Biochemical Oxygen Demand Analysis Research Articles

Impact of Air-Cathodes on Operational Stability of Single-Chamber Microbial Fuel Cell Biosensors for Wastewater Monitoring

The increasing global water pollution leads to the need for urgent development of rapid and accurate water quality monitoring methods. Microbial fuel cells (MFCs) have emerged as real-time biosensors for biochemical oxygen demand (BOD), but they grapple with several challenges, including issues related to reproducibility, operational stability, and cost-effectiveness. These challenges are substantially shaped by the selection of an appropriate air-breathing cathode. Previous studies indicated a critical influence of the cathode on both the enduring electrochemical performance of MFCs and the taxonomic diversity at the electroactive anode. However, the effect of different gas diffusion electrodes (GDE) on 3D-printed single-chamber MFCs for BOD biosensing application and its effect on the bioelectroactive anode was not investigated before. Our study focuses on comparing GDE cathode materials to enhance MFC performance for precise and rapid BOD analysis in wastewater. We examined for over 120 days two Pt-coated air-breathing cathodes with distinct carbonaceous gas diffusion layers (GDLs) and catalyst layers (CLs): cost-effective carbon paper (CP) with hand-coated CL and more expensive woven carbon cloth (CC) with CL pre-applied by the supplier. The results show significant differences in electrochemical characteristics and anodic biofilm composition between MFCs with CP and CC GDE cathodes. CP-MFCs exhibited lower sensitivity (16.6 C L mg−1 m−2) and a narrower dynamic range (25 to 600 mg L−1), attributed to biofouling-related degradation of the GDE. In contrast, CC-MFCs demonstrated superior performance with higher sensitivity (37.6 C L mg−1 m−2) and a broader dynamic range (25 to 800 mg L−1). In conclusion, our study underscores the pivotal role of cathode selection in 3D-printed MFC biosensors, influencing anodic biofilm enrichment time and overall BOD assessment performance. We recommend the use of cost-effective CP GDL with hand-coated CL for short-term MFC biosensor applications, while advocating for CC GDL supplied with CL as the preferred choice for long-term sensing implementations with enduring reliability.

A "2-in-1" Bioanalytical System Based on Nanocomposite Conductive Polymers for Early Detection of Surface Water Pollution.

This work proposes an approach to the formation of receptor elements for the rapid diagnosis of the state of surface waters according to two indicators: the biochemical oxygen demand (BOD) index and toxicity. Associations among microorganisms based on the bacteria P. yeei and yeast S. cerevisiae, as well as associations of the yeasts O. polymorpha and B. adeninivorans, were formed to evaluate these indicators, respectively. The use of nanocomposite electrically conductive materials based on carbon nanotubes, biocompatible natural polymers-chitosan and bovine serum albumin cross-linked with ferrocenecarboxaldehyde, neutral red, safranin, and phenosafranin-has made it possible to expand the analytical capabilities of receptor systems. Redox polymers were studied by IR spectroscopy and Raman spectroscopy, the contents of electroactive components were determined by atomic absorption spectroscopy, and electrochemical properties were studied by electrochemical impedance and cyclic voltammetry methods. Based on the proposed kinetic approach to modeling individual stages of bioelectrochemical processes, the chitosan-neutral red/CNT composite was chosen to immobilize the yeast association between O. polymorpha (ks = 370 ± 20 L/g × s) and B. adeninivorans (320 ± 30 L/g × s), and a bovine serum albumin (BSA)-neutral composite was chosen to immobilize the association between the yeast S. cerevisiae (ks = 130 ± 10 L/g × s) and the bacteria P. yeei red/CNT (170 ± 30 L/g × s). After optimizing the composition of the receptor systems, it was shown that the use of nanocomposite materials together with associations among microorganisms makes it possible to determine BOD with high sensitivity (with a lower limit of 0.6 mg/dm3) and detect the presence of a wide range of toxicants of both organic and inorganic origin. Both receptor elements were tested on water samples, showing a high correlation between the results of biosensor analysis of BOD and toxicity and the results of standard analytical methods. The results obtained show broad prospects for creating sensitive and portable bioelectrochemical sensors for the early warning of environmentally hazardous situations based on associations among microorganisms and nanocomposite materials.

