Biokinetic Coefficients Research Articles

Nickel augmented biochar for sustaining produced water treatment to decarbonize oil and gas industrial waste using anaerobic-aerobic granular cylindrical periodic discontinuous batch reactors

This study assessed the efficacy of granular cylindrical periodic discontinuous batch reactors (GC-PDBRs) for produced water (PW) treatment by employing eggshell and waste activated sludge (WAS) derived Nickel (Ni) augmented biochar. The synthesized biochar was magnetized to further enhance its contribution towards achieving carbon neutrality due to carbon negative nature, Carbon dioxide (CO2) sorption, and negative priming effects. The GC-PDBR1 and GC-PDBR2 process variables were optimized by the application of central composite design (CCD). This is to maximize the decarbonization rate. Results showed that the systems could reduce total phosphorus (TP) and chemical oxygen demand (COD) by 76–80% and 92–99%, respectively. Optimal organic matter and nutrient removals were achieved at 80% volumetric exchange ratio (VER), 5 min settling time and 3000 mg/L mixed liquor suspended solids (MLSS) concentration with desirability values of 0.811 and 0.954 for GC-PDBR1 and GC-PDBR2, respectively. Employing four distinct models, the biokinetic coefficients of the GC-PDBRs treating PW were calculated. The findings indicated that First order (0.0758–0.5365) and Monod models (0.8652–0.9925) have relatively low R2 values. However, the Grau Second-order model and Modified Stover-Kincannon model have high R2 values. This shows that, the Grau Second Order and Modified Stover-Kincannon models under various VER, settling time, and MLSS circumstances, are more suited to explain the removal of pollutants in the GC-PDBRs. Microbiological evaluation demonstrated that a high VER caused notable rises in the quantity of several microorganisms. Under high biological selective pressure, GC-PDBR2 demonstrated a greater percentage of nitrogen removal via autotrophic denitrification and a greater number of nitrifying bacteria. The overgrowth of bacteria such as Actinobacteriota spp. Bacteroidota spp, Gammaproteobacteria, Desulfuromonas Mesotoga in the phylum, class, and genus, has positively impacted on granule formation and stability. Taken together, our study through the introduction of intermittent aeration GC-PDBR systems with added magnetized waste derived biochar, is an innovative approach for simultaneous aerobic sludge granulation and PW treatment, thereby providing valuable contributions in the journey toward achieving decarbonization, carbon neutrality and sustainable development goals (SDGs).

Unlocking the potential of Chlamydomonas sp. for sustainable nutrient removal from POME: A biokinetic investigation

This study aimed to assess the capability of Chlamydomonas sp., for the treatment of palm oil mill effluent (POME), with a particular focus on nutrient removal efficacy. Batch cultivation experiments were conducted using Chlamydomonas sp. in bold basal medium (BBM) with varying POME concentrations. Biokinetic coefficients for nutrient removal were determined using the Michaelis-Menten equation. Over 16 days, Chlamydomonas sp. efficiently removed 100 % of ammonium (NH4+) and nitrate (NO3−), 66–89 % of phosphate (PO43−), and 16.7–33.2 % of chemical oxygen demand (COD). Experimental results and biokinetic coefficients highlighted the superior removal of NH4+ and PO43− by Chlamydomonas sp. in POME. For NH4+, the determined coefficients were k = 3.7161 mg NH4+ mg−1 DCW d−1, Km = 217.97 mg L−1, YN = 17.64 mg DCW mg−1 NH4+. For PO43−, the coefficients were k = 2.5413 mg PO43− mg−1 DCW d−1, Km = 131.53 mg L−1, YP = 12.91 mg DCW mg−1 PO43−. Chlamydomonas sp. biomass performed exceptionally well under low NH4+ and PO43− concentrations, requiring minimal nutrient input compared to COD and NO3−. In conclusion, Chlamydomonas sp. shows promise as an efficient and sustainable option for nutrient removal from POME and other wastewater sources, particularly those containing high levels of nitrogen and phosphate.

