Biochemical Oxygen Demand Load Research Articles

Water quality monitoring and modeling for an urban storm drainage channel in Thane, India.

The absence of a sewer system and inadequate wastewater treatment plants results in a discharge of untreated wastewater to the urban drainage channels and pollutes receiving waters. Field visits were carried out to observe water quality parameters such as dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) in an urban drainage system (Kolshet drain) in Thane City, Mumbai Metropolitan Region, India. Dye-tracing studies using rhodamine WT dye were used for computing the velocity, discharge, and dispersion coefficient of the drain. The data analysis shows that the BOD and COD values in the drain are higher than the permissible limits (30mg L-1 for BOD and 250mg L-1 for COD), which is not suitable for disposal to any receiving water body. Also, the DO was less than the permissible limit of a minimum of 3mg L-1 (for the survival of aquatic life). It is seen that the higher BOD load significantly reduced the DO throughout the drain. The Water Quality Analysis Simulation Program (WASP 8.32, 2019) developed by the US Environmental Protection Agency (USEPA) has been used for the simulation of the DO and BOD in the drainage channel. The model simulates an appropriate estimate of the expected variation of DO and BOD at points of interest. The modeling for the Kolshet drain is expected to enable better estimates of the wastewater parameters and the pollution transport in the drain for planning purposes.

Economics of advanced technologies for wastewater treatment: Evidence from pulp and paper industry

Paper mills generate large quantities of wastewater and sludge waste depending on the type of paper making processes employed. This poses several problems regarding wastewater treatment, discharge, and sludge disposal. Whenever wastewater is generated, it should be treated in wastewater treatment plants prior to being released to the environment since it can be polluting and dangerous. A study was conducted at Star Paper Mills Ltd. Saharanpur, UP to demonstrate the existing and advanced technologies for wastewater treatment. The mill uses woody raw materials such as eucalyptus, poplar, and veener chips to manufacture a wide range of industrial and cultural grade papers, such as absorbent kraft, maplitho, azure lay, and copier. We observed that the most common excess back water is from paper machines, bleach plant effluent, floor cleaning, and other sources of wastewater. High chemical oxygen demand (COD), biochemical oxygen demand (BOD), and low biodegradability are all characteristics of pulp and paper wastewater. Approximately 85–90% of the fresh water utilized is wasted. We examined the wastewater collected and evaluated from the paper mill by Central Pulp and Paper Research Institute (CPPRI). The Effluent treatment plant (ETP) at Star Paper Mills Ltd. is sufficient to facilitate satisfactory removal of suspended matter in clarifiers and oxidation of biodegradable organic matter in aeration tank. As a matter of fact, if the ETP is operated under optimal conditions, the aeration capacity is sufficient to effectively treat even higher BOD loads than the existing load.

Model Matematika Optimasi Multi-Objektif Penurunan Beban Limbah Biochemical Oxygen Demand pada Instalasi Pengolahan Air Limbah

The increase in community activities causes the amount of wastewater to increase. This wastewater comes from industrial production processes and from the community activities which are domestic wastewater. Domestic wastewater must be treated before being discharged to water sources because it contains pathogenic organisms. The place for treating domestic wastewater is Wastewater Treatment Plant (WWTP). The main purpose of WWTP is to degrade the Biochemical Oxygen Demand (BOD) and pathogenic organisms. This study develops a multi-objective optimization mathematical model for reducing the BOD load in the WWTP. This optimization model has three objective functions, namely maximizing the BOD load that is treated in the pond minimizing the difference between the BOD reduction efficiency value in the WWTP with the reference efficiency value and minimizing the power used by the aerator. The simulation results show that the maximum BOD load that can be treated in facultative ponds I and II is 1,589.688 Kg/day while for facultative ponds III and IV is 1,727.158 Kg/day. The efficiency value of reducing BOD load is influenced by the residence time variable, where the efficiency value of reducing the BOD load for facultative ponds I and II by 54% while for facultative ponds III and IV by 57%. The power used by the aerator is influenced by the treated BOD load variable, the aerator power in facultative ponds I and II is 49.67775 Kwh while in facultative ponds III and IV it is 53.97369 Kwh.