Chemical oxygen demand and biochemical oxygen demand analysis of discharge waters from laundry industry: monitoring, temporal variability, and biodegradability

In Europe, chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) are used as organic indicators for the analytical characterization of laundry water. However, the values of these indicators are derived from one-off analytical measurements at a defined frequency. In addition, there are few data on the temporal variability of COD and BOD5 parameters and on water biodegradability beyond 5 days. In this work, samples of physicochemical treated wastewater were collected for 1 year and their content in COD and BOD5 measured, with BOD monitored over 35 days. The results showed that, for the 24 samples studied, the average and standard deviation values were 835 ± 176 mg/L for COD and 445 ± 114 mg/L for BOD5, indicating a biodegradability index of 2.0 ± 0.4. The interpretation of the data also indicated that the concentrations were close to emission limit value, particularly for BOD5. BOD21 values were particularly high compared to the initial COD, indicating the biodegradability of water. Laundry effluents were also rich in substances very quickly biodegradable, which has been demonstrated by the values of the ratio between BOD7 and BOD5. However, a significant proportion of surfactants is not degraded, as shown by measurements of total organic carbon and anionic surfactant analysis. The results of this study could help the industrial partner involved in our project to guide its choice of the complementary method to better treat wastewater and to reduce its organic load.

CONTRIBUTORY IMPACT OF SEWAGE ON POLLUTED OGUN AND LAGOS FISHING WATERS: INFLUENCE ON ANTIOXIDANT PROFILE AND PROXIMATE COMPOSITION OF SILVER CATFISH (Chrysichthys nigrodigitatus)

Water pollution, a recurring phenomenon in fishing waters of industrial cities in Nigeria, inadvertently constitute hazards to the host biotic communities and the ecosystem. To continuously delineate the impacts of pollution via sewage outlets on aquatic life, this rainy season study investigated Chrysichthys nigrodigitatus, an aquatic food from Ogun River and Epe Lagoon, Nigeria, both of which are locally channeled for sewage release. Sixty (60) samples of C. nigrodigitatus were collected from six sites each representing a group (n=10), with mean weight and length of 762.20 ± 11.05 g and 42.21 ± 0.30 cm respectively. Ajegunle (control), Alaapa and Quarry (test sites) along the Ogun River course in Abeokuta; Ebute-Alashe (control), Oluwo and Marina (test sites) along the Epe Lagoon. Analysis of Biochemical Oxygen Demand and Chemical Oxygen Demand showed elevated variations at the sampled test sites than the control sites and above WHO safe limits. Significant (p < 0.05) increases in concentrations of heavy metals (lead, arsenic and cadmium) in the fishing waters from the sampled test locations particularly the Quarry and Marina sites, as well as in blood samples of fish, were observed when compared with their respective controls. Antioxidants profiling showed significant increases (p < 0.05) in superoxide dismutase and catalase activities in fishes from Alaapa (14- and 3- folds), Quarry (8- and 4- folds), Oluwo (9- and 3- folds) and Marina (8- and 3- folds) sites, while significant increases in glutathione-S-transferase activity were observed only in fishes from Quarry (5- fold) and Marina (4- fold) sites respectively. The glutathione concentration significantly decreased in fishes from all the test sites while malondialdehyde concentrations significantly increased in fishes from all the test sites compared with the respective controls. Proximate analysis of the fish samples showed significant increases (p < 0.05) in moisture and fiber contents, but significant decrease in fat, ash and protein contents compared with the respective controls. The results of the study showed that sewage pollution of fishing waters is hazardous to aquatic life as it induces oxidative stress and significantly reduces the nutritional value of the fishes obtained from such water bodies.

