN and an external carbon source, 0.68 to 2.2 g NO3-Neq/m²-d removal rates were obtained. The carrier bed functioned as a good filter for both the larger particles coming with influent water and the bio-solids produced in the reactor. Total suspended solids removal in the reactor varied from 20% to 78% (average 45%) during post-DN testing period and 9% to 70% (average 29%) for pre-DN. The results showed that the forward flow washing improves both the DN function and filtration ability of the reactor.

Development of platinum supported on single-walled carbon nanotubes by deposition-precipitation for microbial fuel cells.

Microbial fuel cells (MFCs) are an ecologically friendly technology that can recover electricity and simultaneously treat wastewater. Among all the influential factors, cathode material and catalyst play a crucial role in electricity production and oxygen reduction. In this study, Pt nanocatalysts deposited on single-walled carbon nanotubes (Pt/SWCNTs) were synthesized by the deposition-precipitation (DP) method under optimal conditions. The results show that DP might be a promising method for the preparation of Pt/SWCNTs due to its simple, cost-effective and time-saving procedure, in addition to being highly efficient at creating small Pt particles (0.9 nm) that were very uniformly distributed. The synthesized Pt/SWCNTs suspension was spray-coated on to carbon cloth and then used as a cathode for MFCs. The electricity generation of MFCs equipped with a Pt/SWCNTs cathode was evaluated in terms of open circuit voltage (0.6954 V), internal resistance (63.3 Ω•m2) and maximum power density (2,022 mW/m2). The chemical oxygen demand removal, biological oxygen demand removal, total dissolved solids removal, total suspended solids removal and silver recovery was satisfactory at 84.5%, 74.0%, 45.7%, 60.0% and 99.0%, respectively. Therefore, Pt/SWCNTs from the DP method was identified as a potential candidate to replace commercial Pt-carbon cloth for MFC cathodes.

Coagulant from Leucaena leucocephala for Chromium Removal

This research investigated the effectiveness of leucaena leucocephala as a natural coagulant for chromium removal. Leucaena leucocephala is a permanent non-climbing shrub tree which is wild and abundant in Malaysia and commonly known as petai belalang. Coagulation experiment using jar test were performed where the effect of coagulant dosage and pH were examined. The parameters investigated were suspended solid (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity and chromium content. The optimum of leucaena leucocephala coagulant dosage for removal of suspended solid, turbidity, COD, BOD and Chromium is at range 400-600 mg/L which yielded 45, 31.4, 38.5, 27.5 and 4.05% removal respectively. While the optimum pH is at pH 2-4 (acidic) which give 33.3, 26.8, 33.75, 31.4 and 14.06% removal of suspended solid, COD, BOD, turbidity and chromium content respectively. It is concluded that the leucaena leucocephala showed tremendous potential for chromium removal.

Marsilea quadrifolia: a New Bioagent for Treating Wastewater

We report for the first time the capability of four-leaf clover (Marsilea quadrifolia), a wetland plant which grows rooted in soil, in efficiently treating sewage. The use of M. quadrifolia was made possible because of the special attributes of the SHEFROL® (SHEet Flow ROot Level) bioreactor in which it was employed. This bioreactor enables the use of free-floating aquatic plants as well as terrestrial and rooted-in-soil wetland plants by hydroponics. The plants are staked in narrow channels to enable them to support each other while sewage is made to flow rapidly as a sheet of wastewater at a level that covers only the plant roots (hence the name). It was seen that M. quadrifolia was able to treat sewage of strength varying in the chemical oxygen demand (COD) range of 600–1800 mg/L to the extent of > 80% at a hydraulic retention time (HRT) of just 4.5 h. There was a near total removal of biological oxygen demand and suspended solids while total Kjeldahl nitrogen, soluble phosphorous, and heavy metal zinc were also substantially removed. The macrophyte was equally effective when used indoors under artificial lighting, as well as when used outdoors.