Multistage Constructed Wetland in the Treatment of Greywater under Tropical Conditions: Performance, Operation, and Maintenance

Greywater (GW) can be separated in different fractions where the kitchen component might be included. Constructed wetland (CW) systems are commonly used for the onsite treatment of GW, and the fraction treated might impact the performance, operation, and maintenance. These aspects are still poorly explored in the literature and are of importance for a proper design and system sustainability. In this study, a multi-stage household-scale CW system composed of a horizontal flow (HF), followed by a vertical flow (VF) unit, was monitored over 1330 days, focusing on different GW fractions and hydraulic and organic loading rates. The biochemical oxygen demand (BOD) was ~50% lower without the kitchen sink component (GWL) in the system inlet, while no drop was observed in the chemical oxygen demand (COD). Treatment with the GWL component caused a sudden drop in the hydraulic loading rate applied at the HF-CW (~114 to 35 mm per day) and the VF-CW (~230 to 70 mm per day). Even when the HF-CW received ~90 gCOD m−2 per day (GW), the multistage system reached a COD removal of 90%. The lower BOD load when treating GWL avoids clogging and decreases the frequency of maintenance. These variables can be used for the optimal design and operation of a CW, contributing with empirical data to CW guidelines in Brazil, and could additionally be expanded for application in other countries with similar climates.

Environmental reforms in sugar industries of India: An appraisal

Sugar industry in India has imparted significant contribution in the growth of agriculture and socio-economic status of the country. However, continuation of conventional practices owing to lack of awareness for environmentally sustainable technologies has led to the pollution in water resources resulting in degradation of environmental quality. Considering this, Central Pollution Control Board of India took initiative for minimizing the pollution load in rivers by formulating a charter and invoking environmental compensation for sugar industries. Present assessment of environment related reforms through national policy like charter implementation and environmental compensation is one of the primary baseline studies done so far. These reforms were implemented in 85 sugar industries situated along the main stem of River Ganga for validation. The analysis depicted that the implementation of charter and environmental compensation resulted in significant reduction in freshwater consumption (56.4%), effluent generation (13.8%), and biochemical oxygen demand load (34.6%). Thus, similar reforms may be adopted in other sugar industries as well in order to improve the environmental quality and sustained growth of the economy.

Analysis of the Effects of Local Regulations on the Preservation of Water Resources Using the CA-Markov Model

The analysis of the local regulation effects is required for sustainable and effective land utilization because land use/land cover (LULC) changes are not only determined by human activity but are also affected by national policy and regulation; however, previous studies for land use/land cover (LULC) have mainly been conducted on the LULC changes using past experience. This study, therefore, analyzed the effects of local regulations aimed at preserving the water quality in South Korea. To this end, changes in LULC were simulated using the CA-Markov model under conditions in which two local regulations, the special countermeasure area (SCA) and total maximum daily load (TMDL), were not applied and examined the differences between the simulated LULC and the actual LULC as of 2018. In addition, the differences in the generation of pollutant loads were driven for Biochemical Oxygen Demand (BOD), Total Nitrogen (TN), and Total Phosphorus (TP) using pollutant unit-load. As a result, without SCA, the agricultural area increased by 379.0 km2, the urban area decreased by 101.8 km2, and the meadow area decreased by 176.0 km2. In addition, without TMDL, the urban area increased by 169.2 km2 and the meadow area decreased to 158.8 km2.Differences in BOD, TN, and TP pollution loads without SCA applications were shown to decrease to 22,710.5 kg·km−2 day−1, 1133.9 kg·km−2 day−1, and 429.8 kg·km−2 day−1, respectively, while BOD, TN, and TP pollution loads without TMDL applications decreased to 14,435.7 kg·km−2 day−1, 2543.6 kg·km−2 day−1, and 368.2 kg·km−2 day−1, respectively. As such, this study presents a methodology for analyzing the effects of local regulations using the CA-Markov model, which can intuitively and efficiently examine the effects of regulations by predicting LULC changes.