The best location for the application of static magnetic fields based on biokinetic coefficients in complete-mix activated sludge process

The use of the kinetic coefficients for the mathematical expression of the biochemical processes and the relationship between the effective parameters is importance. Change of the biokinetic coefficients in the complete-mix activated sludge processes were calculated for 1 month operation of the activated sludge model (ASM) in a Lab-scale in three series. 15 mT intensity of static magnetic fields (SMFs) applied on the aeration reactor (ASM 1), clarifier reactor (ASM 2) and, sludge returning systems (ASM 3) for 1 h, daily. During the operation of the systems, five basic biokinetic coefficients such as maximum specific substrate utilization rate (k), heterotrophic half-saturation substrate concentration (Ks), decay coefficient (kd), yield coefficient (Y) and, maximum specific microbial growth rate (μmax) were determined. The rate of k (g COD/g Cells.d) in ASM 1 was 2.69% and, 22.79% higher than ASM 2 and, ASM 3. The value of Ks (mg COD/L) was 54.44 and, 71.13 (mg/L) lower than the ASM 2 and, ASM 3. The rate of kd ASM 1, ASM 2 and, ASM 3 was 0.070, 0.054 and, 0.516 (d−1). The value of Y (kg VSS/kg COD) in ASM 1 was 0.58% and, 0.48% lower than ASM 2 and, ASM 3. The rate of μmax (d−1) in ASM 1 was 0.197, this value for ASM 2 and ASM 3 were 0.324 and 0.309 (d−1). Related to the biokinetic coefficients analyses the best location for the application of 15 mT SMFs was the aeration reactor, where the present of oxygen, substrate and, SMFs have the greatest impact on the positive changes of these coefficients.

Determination of biokinetic coefficients of an aerobic system for potato starch removal

This study presents an aerobic laboratory scale-reactor completely mixed performance for starch wastewater treatment. The reactor was operated for 119 days divided into 5 operational phases which included the start-up and the variation of cell-residence time. In order to determine the biokinetic coefficients for starch removal, the cell-residence time was varied between 20 to 4 days, and the system operation was set hydraulic retention time of 24 hours with a completely mixed reactor setup. The chemical oxygen demand concentration was 1000mg/L in the inflow of the reactor and dissolved oxygen remained above 2mg/L. In this experimentation time, the parameters such as pH, chemical oxygen demand (in the influent and effluent), dissolved oxygen and Mixed liquor suspended solids were monitored. The calculation of biokinetic constants was done by an approximate method, using the graphical Lineweaver-Burk method. The biokinetic coefficients determined were for Maximum substrate removal rate , Half saturation rate constant or affinity constant ( sludge yield coefficient (Y), and Microbial decay or indigenous respiration rate . The results showed that Y, , and ( were in the range of 0,3- 0,7 mgSSV/mgBOD5, 2- 8 Day1 and 40-120 mg/L (COD- BOD5), respectively. Values of the coefficients were within the range of those reported for conventional activated sludge processes.

Investigation, biokinetic calculation, and modelling of a real combined industrial wastewater biological treatment process by activated sludge models

Background: Treatment of combined industrial wastewater from industrial parks is one of the most complex and difficult wastewater treatment processes. Also, the accuracy of biological models for the prediction of the performance of these processes has not been sufficiently evaluated. Therefore, in this study, the International Association on Water Quality (IAWQ(-Activated Sludge Model No. 1 (ASM1) was implemented for the Jey industrial park in Isfahan province, Iran. Methods: The Jey IPWWTP process is a combination of anaerobic and aerobic biological processes. To evaluate the overall performance of IPWWTP, organic compounds, suspended solids, nutrients, attached biomass, and some operating parameters were measured during 6 months. Then, the biokinetic coefficients of aerobic processes were determined using Monod equations. Finally, the aerobic processes were modeled using ASM1 implemented in STOAT software. Results: The values of the biokinetic coefficients K, Y, Ks, Kd, and µmax were calculated as 2.7d- , 0.34 mg VSS/mg COD, 133.36 mg/L COD, 0.03d- , and 0.93d- , respectively. Based on the default coefficients and conditions of the ASM model, the difference between the experiments and model prediction was about 2 to 98%. After calibrating the ASM model, the difference between the experiments and prediction in all parameters was reduced to less than 10%. Conclusion: Investigations showed that the default coefficients and operation conditions of the ASM1 model do not have good predictability for complex industrial wastewaters and the outputs show a low accuracy compared to the experiments. After calibrating the kinetic coefficients and operating conditions, the model performance is acceptable and the predictions show a good agreement with the experiments.