Sequestering of pollutants from public market wastewater using Moringa oleifera and Cicer arietinum flocculants

The present study aimed to investigate potential of Moringa oleifera and Cicer arietinum seeds for the treatment of public market wastewater in comparison to Alum and FeSO4. The flocculation process was assessed as a function of adsorbent dose (60–360 mg/L), pH (4 to 9) and mixing rate (50 to 300 rpm). The adsorption study was performed to find out the removal of biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), oil and grease (O&G), colour, and turbidity in a lab-scale plant system (6 L). The results revealed that the use of M. oleifera resulted in the highest removal for BOD5, COD and O&G (68.08%, 79.1% and 83.3% respectively) at 180 mg/L, pH 7 to 8, and a mixing rate of 150 rpm. The use of Alum resulted in the highest removal percentage for TSS, colour and turbidity (87.17, 90.83 and 81.06% respectively) at 120 mg/L, pH 7 to 8, and a mixing rate of 150 rpm. The Langmuir adsorption isotherm was the best model for the removal of turbidity by M. oleifera and C. arietinum (R2 = 0.91 and 0.93) compared to the Freundlich model (R2 = 0.81 and 0.82). Moreover, the adsorption of COD (R2 = 0.91) by M. oleifera was fitted to both the Langmuir and Freundlich isotherms. In contrast, the Freundlich isotherm was the best for studying the removal of COD (R2 = 0.96) and O& G (R2 = 0.99) by C. arietinum. The findings obtained indicated that natural coagulants are applicable for improving the quality of public market wastewater.

Development of the “French system” vertical flow constructed wetland to treat raw domestic wastewater in India

The main aim of our study was to construct a two-stage vertical flow constructed wetland (VFCW) system to treat single household raw sewage water in India under tropical climate. For selecting the plant species different sets of lab experiments were carried out. Two different plant species (Typha angustata and Canna indica) were considered for their nutrient removal efficiency and biochemical methane potential (BMP) efficiency. Drum experiments were conducted to select the most suitable species for the constructed wetland. Batch assays were conducted in 100 ml bottles in order to determine BMP of plant biomass. The overall nutrient removal efficiency was the same in case of both the plant species that were tested. Typha angustata had been selected for planting in the single household wetland system as it is found in the natural wetlands of Goa and they have higher BMP than other species. The nutrient removal of pilot scale VFCW was monitored at two hydraulic loadings at 0.150 m/day and at 0.225 m/day. The removal of Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Kjeldahl Nitrogen (TKN), Ammoniacal Nitrogen (NH3-N), Total Phosphorous (TP), Total Dissolved Solid (TDS) and Total Volatile Solids (TVS) at 1st stage was 64%, 65%, 15%, 21%, 34% and 54% and for the 2nd stage reactor it is 90%, 88%, 50%,52%, 58% and 71% respectively on an average. After changing HLR (hydraulic loading rate) to 0.225 m/day the removal of COD, BOD, TDS, TVS, TKN and NH3-N at 1st stage was 61%, 62%, 33%, 40%, 35% and 58% and for the 2nd stage reactor it is 90%, 84%, 61%, 64%, 47% and 82% respectively on an average. As the loading rate increases there is no change in the treatment efficiency of TKN and NH3-N treatment efficiency increases. However marginal decrease in the treatment efficiency of COD and BOD of the system was observed. The overall footprint of the system got reduced from 1.5 m2 per person to 0.79 m2 per person under Goan climatic conditions.

Treatment of compost leachate by ferro-sonication process: Effect of some operational variables

Aim: Application of composting process for the management of organic solid waste led to the production of leachate, which causes many problems to environment. This study was aimed at investigation of ferro-sonication (FS) process in composting leachate degradation. Materials and Methods: Leachate samples were collected in composting factory located in Isfahan. In each run, 400 ml of leachate was sonicationed through an ultrasonic homogenizer in a cylindrical glass reactor. Ferrous sulfate was added to the reactor as accelerator agent. The effect of various parameters including pH, ferrous sulfate doses, sonication times, and ultrasonic intensity was studied in the removal of chemical oxygen demand (COD) and biological oxygen demand (BOD) from composting leachate. Results: The results showed that the COD and BOD removal rate was increased by increasing ferrous sulfate dosages, sonication time, and ultrasonic intensity. In addition, lower pH was favored for leachate degradation. In general, the optimum conditions for pH, ferrous sulfate dosage, irradiation time, and ultrasonic intensity were 3, 8 mmol, 180 min, and 150 W, respectively. Approximately 46% of COD and 33% of BOD were removed in optimum condition. Conclusion: These results revealed that FS can be effective in degradation of compost leachate and can be presented as a good choice for pretreatment of leachate.