Assessment of lake water quality using multivariate statistical techniques and chlorophyll-nutrient relationships: a case study of the Göksu Lake

This study aimed to evaluate the water quality of the Goksu Lake, which is located in Ankara, Turkey. For this purpose, multivariate statistical analyses, namely, principal component analysis/factor analysis, regression analysis and cluster analysis, and linear regression analysis, were used to determine the relationship between the nutrients. In order to evaluate the status of the lake water quality, the limiting nutrient element was determined using the total nitrogen to total phosphorus ratio (TN/TP). The water quality parameters were selected as pH, turbidity, chemical oxygen demand (COD), suspended solids (SS), dissolved oxygen (DO), biochemical oxygen demand (BOD), total nitrogen (TN), chlorophyll-a (Chl-a), total phosphorus (TP), color, fecal coliform (FC), and total coliform (TC) count. For the cluster analysis, the single-link clustering method using Euclidean distance criteria was preferred. Cluster I consisted of sites 1, 2, 3, and 4, while cluster II consisted of site 5. Two factors were obtained as a result of the factor analysis. These two factors explained 88.2% of the total variance. The first factor clarifies the 45.62% of total variance has pH, COD, DO, TN, TP, color, BOD, and TC strong positive load value. This factor was thought to represent domestic wastewater. The second factor that affects water quality clarifies the 42.54% of total variance has turbidity, SS, Chl-a, and FC strong positive load value. This factor was thought to represent the microbiological activities that occurred as a result of the mixing of wastewaters and also pollution accumulating in the bottom sediment. The nutrient-limiting elements in the water lake quality are determined with TN/TP ratio. Accordingly, the lake water quality was determined as N-limited at two points and co-limited at three points. The relationship between the nutrients was evaluated using regression analysis.

Selection of Optimum Pollution Load Reduction and Water Quality Improvement Approaches Using Scenario Based Water Quality Modeling in Little Akaki River, Ethiopia

The collective impacts of rapid urbanization, poor pollution management practices and insufficient sanitation infrastructure have driven the water quality deterioration in Little Akaki River (LAR), Ethiopia. Water quality modeling using QUAL2Kw was conducted in the LAR aimed at selecting the optimal water quality improvement and pollution load reduction approaches based on the evaluation of five scenarios: modification of point sources (PS) load (S1), modification of nonpoint sources (NPS) load (S2), simultaneous modification of PS and NPS load (S3), application of local oxygenators and fish passages using cascaded rock ramps (S4), and an integrated scenario (S5). Despite the evaluation of S1 resulting in an average load reduction of Biochemical Oxygen Demand (BOD) (17.72%), PO4-P (37.47%), NO3-N (19.63%), the water quality objective (WQO) in LAR could not be attained. Similarly, though significant improvement of pollution load was found by S2 and S3 evaluation, it did not secure the permissible BOD and PO4-P pollution load in the LAR. Besides, as part of an instream measure, a scenario evaluated using the application of rock ramps (S4) resulted in significant reduction of BOD load. All the individual scenarios were not successful and hence an integration of scenarios (S5) was evaluated in LAR that gave a relatively higher pollutant load reduction rate and ultimately was found a better approach to improve pollution loads in the river. In conclusion, pollution load management and control strategy integrally incorporating the use of source-based wastewater treatment, control of diffuse pollution sources through the application of best management practices and the application of instream measures such as the use of cascaded rock ramps could be a feasible approach for better river water quality management, pollution reduction, aquatic life protection and secure sustainable development in the LAR catchment.