Kinetic Study for Startup of Aerobic Moving Bed Biofilm Reactor in Treatment of Textile Dye Wastewater.

Due to high augmentation in population and low availability of land, the quantum of wastewater production has surged resulting in advancements in wastewater treatment systems. To cope under such stressful circumstances, moving bed biofilm reactor (MBBR) proves to be an upgraded treatment technology for industrial and municipal wastewater treatment. The present startup study has been carried out using a laboratory-scale aerobic MBBR with working volume of 25L for textile dye wastewater treatment having AnoxKaldnes K3 media at filling percentage of 50%. In order to acclimatize the microorganisms on textile dye wastewater, the startup of the reactor was carried out using lactose as readily degradable co-substrate with textile dye wastewater in different ratios at hydraulic retention time (HRT) of 24h. The biofilm on the media was developed in 63days duration and the reactor attained pseudo-steady state (PSS) in 185days period. During PSS condition of the MBBR, the maximum chemical oxygen demand (COD) removal efficiency of 92% with mixed liquor suspended solids (MLSS) concentration of 4224 ± 22mg/L has been achieved. The kinetic study for biodegradation of textile dye wastewater has also been carried out using the Monodgrowth kinetics. The values of bio-kinetic coefficients of yieldof heterotrophic biomass (Y) and endogenousdecay coefficient for heterotrophic biomass (Kd) recorded are 0.394 mgVSS/mgCOD.d and 0.087day-1, respectively. The values of specific substrate removal rate (k), Monodhalf saturation constant (Ks), and maximumspecific growth rate for heterotrophic biomass (µmax) are 0.024 mgCOD/mgVSS.d, 53.203mg/L, and 0.0095day-1, respectively, demonstrating the suitability and healthy performance of MBBR for textile dye wastewater treatment.

Two stage treatability and biokinetic study of dairy wastewater using bacterial consortium and microalgae

Purpose of present research work is to perform nutrient removal and evaluate bio-kinetic coefficients of a two-stage dairy wastewater treatment process in batch reactor using bacterial consortium and microalgae Chlorella pyrenoidosa. The research work was performed in laboratory-scale batch reactor. Primary treated real life dairy wastewater after a treatment with a consortium of bacterial population containing carbon oxidation and nitrification bacteria was taken as the feed material for algal treatment process using microalgae C. pyrenoidosa strain. Nitrate nitrogen which was formed during bacterial nitrification still remaining in bacterial pre-treated dairy wastewater along with phosphorus that have been removed by algal treatment using microalgae of C. pyrenoidosa. The present investigation was done for bacterial and algal treatment of dairy plant effluent in a lab-scale batch reactor with acclimatized seeds of both carbon oxidation, nitrification bacteria, microalgae C. pyrenoidosa and also to evaluate various biokinetic coefficients. Around 95% ammonium nitrogen and soluble chemical oxygen demand (SCOD), around 99.67% and 90.25% of Nitrate nitrogen (NO3−-N) and Phosphorus (PO43-- P) removal were achieved corresponding to initial ammonium nitrogen and SCOD of 55 and 720 mg/L, nitrate nitrogen and phosphorus concentration of 54 and 16 mg/L respectively, with an initial inoculum concentration of bacterial consortium of 15%; corresponding to 1500 mg/L and microalgae C. pyrenoidosa of 0.8% v/v; corresponding to 80 mg/L after 24 h and 8 days of detention period in batch reactor respectively. Kinetic study was also carried out to obtain bio-kinetic coefficient for SCOD, ammonium nitrogen, nitrate nitrogen and phosphorus removal using bacterium and microalgae C. pyrenoidosa.