Comparative Analysis of Groundwater Quality near a Dumping Ground in Garchuk Area, Guwahati

Abstract: This project focuses on analyzing and comparing the water quality of a dumping ground, nearby residential area, and commercial area in Garchuk, Guwahati. Water samples were collected from these three locations using tube wells and various parameters were assessed to evaluate the water quality. The analysis included the measurement of Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD). The Winkler method was employed for DO analysis, involving the oxidation of divalent manganese hydroxide precipitate by dissolved oxygen in the water sample. The BOD determination assessed the oxygen required for the biochemical degradation of organic material during a specified incubation period. Results from the DO analysis indicated varying levels of dissolved oxygen in the water samples collected from the dumping ground, residential site, and commercial site. BOD analysis revealed the oxygen utilization and degradation of organic material in the water samples after a 5-day incubation period. Additionally, the concentrations of heavy metals such as lead (Pb), arsenic (Ar), zinc (Zn), copper (Cu), and mercury (Hg) were analyzed in the groundwater samples. The results showed that some heavy metal concentrations were below the detectable limit, while others exhibited measurable levels. The findings of this study provide valuable insights into the water quality of the studied areas, indicating potential pollution levels and the effectiveness of waste treatment processes. These results contribute to better understanding and management of water resources in the Garchuk area, helping to protect the environment and public health.

In situ and self-adaptive BOD bioreaction sensing system based on environmentally domesticated microbial populations

Biochemical oxygen demand (BOD) is a water quality parameter of vital importance. Rapid BOD analysis methods have emerged to simplify the five-day BOD (BOD5) measurement protocol. However, their universal implementations are restricted by the tricky environmental matrix (including environmental microbes, contaminants, ionic compositions, etc.). Here, an in situ and self-adaptive BOD bioreaction sensing system consisting of a “gut-like” microfluidic coil bioreactor with self-renewed biofilm was proposed for the establishment of a rapid, resilient and reliable BOD determination method. With the spontaneous surface adhesion of environmental microbial populations, the biofilm was colonized in situ on the inner surface of the microfluidic coil bioreactor. Exploiting the environmental domestication during every real sample measurement, the biofilm was capable of self-renewal to adapt to the environmental changes and exhibited representative biodegradation behaviors. The aggregated abundant, adequate and adapted microbial populations in the BOD bioreactor rendered a total organic carbon (TOC) removal rate of 67.7% within a short hydraulic retention time of 99 s. As validated by an online BOD prototype, exceptional analytical performance was achieved in terms of reproducibility (relative standard deviation of 3.7%), survivability (inhibition by pH and metal ion interference of <20%) and accuracy (relative error of −5.9% to 9.7%). This work rediscovered the interactive effects of the environmental matrix on BOD assays and demonstrated an instructive attempt by making use of the environment to develop practical online BOD monitoring devices for water quality assessments.

Analysis of Biochemical Oxygen Demand (BOD) and Fecal Coliform Bacteria In Ngringo River Water, Karanganyar Regency

Ngringo River is one of the major rivers in Karanganyar Regency. There are various activities along the river, including domestic and industrial activities where waste discharges enter the river body, causing a decrease in water quality. One of the microorganisms contained in domestic waste that acts as an indicator of pollution in the Ngringo River is Fecal Coliform bacteria, so it is necessary to calculate the total Coliform to determine the presence of pollution in the Ngringo River. The purpose of this study was to determine the total abundance of Coliforms, BOD (biological Oxygen Demand) levels and water quality status based on PP RI No. 22 of 2021. Sampling method used in this study was a random sampling. Sampling consisted of 2 place, namely upstream and downstream. The results showed that the BOD (biological Oxygen Demand) value in the upstream part of the Ngringo river was 1.08 mg/l and 3.40 mg/l downstream, while the Fecal Coliform value in the upstream part of the Ngringo river was 16000 MPN/100ml. and in the downstream part of 5400 MPN/100ml. Based on research results that BOD still meets the quality standard according to PP RI Number 22 of 2021 while the Fecal Coliform value does not meet the quality standard according to PP RI Number 22 of 2021 which means there is pollution in the river Ngringo.AbstrakSungai Ngringo merupakan salah satu sungai besar di Kabupaten Karanganyar. Terdapat berbagai aktivitas di sepanjang aliran sungai tersebut, diantaranya aktivitas domestik dan industri dimana buangan limbah masuk ke dalam badan sungai sehingga menyebabkan penurunan kualitas perairan. Salah satu mikroorganisme yang terkandung dalam limbah domestik yang berperan sebagai indikator pencemaran di Sungai Ngringo yaitu bakteri Fecal Coliform sehingga perlu dilakukan perhitungan total Coliform guna mengetahui adanya pencemaran di Sungai Ngringo. Tujuan dari penelitian ini adalah untuk mengetehui total kelimpahan Coliform, kadar BOD (Biological Oxygen Demand) dan status mutu air berdasarkan PP RI No 22 Tahun 2021. Metode sampling yang digunakan dalam penelitian ini yaitu metode random sampling. Pengambilan sampel terdiri dari 2 tempat yaitu hulu dan hilir. Hasil penelitian menunjukan Nilai BOD (Biological Oxygen Demand) pada bagian hulu air sungai Ngringo sebesar 1,08 mg/l dan pada bagian hilir sebesar 3,40 mg/l, sedangkan Nilai Fecal Coliform pada bagian hulu air sungai Ngringo sebesar 16000 MPN/100ml dan pada bagian hilir sebesar 5400 MPN/100ml. Berdasarkan hasil penelitian bahwa BOD masih memenuhi baku mutu menurut PP RI Nomor 22 tahun 2021 sedangkan nilai Fecal Coliform tersebut tidak memenuhi baku mutu menurut PP RI Nomor 22 tahun 2021 yang berarti terjadi pencemaran di Sungai Ngringo.