Biochemical Oxygen Demand, Nitrogen, Phosphorus and Navigational Carrying Capacities of Bengoh Reservoir for Potential Aquaculture and Recreational Developments

This paper quantifies the biochemical oxygen demand (BOD), nitrogen (N), phosphorus (P) and navigational carrying capacities of Bengoh Reservoir for potential fish cage culture and recreational developments. The pollutant degradation coefficients (k) and pollutant carrying capacities (tons/day) of the reservoir were determined. The computed pollutant degradation coefficients were primarily based on the hydrological information of the catchment, hydraulic and operational details of the dam, and the targeted water quality standards of the river-connected Bengoh Reservoir. The maximum allowable pollutant loading rate (tons/year) defines the reservoir’s maximum Waste Assimilative Capacity (WAC) on specific pollutants (BOD, N and P), while in compliance to the targeted benchmark with the receivable pollutant loadings. It was found that the current BOD, TN and TP loading rates are 0.308 ton/day, 0.119 ton/day and 0.114 ton/day, respectively. To comply with Class I Standards of the National Water Quality Standards of Malaysia (NWQSM), the Maximum Allowable Loading Rates of BOD can be as high as 92.24 tons/day as compared to the current loading rate of 0.308 ton/day, maximum TN loading of 116.63 tons/day versus current 0.119 ton/day, and maximum TP loading at 125.54 tons/day versus current 0.114 ton/day. It was also found that the maximum number 218 cages (225 fish/cage) of Tilapia would be allowed in Bengoh Reservoir so as to comply with Class I of NWQSM. Based on the peak level of the reservoir recreational types of use in demand and the mix of public and private access, the navigational carrying capacity of the reservoir was estimated to be about 130 boats.

Applicability Evaluation of the Hydrological Image and Convolution Neural Network for Prediction of the Biochemical Oxygen Demand and Total Phosphorus Loads in Agricultural Areas

This study employed a convolution neural network (CNN) model, hitherto used only for solving classification problems, with two-dimensional input data to predict the pollution loads and evaluate the CNN model’s applicability. A CNN model generally requires two-dimension input data, such as photographs in previous studies. However, this study’s CNN model necessitates the numerical images that reflect hydrological phenomena due to the nature of the study. A hydrological image was used as the input data for the CNN model in this study to address this issue. The last layer of the CNN model was also transformed into a linear function to derive the continuous variable. As a result, the Pearson correlation coefficient, which represents the relationship between the measured and predicted values, demonstrated a Biochemical Oxygen Demand (BOD) load model of 0.94 and a Total Phosphorus (TP) load model of 0.87. Nash–Sutcliffe efficiency was used to evaluate the model performance; the BOD load model was 0.83, while the TP load model was 0.79, respectively, indicating good performance. These results demonstrate that the hydrological images led to stable model learning and generalization, and the proposed CNN model is suitable for predicting the pollution load, with potential future applications in various fields.

BOD load analysis and management improvement for the Chao Phraya River Basin, Thailand.

The loads of biochemical oxygen demand (BOD) in the Chao Phraya River Basin (CPRB), Thailand were analyzed in terms of how they were generated (BODgen), stocked in the environment (BODen-stock), and discharged into the Chao Phraya River (BODCPR) using material flow analysis. BODgen from the industrial sector was the highest; however, BODen-stock and BODCPR from this point source were not significantly higher than those from the domestic sector. BODgen, BODen-stock, and BODCPR from swine farming and aquaculture across the river basin were lower than those from the domestic and industrial sectors. Of the total 251,884tons per year (t/year) BODCPR, 49,614t/year were in the upper river section, 35,976t/year in the middle river section, and 166,294t/year in the lower river section. These amounts were more than the carrying capacities of the relevant river sections (i.e., 7230t/year, 18,380t/year, and 37,851t/year of the BOD loads for the upper, middle, and lower river sections, respectively). The first priority in BOD reduction in the CPRB should emphasize domestic wastewater by increasing wastewater treatment efficiency and onsite installations of wastewater treatment systems, while the second should be on paddy fields and other nonpoint sources. Specific best management practices may be considered, e.g., creating constructed wetlands or preserving riverbank vegetation as natural swales to alleviate BOD discharge from agricultural activities into water sources.

Full-scale simultaneous partial nitrification, anammox, and denitrification process for treating swine wastewater.