Kinetic models evaluation for chemical organic matter removal prediction in a full-scale primary facultative pond treating municipal wastewater

Abstract This study focuses on determining the bio-kinetic coefficients of chemical oxygen demand (COD) removal in full-scale primary facultative ponds (PFPs) system on the basis of 3-year continuous operation. The mean removal of chemical oxygen demand (COD), total suspended solid (TSS) and volatile suspended solid (VSS) were 80, 59 and 49%, respectively. The first-order model paired with continuous stirred-tank reactor (CSTR) and plug flow (PF) regimes, PF k–C*, Stover-Kincannon and Grau second-order models were applied to link COD concentrations at the inlet and outlet of the system and to compare the predictive power of models for the estimation of effluent COD concentrations. The Stover-Kincannon model showed the best adaptability (r2 = 0.9294) with the maximum substrate utilization rate (Umax) of 79.14 g/L· d and saturation constant (KB) of 80.65 g/L· d, whereas the Grau second-order model was the best model to predict outlet COD concentrations (r2 = 0.6925). The computed constants, m and n, of the Grau second-order model were 0.6725 and 15.867 d−1, respectively. While the Stover-Kincannon kinetic rates obtained in this study can be used to design the PFP systems in similar operational conditions, the appropriate prediction of pond behavior can be achieved using the Grau model.

Biokinetic Coefficients Determination for the Biological Treatment of Langat River

River basin areas often associated with agriculture, industry and housing are the major source of pollution. This paper was conducted to determine biokinetic coefficients of pilot scale biofilm reactor. The biofilm reactor system (BRS) was installed on Langat River; Malaysia. The system was operated 65 days with different concentrations of mixed liquor suspended solid (MLSS), chemical oxygen demand (COD), and total suspended solids (TSS).Parameters in the influent and effluent of biofilm reactor were determined and biokinetic coefficients of maximum substrate utilization rate (K), half velocity constant (KS), cell yield coefficients (Y), decay coefficient (Kd), and maximum specific growth rate (µmax) were evaluated by Monod equations. Results showed that; the coefficients K, Ks, Y,Kd , and µmax were 1.39 day-1, 53.22 mg/L, 0.302 day-1,0.067 day-1 , and 1.936 day-1. It be can conclude that, all coefficients were in the range of active sludge coefficients that are mentioned in the literature.

Performance and Kinetic Evaluation of Palm Oil Mill Effluent (POME) Digestion in a Continuous High Rate Up-Flow Anaerobic Sludge Blanket (UASB) Bioreactor

In this study, we operated a 10 litre upflow anaerobic sludge blanket (UASB) reactor continuosly at mesophilic temperature (38 °C). UASB reactor performance was evaluated based on the impact of the hydraulic retention time (HRT) ranged between 1 and 5 days and influent COD concentration in the range of 4540 mgL-1 and 20,820 mgL-1. The pH of the UASB was maintained in the range of 6.5 to 7.2 by adding buffering solution containing of 5 gL-1 of calcium oxide (CaO) derived from waste cockle shells. A simplified Monod’s model was employed to describe kinetics of anaerobic digestion of POME by using UASB reactor at organic loading rates (OLR) in the range between 1.17 g.CODL-1d-1 and 17.22 g.CODL-1d-1. A high COD degradation rate of 93.26 % was recorded at OLR of 3.92 g.COD L-1d-1 and HRT of 4 days. The UASB reactor generated the maximum biogas production at 34.95 L/d when operated at HRT 1 day and OLR 7.70 g.CODL-1. The proposed kinetic equations are applicable to describe anaerobic treatment of palm oil mill effluent with the UASB reactor. Biokinetic coefficients evaluated were, the growth yield (YG), 3.906 g VSS/g CODremoved.d-1; the specific biomass decay (b), 0.233 d-1; the specific biomass growth rate (μmax), 1.861 d-1; and the saturation constant (Ks), 3.459 g-CODL-1.

Batch kinetics of nutrients removal for palm oil mill effluent and recovery of lipid by Nannochloropsis sp

Batch experiments were investigated for the effect of initial nutrients concentration of palm oil mill effluent (POME) on nutrients removals, growth rate, and lipid content recovery by Nannochloropsis sp. Bio-kinetic coefficients, k; reaction rate constant, Km, half-saturation constant, and Y, yield coefficient were determined. The concentrations of POME chosen were 0, 20, 40, 60, 80 % diluted with seawater (POME + SW) and Walne’s medium (POME + WM). Nannochloropsis sp. demonstrated the highest specific growth rate (0.39 d−1), maximum cell density (7.93 × 107 cell/mL) and lipid content (61.60 %) in 60 % POME + WM. Chemical oxygen demand (COD) can be removed effectively with k =11.31 mg COD mg−1 DCW d−1, and Km = 3883.04 mgL−1. The highest polyunsaturated fatty acid (PUFA) of microalgae treated in 60 % POME + WM was 59.13 %. For conclusion, 60 % POME + WM medium can be selected for POME remediation for high nutrients removal, growth rate and lipid content recovery.