Decolorization and detoxification of dye mixture and textile effluent by lichen Dermatocarpon vellereceum in fixed bed upflow bioreactor with subsequent oxidative stress study

Navy Blue HE22 (NBHE22), dye mixture and real textile effluent were decolorized and degraded by lichen Dermatocarpon vellereceum. Up-flow bioreactor showed about 80%, 70%, 80% and 65% removal of American dye manufacturer index (ADMI), biological oxygen demand (BOD), total suspended solids (TSS) and total dissolved solids (TDS), respectively of dye mixture at flow rate of 25mlh−1. The removal of ADMI, BOD, TSS and TDS of real textile effluent were 75%, 65%, 82% and 70%, respectively at flow rate of 30mlh−1. Significant induction of extracellular enzymes such as manganese peroxidase and lignin peroxidase was observed up to 46% and 36% during decolorization of dye mixture, while 43% and 24% during effluent treatment, respectively. Exponential enhancement in the activities of stress enzymes such as catalase (CAT) and guaiacol peroxidase (GPX) was observed after exposure to NBHE22 (116% and 125%, respectively), dye mixture (150% and 300%, respectively) and effluent (400% and 350%, respectively) endorsing the stress tolerance ability of model lichen. Phytotoxicity and genotoxicity studies demonstrated less toxic nature of metabolites resulted from biodegradation.

Biodegradation of dairy wastewater using bacterial and fungal local isolates.

Dairy wastewater contains high levels of organics and other pollutants. The present study was carried out to investigate the biodegradation process of dairy effluents using some locally isolated bacteria and fungi. Four different dairy effluent samples were collected from Obour and 6th October industrial cities, Egypt. Five bacterial species (Pseudomonas aeruginosa, Bacillus subtilis, Lactobacillus delbrueckii, Staphylococcus aureus and Enterococcus hirae) and three fungal strains (Alternaria sp., Fusarium sp. and Aspergillus sp.) were isolated from dairy wastewater samples, identified and used for biodegradation process. Bacterial and fungal consortia were prepared separately in the laboratory. Two-stages (aeration and filtration) laboratory scale model was designed. Rice straw and activated carbon layers were used as filtration media. Results indicated the great ability of both studied bacteria and fungi for removal of organics (biological oxygen demand removal percent were 78.7% and 74.7% for bacteria and fungi, respectively) and the improvement of the physicochemical quality (total suspended solids removal percent were 99.3% and 99.0% for bacteria and fungi, respectively) of the dairy effluent. The addition of rice straw and activated carbon increased removal efficiencies. Biodegradation of dairy wastewater depending on local microorganisms is an effective, cheap and eco-friendly technology.

Adsorption studies on the removal of COD and BOD from treated sewage using activated carbon prepared from date palm waste.

In this work, the adsorption of chemical oxygen demand (COD) and biological oxygen demand (BOD) from treated sewage with low-cost activated carbon prepared from date palm shell waste by chemical activation method was studied. Different parameters affecting the adsorption process such as carbon dose, pH, contact time, agitation rate, and temperature were studied. Adsorption equilibrium was attained after 150min at pH 6.0 with agitation rate of 400rpm at 25°C. The results showed that COD removal percentage of 95.4 and 92.8% for BOD was obtained with carbon dosage of 0.1g/100ml of solution. The experimental batch equilibrium results follow linear, Langmuir, and Freundlich isotherm models. The experimental data was fitted to a pseudo-second-order kinetics model controlled by pore diffusion. Thermodynamic parameter values of ΔH 0, ΔG 0, and ΔS 0 were calculated. The obtained data indicated that the adsorption was spontaneous, endothermic nature and reflects an increased randomness and degree of disorderliness at the activated carbon/sewage interface during the adsorption process investigated in this study. Concentrations of different impurities were reduced to very small value by investigated adsorption process.