A full-scale swine-wastewater activated sludge treatment plant that contains naturally enriched anammox biofilms was investigated for 2 years. Red biofilm in this system included Planctomycetes at a maximum of 62.5% of the total bacteria diversity, including Candidatus Jettenia and Candidatus Brocadia. The plant was operated with an influent containing 1,104 ± 513 mg/L biochemical oxygen demand (BOD) and 629 ± 198 mg/L total nitrogen (TN) (BOD/N of 1.78 ± 0.58) at a volumetric BOD loading rate of 0.32 ± 0.12 kg/m3/d. Notwithstanding drastically varying influent concentrations, BOD removal efficiency was stable at 95 ± 4%. However, TN removal fluctuated at 75 ± 14%. Dissolved oxygen (DO) concentrations in the aeration tank were 0.06-2.0 mg/L. DO concentration greatly affected nitrogen removal, e.g. when DO was lower than 0.3 mg/L, total inorganic nitrogen removal was 61 ± 14% (≤20 °C), 78 ± 16% (20-30 °C), and 75 ± 12% (≥30 °C), whereas at higher DO concentrations, removal rates were 47 ± 13%, 55 ± 16%, and 68%, respectively. As BOD concentration in the influent was limited compared to nitrogen concentration, nitrogen was likely removed by simultaneous nitrification, anammox, and denitrification (SNAD) under microaerobic conditions. Maintaining low DO concentrations would therefore be a simple method to improve nitrogen removal during SNAD processes for swine-wastewater treatment with fluctuating influent.

Effects of direct discharge of domestic greywater to nearby water body

Domestic greywater is being directly discharged to the ditches without any treatment which affect the environment. Therefore, the investigation was conducted to assess the effects of different sources of greywater to drainage using loading rates while calculate Dissolved Oxygen (DO) level by Streeter-Phelps equation. The contribution of bathroom source from House A was higher with the average of 263.5 L/day followed by kitchen and laundry with the average of 133.04 L/day and 52.14 L/day respectively. Total pollutant produced of greywater from kitchen according to Biochemical Oxygen Demand (BOD) loading rate was high for House A, B and C with the BOD loading rates of 302.1, 194.9 and 274.2 kg/day respectively. Meanwhile, the values of Chemical Oxygen Demand (COD) were the highest by 2019 mg/L from kitchen source of House A and 1962 mg/L from laundry activity of House B. However, the highest value of Total Suspended Solid (TSS) and Turbidity were from kitchen source within 733 mg/L and 104.3 NTU respectively and the highest value of pH was from laundry source within 9.56. From Streeter-Phelps modelling, the value of measured DO at point source has low level of oxygen which was 3.29 mg/L. Therefore, this study was expected to give benefits to local authority as their references or guidelines in greywater planning system.

Обґрунтування доцільності впровадження усереднювачів в технологію очистки господарсько-побутових стічних вод

The inflows of municipal sewages discharged to wastewater treatment plants for full biological treatment can vary widely throughout the day. Therefore, one of the ways of optimizing the operation of wastewater treatment plants is the use of regulating tanks – equalization basins, providing the possibility of uniform supply of wastewater with averaged concentration. The purpose of the paper is to substantiate the feasibility of using equalization basins in the technological cycle of complete biological treatment of household wastewaters. According to the analysis of technological data of the Livoberezhnna Aeration Station (LAS) located in Dnipro City the sewage inflow rates at treatment plant have significant daily variations. In this regard, there is a need to implement a separate technological operation to equalize the water inflow before the primary sedimentation tanks and aeration tanks in order to normalize the flow and average concentration of pollutants. On the basis of the initial data of qualitative and quantitative indicators of water samples chemical analysis the load of biochemical oxygen demand (BOD) at the treatment plant was calculated. The volume of the equalization basin is determined according to the methodology widely used in American universities and engineering companies in the USA. The results of calculations of wastewater averaging according to BOD indicate the effect of equalization of pollutant concentrations during the day. Thus, the ratios of BOD load values for wastewater treatment without equalization and with equalization basins are: maximum to minimum — 25,82 and 2,05; minimum to average — 0,08 and 0,62; maximum to average — 2,06 and 1,27 respectively. It is established that the average wastewater outflow in the volume of 0,307 m3/s allows avoid overloading by BOD concentrations, in contrast to the actual inflow, the volume of which can fluctuate during the day.