Meat processing wastewater Phycoremediation by Botryococcus sp.: a biokinetic study and a techno-economic analysis

ABSTRACT The current study was carried out to investigate the biokinetic model of Botryococcus sp. in removing NH4 + and PO4 3- from meat processing wastewater. The removal efficiency of NH4 + ranged from 89.74% to 99.03% and from 92.39% to 99.93% for PO4 3-. The biokinetic coefficients of NH4 + were = 1.72 mg NH4 + mg−1 chl a d−1 and = 52.29 mgL−1. The biokinetic coefficients of PO4 3- were as follows; = 1.13 mg PO4 3- mg−1 chl a d−1 and = 44.45 mg/L. The techno-economic analysis indicated that the fixed capital estimate will cost USD 920,500 with an annual operating 7920 h/year.

Biokinetics of protein degrading Clostridium cadaveris and Clostridium sporogenes in batch and continuous mode of operations.

A quantitative real-time polymerase chain reaction (QPCR) was applied to estimate biokinetic coefficients of Clostridium cadaveris and Clostridium sporogenes, which utilize protein as carbon source. Experimental data of changes in peptone concentration and 16S rRNA gene copy numbers of C. cadaveris and C. sporogenes were fitted to model. The fourth-order Runge-Kutta approximation with non-linear least squared analysis was employed to solve the ordinary differential equations to estimate biokinetic coefficients. The maximum specific growth rate (μmax), half saturation concentration (Ks), growth yield (Y), and decay coefficient (Kd) of C. cadaveris and C.sporogenes were 0.73 ± 0.05 and 1.35 ± 0.32 h-1, 6.07 ± 1.52 and 5.67 ± 1.53 g/L, 2.25 ± 0.75 × 1010 and 7.92 ± 3.71 × 109 copies/g, 0.002 ± 0.003 and 0.002 ± 0.001 h-1, respectively. The theoretical specific growth rate of C. sporogenes always exceeded than that of C. cadaveris at peptone concentration higher than 3.62 g/L. When the influent peptone concentration was 5.0 g/L, the concentration of C.cadaveris gradually decreased to the steady value of 2.9 × 1010 copies/mL at 4 hours HRT, which indicates 67.1% of the initial population reduction, but the wash out occurred at 1.9 and 3.2 hours HRTs. The 16S rRNA gene copy numbers of C. sporogenes gradually decreased to steady values ranging from 1.1 × 1010 to 2.9 × 1010 copies/mL. C. sporogenes species was predicted to wash out at an HRT of 1.6 h.

Foaming control and determination of biokinetic coefficients in membrane bioreactor system under various organic loading rate and sludge retention time

This work aims to control foaming in a submerged membrane bioreactor (SMBR) by optimizing the organic loading rate (OLR) and sludge retention time (SRT) values to decrease the extracellular polymeric substance (EPS) production used for the pharmaceutical wastewater treatment. Four lab-scale SMBRs were operated for a period of more than 8 months to determine the biokinetic coefficients and optimize the SMBR systems operation under the SRT of 5, 10, 15, 20, 25 days and OLRs of 0.03-0.32 gCOD/L.day. The investigation revealed that the lowest foaming quantity was at an organic loading rate of 0.32 gCOD/L.day and a sludge retention time of 15 days related to few protein concentration of EPS. The results also showed that the foaming quality at the OLR of 0.03 gCOD/L.day was higher compared to the greater OLRs in all SRTs. It was found that the yield (Y), the endogenous decay coefficient (kd), the maximum specific growth rate (μmax), and the saturation constant (Ks) of four SMBRs were in the range of 0.073-0.310 mg/mg, 0.985-3.119 day−1, 1.249-3.672 day−1, and 2.63-106.671–232.55 mg/mg, 1–3.156 day mgCOD/L, respectively. Furthermore, the most appropriate operating condition to activated sludge among the SMBRs was the OLR of 0.1 gCOD/L.day and SRT of 15 days. Under these optimum conditions, a 92.8 % COD removal efficiency and 3.708 1/day μmax were achieved.