Effect of intermittent aeration strategies on treatment performance and microbial community of an IFAS reactor treating municipal waste water

ABSTRACTThis study investigated the effect of various intermittent aeration (IA) cycles on organics and nutrient removal, and microbial communities in an integrated fixed-film activated sludge (IFAS) reactor treating municipal waste water. Average effluent biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids, total nitrogen (TN) and total phosphorus (TP) values were noted as 20, 50, 30, 12 and 1.5 mgL-1, respectively, in continuous aeration mode. A total of four operational conditions (run 1, continuous aeration; run 2, 150/30 min aeration on/off time; run 3, 120/60 min aeration on/off time and run 4, 90/60 min aeration on/off time) were investigated in IFAS reactor assessment. Among the all examined IA cycles, IA phase 2 gave the maximum COD and BOD removals with values recorded as 97% and 93.8%, respectively. With respect to nutrient removal (TN and TP), IA phase 1 was found to be optimum. Pathogen removal efficiency of present system was recorded as 90-95% during the three phases. With regard to settling characteristics, pilot showed poor settling during IA schedules, which was also evidenced by high sludge volume index values. Overall, IA could be used as a feasible way to improve the overall performance of IFAS system.

Designing and construction of simulated constructed wetland for treatment of sewage containing metals

ABSTRACTA simulated horizontal flow constructed wetland (CW) has been designed with gravel medium and aquatic plants Typha latifolia and Polygonum hydropiper to assess its performance efficiency for sewage treatment. Monitoring of fully developed CW revealed a high removal of nutrients and metals from sewage after treatment at varying retention times. The percent (%) removal of biological oxygen demand, total dissolved solids, total suspended solids, PO4-P and total nitrogen in CW planted with T. latifolia were 88.20, 61.9, 72.12, 74.23 and 66.78%; however, with P. hydropiper, reductions were 79.47, 53.47, 55.46, 60.40 and 52.87%, respectively, at 8 d retention time. In addition, T. latifolia and P. hydropiper accumulated substantial amount of metals in their tissues particularly in roots. T. latifolia root accumulated maximum amount of Zn (40.44 µg/g dw) followed by Cu (39.24 µg/g dw), Pb (37.78 µg/g dw) and Cr (19.95 µg/g dw) as compared to P. hydropiper, which was 17.85, 33.43, 36.19 and 9.67 µg/g dw, respectively. Further, plant-specific high translocation factor (>1) of metals were observed at different retention times. Results suggest that simulated CW may be applied as an ecofriendly and low-cost tool to treat sewage before discharge into a fresh water body.

Rapid adaptation of activated sludge bacteria into a glycogen accumulating biofilm enabling anaerobic BOD uptake

Glycogen accumulating organisms (GAO) are known to allow anaerobic uptake of biological oxygen demand (BOD) in activated sludge wastewater treatment systems. In this study, we report a rapid transition of suspended activated sludge biomass to a GAO dominated biofilm by selective enrichment using sequences of anaerobic loading followed by aerobic exposure of the biofilm to air. The study showed that within eight weeks, a fully operational, GAO dominated biofilm had developed, enabling complete anaerobic BOD uptake at a rate of 256mg/L/h. The oxygen uptake by the biofilm directly from the atmosphere had been calculated to provide significant energy savings. This study suggests that wastewater treatment plant operators can convert activated sludge systems readily into a “passive aeration” biofilm that avoids costly oxygen transfer to bulk wastewater solution. The described energy efficient BOD removal system provides an opportunity to be coupled with novel nitrogen removal processes such as anammox.

Treatment of tannery effluent using sono catalytic reactor

The effluent released from the leather process industries contain high amount of chemical oxygen demand (COD), biologicaloxygen demand (BOD), suspended solid (SS), ammonia nitrogen, Total Kejeldahl Nitrogen, nitrate, nitrogen, hexavalent and trivalent chromium, chloride, sulphates, etc. In the present study the lime pre-treated effluent is exposed to a sonocatalytic reactor, in which the TiO2 catalyst was used. The parameters such as BOD, COD and total dissolved solids (TDS) were studied by varying the concentration of effluent, time and catalyst load. The results reveal that the efficiency of sono catalytic reactor on percentage removal of COD, BOD and TDS were 89.53, 87.35 and 92.63 respectively. The response surface methodology (RSM) was used to optimize the variables such as catalyst loading and time. Statistical results were assessed with various descriptive such as p value, lack of fit (F-test), coefficient of R2 determination. The predicted and adjusted R2 values were found to be 0.9956, 0.9673 for% COD removal, 0.9484, 0.9926 for% BOD removal and 0.9980, 0.9954 for% TDS removal respectively.