Microbial Biosensors for Rapid Determination of Biochemical Oxygen Demand: Approaches, Tendencies and Development Prospects.

One of the main indices of the quality of water is the biochemical oxygen demand (BOD). A little over 40 years have passed since the practical application of the first microbial sensor for the determination of BOD, presented by the Japanese professor Isao Karube. This time span has brought new knowledge to and practical developments in the use of a wide range of microbial cells based on BOD biosensors. At present, this field of biotechnology is becoming an independent discipline. The traditional BOD analysis (BOD5) has not changed over many years; it takes no less than 5 days to carry out. Microbial biosensors can be used as an alternative technique for assessing the BOD attract attention because they can reduce hundredfold the time required to measure it. The review examines the experience of the creation and practical application of BOD biosensors accumulated by the international community. Special attention is paid to the use of multiple cell immobilization methods, signal registration techniques, mediators and cell consortia contained in the bioreceptor. We consider the use of nanomaterials in the modification of analytical devices developed for BOD evaluation and discuss the prospects of developing new practically important biosensor models.

Prediction of Biochemical Methane Potential of Palm Oil Mill Effluent

Exploring green energy options constitute a contemporary tenet in designing a sustainable future. This study investigated the independent variables (milling scales, types of fresh fruit bunches and seasons) that define the dynamics of biochemical methane potential (BMP) or bio-methane and organic content in palm oil mill effluent (POME) generated in ADAPALM (large-scale mill) and palm oil mills in its surrounding communities, located in Ohaji/Egbema LGA, Imo State, Nigeria. The eight communities that constitute ADAPALM were categorised into three strata in relation to the number of small-scale mills in each community (1-5mills, 6-10mills, 11-15mills). Besides the lone large and medium-scale mills, a small-scale mill was randomly sampled from a community in each stratum. Four homogenous samples of POME were collected from each mill for laboratory analysis of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC) and total carbon (TC) using standard methods for wastewater analysis. Prediction of BMP for each sample of POME composition and fraction of substrate used for cell synthesis (fs) wherein POME is classified was computed using biogas package. Data was analysed using tools of SPSS. Multiple linear regression reveals that there is a significant relationship between the predicted volume of BMP with milling scales and seasons (p&lt;0.01), R2=0.927. Similarly, multivariate analysis of variance (MANOVA) shows that the organic content of POME is significantly related to milling scales and seasons (p&lt;0.01). At fs=8% in methanogenic condition, BMP is 22.800±0.282LCH4/m3POME and 75.532±0.149LCH4/m3POME in the wet and dry seasons respectively. These respectively correspond to methane production capacity of 0.057±0.005KgCH4/KgCOD and 0.014±0.001KgCH4/KgCOD. The variance explained by the dependent variable (R2) indicates the importance of these independent variables in determining the BMP and organic content of POME in the area. The predicted dynamics of BMP and their associated wastewater composition provide useful tools in regulating the wastewater content and evaluating its feasibility for bio-energy development.