Removal of heavy metals from mixed domestic and industrial wastewater by activated sludge process using MWCNT

In this study, the effect of multi-walled carbon nanotube (MWCNT) on heavy metal and chemical oxygen demand (COD) removal in the continuous flow activated sludge process was investigated. In order to treat domestic and industrial wastewater together in the biological treatment unit, 50 and 100 mg.L−1 MWCNT were added to laboratory scale reactors, one of which was a control reactor (CR). It was determined that the increase of the MWCNT concentration leads to increase in the rate of removal of COD. COD removal for CR, 50 and 100 mg.L−1 MWCNT was 49.24, 64.95 and 76.46%, respectively. In the first hour Ni (II) removal was achieved in the control reactor (CR) at 65.33%. When 50 and 100 mg.L−1 MWCNT was added to reactors, Ni (II) removal was 71.14% and 79.99%, respectively. Cu (II) and Cr (VI) removal efficiencies were achieved about 99%, during the treatment. It was determined that MWCNT has a positive effect on activated sludge treatment efficiency. As a result, biokinetic coefficients show that reactor volume the size will be smaller and size of sludge handling facility will be the greater with increases in the amount of MWCNT.

Evaluation of recycled paper mill effluent digestion in a modified anaerobic hybrid baffled (MAHB) reactor: reactor performance & kinetic studies

Recycled paper mill effluent (RPME) consists of various organic and inorganic compounds. In this study, modified anaerobic hybrid baffled (MAHB) bioreactor has been successfully used to anaerobically digest RPME. The anaerobic digestion was investigated in relation to methane production rate, lignin removal, and chemical oxygen demand (COD) removal, with respect to organic loading rate (OLR) and hydraulic retention time (HRT). The analysis using kinetic study was carried out under mesophilic conditions (37 ± 2 °C) and influent COD concentrations (1000–4000 mg L−1), to prove its practicability towards RPME treatment. First-order kinetic model was used to clarify the behavior of RPME anaerobic digestion under different OLRs (0.14–4.00 g COD L−1 d−1) and HRT (1–7 d). The result shows that the highest COD removal efficiency and methane production rate were recorded to be 98.07% and 2.2223 L CH4 d−1, respectively. This result was further validated by evaluating the biokinetic coefficients (reaction rate constant (k) and maximum biogas production (ym)), which gave values of k = 0.57 d−1 and ym = 0.331 L d−1. This kinetic data concludes that MAHB presented satisfactory performance towards COD removal with relatively high methane production, which can be further utilized as on-site energy supply.

Batch Kinetics of Nutrients Removal from Synthetic Meat Processing Wastewater by using Microalgae Botryococcus Sp.

Disposed meat processing wastewater contains high range of nutrients such as ammonia nitrogen and orthophosphate which will cause eutrophication and lead to destruction of ecosystem. Therefore, batch experiments were conducted to explore the influence of the range of initial concentration of ammonia nitrogen and orthophosphate found in meat processing wastewater in the removal of those nutrients during phycoremediation of synthetic wastewater by using microalgae Botryococcus sp. Michaelis-Menten rate expression was applied to generate biokinetic coefficients k, reaction rate constant, Km, half saturation constant and Y, yield coefficients. The experiment was conducted using synthetic wastewater with initial NH4-N concentration varying between 30-480 mg/l and PO43- concentrations varying between 14-239 mg/l. The results demonstrate removal efficiency of NH4-N between 42-100 % and PO43- between 63-96 %. Biokinetic coefficients were established as k = 1.72 mg NH4-N /mg chl a/day, Km = 52.29 mg/L and YN = 0.027 mg chl a/mg NH4-N for ammonia nitrogen and k = 1.13 mg PO43-/mg chl a/day, Km = 44.45 mg/L and YP = 0.038 mg chl a/mg PO43- for orthophosphate.