Numerical simulations of stochastic biochemical oxygen demand equations via RBF method

ABSTRACT This paper proposes a new approach to numerical simulations of stochastic biochemical oxygen demand equations. The analysis of biochemical oxygen demand is necessary in evaluating the effects of water pollution. Here, we consider radial basis functions. This approximation process can also be interpreted as a simple kind of neural network. An illustrative example is included to demonstrate the validity and applicability of the approach. The numerical experiments show that the method performs well.

Environmental effects of concretes produced from partial replacement of cement and sand with coal ash

Environmental effects of concretes produced from partial replacement of cement and sand with coal ash were investigated. Oxide composition of coal ash and cement was determined with X-ray fluorescence spectrometer, while particle size and shape were determined using scanning electron microscope. Concrete mixtures were produced by replacing cement and sand with coal ash at 10, 20, 30 and 40%. Their workability, setting times and compressive strengths were obtained using iron cube mold, Vicat apparatus and compression testing machine, respectively. Biochemical oxygen demand (BOD) and pH of curing water were analyzed. Pollution potential of the cement and concretes produced by partially replacing cement with coal ash was evaluated using CO2 emission simulation. Concretes in which sand was replaced with coal ash (CAS) had better slumps and compressive strengths than those in which cement was replaced with coal ash (CAC). Setting times increased as more coal ash was added but were lower for CAS. BOD analysis of curing water showed it was safe for livestock consumption and body contact during recreational use. CO2 emissions and concrete carbonation analysis showed blending of cement with coal ash reduced emissions which ranged from 0.22 to 0.33 kg but was 0.37 kg in conventional concrete. CAC-40:60 had the lowest emission of CO2 from cement. CO2 uptake after 50-year service life showed that CAC-30:70 had the highest absorption-to-emission ratio of 38.5%. Secondary application of coal ash in concrete production should be encouraged as concretes of similar strengths were obtained with reduction in environmental pollution.

Biofuel Cell Based on Bacteria of the Genus Gluconobacter as a Sensor for Express Analysis of Biochemical Oxygen Demand

The anode of a microbial fuel cell was used to determine the index of biochemical oxygen demand. The fuel cell was developed with an activated graphite electrode modified with polyvinyl alcohol containing N-vinylpyrrolidone. The combination of polyvinyl alcohol with N-vinylpyrrolidone was used to immobilize Gluconobacter oxydans bacteria. The application of this matrix made it possible to obtain a microbial fuel cell possessing a high sensitivity and a minimal time for a single measurement of the BOD5 index, which were 8.3 mV dm3/mg O2 and 30 min, respectively. The lower limit of the determined values of biochemical oxygen demand was 0.34 mg O2/dm3. The determination of the wastewater BOD5 indicated that these results agreed with the data of the standard method (the correlation coefficient was 0.99). The studied biosensor model exceeded the described analogs in such characteristics as the lower limit of detection and the minimal time for a single measurement.

Characterization and analysis of petrochemical wastewater through particle size distribution, biodegradability, and chemical composition

Abstract The centralized treatment method is a widely used form of wastewater treatment that tends to be less effective at removing toxic substances. Therefore, a detailed analysis of the composition of wastewater can provide important information for the design of an effective wastewater treatment process. The objective of this paper was to investigate particle size distribution (PSD), biodegradability, and the chemical composition of the petrochemical wastewater discharges. For this purpose, this project selected the petrochemical wastewater and treated wastewater of China National Offshore Oil Corporation Zhongjie Petrochemical Co, Ltd. as the analysis objects. The step-by-step filtration method, along with a molecular weight classification method, was selected to build the chemical oxygen demand (COD) and biochemical oxygen demand (BOD) fingerprints of petrochemical wastewater and treated wastewater. The results showed that the main pollutants were settleable particles in petrochemical wastewater, which contributed to over 54.85% of the total COD. The colloidal particles with particle sizes in the range of 450–1000 nm had the highest COD value in the treated wastewater, which contributed 34.17% of the total COD of treated wastewater. The results of the BOD analysis showed that the soluble fractions were the main reason that treated wastewaters did not meet the treatment standards. Tests on the organic compounds in petrochemical wastewater found that there were mainly linear paraffins, branched paraffins, benzene series compounds, and some plasticizers in the influent of the petrochemical wastewater. The most abundant pollutants in treated petrochemical wastewater were the adjacent diisobutyl phthalate and the linear alkanes. Fourier transform infrared (FTIR) transmission spectroscopy analysis showed that the settleable particles of petrochemical wastewater and membrane bioreactor (MBR)-treated wastewater contained multiple types of organic substances. The results also indicated that removing the oil-settleable substances, the colloidal particles (450–1000 nm), and the soluble organics will be necessary for the treatment of petrochemical wastewater.