Determination of biokinetic coefficients for nutrient removal from anaerobic liquid digestate by mixed microalgae

Anaerobic digestion is one of the most common methods used to generate energy from renewable sources. However, untreated anaerobic liquid digestate may cause eutrophication if directly discharged into the water bodies due to its high nutrient content. Microalgae can assimilate nutrients especially nitrogen and phosphorous from wastewater for their growth and produce valuable biomass. In this study, batch experiments were carried out to investigate the biokinetic coefficients for nutrient removal of mixed microalgae grown on anaerobic liquid digestate by Michaelis–Menten rate expression. The initial NH3-N concentration was varied between 18.6 and 87.1 mg L−1, while initial PO4-P concentration was between 1.85 and 6.88 mg L−1, which corresponds to 2%, 5%, 7%, and 10% dilution ratio of anaerobic digestate. According to the yield results (mg chl a mg−1 nutrient), mixed microalgae uptake 10 times more nitrogen than phosphorus. Biokinetic coefficients were determined as kN = 2.48 mg NH3-N mg−1 chl a day−1, KmN = 29.3 mg L−1, YN = 0.45 mg chl a mg−1 NH3-N for nitrogen; and kP = 0.21 mg PO4-P mg−1 chl a day−1, KmP = 2.94 mg L−1, YP = 5.03 mg chl a mg−1 PO4-P for phosphorus. The highest chlorophyll production (39 mg L−1 or 3.31 mg L−1 day−1) was observed at the highest dilution ratio of 10%. Moreover, the highest dilution resulted in highest biomass (1.25 g L−1) despite of dark, high ammonicial, and particulate rich wastewater.

ICRP Task Group 95: internal dose coefficients.

Internal doses are calculated using biokinetic and dosimetric models. These models describe the behaviour of the radionuclides after ingestion, inhalation, and absorption to the blood, and the absorption of the energy resulting from their nuclear transformations. The International Commission on Radiological Protection (ICRP) develops such models and applies them to provide dose coefficients and bioassay functions for the calculation of equivalent or effective dose from knowledge of intakes and/or measurements of activity in bioassay samples. Over the past few years, ICRP has devoted a considerable amount of effort to the revision and improvement of models to make them more physiologically realistic representations of uptake and retention in organs and tissues, and of excretion. Provision of new biokinetic models, dose coefficients, monitoring methods, and bioassay data is the responsibility of Committee 2 and its task groups. Three publications in a series of documents replacing the ICRP Publication 30 series and ICRP Publications 54, 68, and 78 have been issued [Occupational Intakes of Radionuclides (OIR) Parts 1-3]. OIR Part 1 describes the assessment of internal occupational exposure to radionuclides, biokinetic and dosimetric models, methods of individual and workplace monitoring, and general aspects of retrospective dose assessment. OIR Parts 2-5 provide data on individual elements and their radioisotopes. Work is also in progress on revision of dose coefficients for radionuclide intakes by members of the public.

Effects of phenol on sulfate reduction by mixed microbial culture: kinetics and bio-kinetics analysis.

Mixed microbial culture collected from the wastewater treatment plant of Indian Institute of Technology Guwahati (IITG) was further grown in anaerobic condition in presence of sulfate where lactate was added as a carbon source. Sulfate addition was increased stepwise up to 1,000 mg l-1 before phenol was added at increasing concentrations from 10 mg l-1 to 300 mg l-1. Kinetics of sulfate, phenol and chemical oxygen demand reduction were studied and experimental findings were analyzed using various bio-models to estimate the bio-kinetic coefficients. This is the first detailed report on kinetics and bio-kinetic studies of sulfate reduction in presence of phenol. Experimental results showed that there was no inhibition of sulfate reduction and microbial growth up to 100 mg l-1 phenol addition. However, inhibition to different degrees was observed at higher phenol addition. The experimental data of microbial growth and substrate consumption in presence of phenol fitted well to the Edward model (R2 = 0.85, root mean square error = 0.001011) with maximum specific growth rate = 0.052 h-1, substrate inhibition constant = 88.05 mg l-1 and half saturation constant = 58.22 mg l-1. The characteristics of the cultured microbes were determined through a series of analysis and microbial tests.