Current Energy Position of New York State Wastewater Treatment Facilities

In 2008, the New York State Energy Research and Development Authority (NYSERDA) published the Statewide Assessment of Energy Use by the Municipal Water and Wastewater Sector documenting 2003/2004 energy use at New York State wastewater facilities. Since the publication of these data, interest in energy efficiency and energy generation has grown considerably. Survey data indicated that a third of the respondents had completed capital projects to reduce energy use, and 65% indicated that they have future energy projects planned. At the same time, regulatory and technology changes such as tighter nutrient limits have added to many plants' electrical demands. This research assesses the magnitude of energy performance shifts over the past 10 years based on the net effect of efficiency gains, increased electrical production, and increased process equipment loads. In facilities larger than 75 mgd, an overall trend toward increased average electrical energy consumption was observed, with recent implementation of nutrient removal being the most significant factor in this trend. Small- and medium-sized facilities (less than 75 mgd) appear to be slightly improving their energy performance based on analysis of biochemical oxygen demand (BOD)-normalized energy metrics (kilowatt-hours per pound of BOD). Water resource recovery facilities (WRRFs) with more developed energy approaches were more likely to have completed capital projects, operational optimization, and building-related improvements to reduce energy use. This title belongs to WERF Research Report Series ISBN: 9781780407784 (eBook)

PERBANDINGAN RASIO BOD/COD PADA AREA TAMBAK DI HULU DAN HILIR TERHADAP BIODEGRADABILITAS BAHAN ORGANIK

Pond is one place that is used as a place to cultivate fish, shrimp, and other aquatic animals that can live in brackish water. Changes in water quality upstream and downstream of the pond due to pollutants may affect the ecological balance of waters. Pollutants can be determined by two simple parameters, the biochemical oxygen demand (BOD) and chemical oxygen demand (COD). While the ability to break down pollutants (biodegradability) can be determined using the ratio of BOD/COD. BOD analysis using the Winkler titration method, whereas the COD analysis using titrimetric method. The value of BOD, COD, and the ratio of BOD/COD in the upstream area is 28.00 mg/L, 60.00 mg/L, and 0,467 respectively. While the value of BOD, COD, and the ratio of BOD/COD in the downstream area is 20.00 mg/L, 43.00 mg/L, and 0.465 respectively. Ratio BOD/COD obtained show that the organic pollutants in the pond is biodegradable.

Efficient mathematical model to verify the leaching process effect in a watercourse

This paper presents the viability to use a mathematical model to ascertain the pollutant carriage in a watercourse, under the leaching process effect or not. An impoundment system was divided in 15 compartments homeomorphic to rectangles, and the simulations considered results in analysis of biochemical oxygen demand, and natural decay rate variations, among other variables. A system of difference equations was used for modelling. It is reliable to use this model to predict pollutant concentration in water, and to simulate the runoff effects with different decay rates.

Rapid field estimation of biochemical oxygen demand in a subtropical eutrophic urban lake with chlorophyll a fluorescence.

Development of a technique for rapid field estimation of biochemical oxygen demand (BOD) is necessary for cost-effective monitoring and management of urban lakes. While several studies reported the usefulness of laboratory tryptophan-like fluorescence technique in predicting 5-day BOD (BOD₅) of wastewater and leachates, little is known about the predictability of field chlorophyll fluorescence measurements for BOD of urban lake waters that are constantly exposed to the mixture of chemical compounds. This study was conducted to develop a numeric relationship between chlorophyll a fluorescence and BOD for a eutrophic urban lake that is widely representative of lake water conditions in the subtropical southern USA. From October 2012 to September 2013, in situ measurements at the studied lake were made every 2 weeks on chlorophyll a fluorescence and other water quality parameters including water temperature, pH, dissolved oxygen, and specific conductivity. Water samples were taken for 5-day BOD and 10-day BOD (BOD₁₀) analysis with and without incubation. The results showed a clear seasonal trend of both BOD measurements being high during the summer and low during the winter. There was a linear, positive relationship between chlorophyll a fluorescence and BOD, and the relationship appeared to be stronger with the 10-day BOD (r(2) = 0.83) than with the 5-day BOD (r(2) = 0.76). BOD dropped each day with declining chlorophyll a fluorescence, suggesting that die-off of phytoplankton has been the main consumption of oxygen in the studied lake. Ambient conditions such as rainfall and water temperature may have partially affected BOD variation.

Wavelet and statistical analysis of river water quality parameters

Statistical and wavelet analysis of water quality parameters COD (chemical oxygen demand), BOD (biochemical oxygen demand), DO (dissolved oxygen), WT (water temperature), AMM (free ammonia), TKN (total kjeldahl nitrogen), TC (total coliform), FC (fecal coliform) and pH (potential of hydrogen) monitored at Nizamuddin bridge-mid stream (Delhi) of Yamuna River in India have been studied. It has been observed that COD is highly correlated with BOD, AMM and TKN. Daubechies wavelet at level 5 (Db5) have been calculated for each water quality parameters as it gives the finer scale approximation and decomposition of each water parameters. Wavelet decomposition and approximation using Db5 of each parameters presented in seven parts namely s, a5, d1, d2, d3, d4 and d5 where “s” represents signal or raw data; low frequency part “a5” gives an approximate of signal at level 5; high frequency parts d1, d2, d3, d4 and d5 contains the detail of “s” at different levels respectively.

A sensitive ferricyanide-mediated biochemical oxygen demand assay for analysis of wastewater treatment plant influents and treated effluents

Representative and fast monitoring of wastewater influent and effluent biochemical oxygen demand (BOD) is an elusive goal for the wastewater industry and regulatory bodies alike. The present study describes a suitable assay, which incorporates activated sludge as the biocatalyst and ferricyanide as the terminal electron acceptor for respiration. A number of different sludges and sludge treatments were investigated, primarily to improve the sensitivity of the assay. A limit of detection (LOD) (2.1 mg BOD5 L−1) very similar to that of the standard 5-day BOD5 method was achieved in 4 h using raw influent sludge that had been cultured overnight as the biocatalyst. Reducing the microbial concentration was the most effective means to improve sensitivity and reduce the contribution of the sludge's endogenous respiration to total ferricyanide-mediated (FM) respiration. A strong and highly significant relationship was found (n = 33; R = 0.96; p < 0.001; slope = 0.94) between BOD5 and FM-BOD equivalent values for a diverse range of samples including wastewater treatment plant (WWTP) influent and treated effluent, as well as several grey water samples. The activated sludge FM-BOD assay presented here is an exceptional surrogate method to the standard BOD5 assay, providing representative, same-day BOD analysis of WWTP samples with a comparable detection limit, a 4-fold greater analytical range and much faster analysis time. The industry appeal of such an assay is tremendous given that ∼90% of all BOD5 analysis is dedicated to measurement of WWTP samples, for which this assay is specifically designed.

Biofilm reactor based real-time analysis of biochemical oxygendemand

We reported a biofilm reactor (BFR) based analytical system for real-time biochemical oxygen demand (BOD) monitoring. It does not need a blank solution and other chemical reagents to operate. The initial dissolved oxygen (DO) in sample solution was measured as blank, while DO in the BFR effluent was measured as response. The DO difference obtained before and after the sample solution flowed through the BFR was regarded as an indicator of real-time BOD. The analytical performance of this reagent-free BFR system was equal to the previous BFR system operated using phosphate buffer saline (PBS) and high purity deionized water in reproducibility, accuracy and long-term stability. Besides, this method embraces many notable advantages, such as no secondary pollution. Additionally, the sample solutions are free from temperature controlling and air-saturation before injection. Significantly, this is a real-time BOD analysis method. This method was successfully carried out in a simulated emergency, and the obtained results agreed well with conventional BOD5. These advantages, coupled with simplicity in device, convenience in operation and minimal maintenance, make such a reagent-free BFR analytical system promising for practical BOD real-time warning.