A game theoretical low impact development optimization model for urban storm water management

Abstract This study presents a novel framework to optimize Low Impact Development (LID) practices for urban storm water management. First, the Storm Water Management Model (SWMM) model was executed for different possible scenarios of input parameters and various LIDs to simulate runoff volume, Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) loads. Next, a neural network (MLP-ANN) was trained and validated, as a surrogate model, against the set of inputs and output variables from the SWMM model simulations. The inherent uncertainties in the rainfall-runoff modeling were accounted for using a Nonlinear Interval Number Programming (NINP) model, and stakeholders' interactions are considered using a leader-follower game model. Velenjak urban watershed in Tehran, Iran, with four key stakeholders was considered as the study area. Tehran Municipality is the financial service provider that makes the first decision the leader-follower structure, and is considered as the leader with the priority of minimizing LIDs’ construction and maintenance costs. Tehran Department of Environmental Protection, Tehran Regional Water company, and Tehran Province Water and Wastewater company are the main followers in the decision making structure in the study area. This game theoretical framework yields several Pareto optimal solutions given the conflicting utilities of various players, and a Multi Criteria Decision Making procedure – i.e. PROMETHEE model – selects the most preferred compromised option. Fourteen weighting scenarios were considered in the PROMETHEE model to determine the compromise solution among the 52 solutions on the trade-off curve. The novelty of this study lies in using a nonlinear interval conflict resolution multi-objective optimization model for urban storm water management based on a leader-follower game. The proposed methodology warrants BOD and TSS loads, as well as storm water volume, are all reduced, with the highest reductions of 93, 86 and 90 percent, respectively. Results testify to the efficacy of the proposed model for urban storm water management.

Upflow anaerobic sludge blanket reactor and biofilter in polyethylene as an alternative of decentralized wastewater treatment in municipality of Rio Rufino – SC

Basic sanitation services are essential for promoting public health and for mitigating environmental damage. Thus, the objective of this work was to evaluate a wastewater treatment system consisting of anaerobic sludge blanket reactor and biofilter, as an alternative for the decentralized wastewater treatment in the municipality of Rio Rufino - Santa Catarina. The system was evaluated for its efficiency of removal of fecal coliforms, biochemical oxygen demand, chemical oxygen demand, soluble chemical oxygen demand, phosphorus, Total Kjhedal Nitrogen, nitrite, nitrate, sedimentable solids and maintenance of the hydrogen potential in the effluent. The treated effluent had its parameters compared to the standards established by Resolution 430/2011 of the Conselho Nacional do Meio Ambiente and Law 14.675 / 2009 of the State of Santa Catarina. It was also performed the estimate of the daily biochemical oxygen demand load, originated by the population of the municipality, and its respective impact. The effluent treated by the proposed system, when properly installed, follows what was established by the legislation, which implies in reducing the impacts caused by the municipality. In this way, the system can be an interesting alternative when it comes to decentralized wastewater treatment.

Predicting biochemical oxygen demand in European freshwater bodies

Biochemical Oxygen Demand (BOD) is an indicator of organic pollution in freshwater bodies correlated to microbiological contamination. High BOD concentrations reduce oxygen availability, degrade aquatic habitats and biodiversity, and impair water use. High BOD loadings to freshwater systems are mainly coming from anthropogenic sources, comprising domestic and livestock waste, industrial emissions, and combined sewer overflows. We developed a conceptual model (GREEN+BOD) to assess mean annual current organic pollution (BOD fluxes) across Europe. The model was informed with the latest available European datasets of domestic and industrial emissions, population and livestock densities. Model parameters were calibrated using 2008–2012 mean annual BOD concentrations measured in 2157 European monitoring stations, and validated with other 1134 stations. The most sensitive model parameters were abatement of BOD by secondary treatment and the BOD decay exponent of travel time. The mean BOD concentrations measured in monitored stations was 2.10 mg O2/L and predicted concentrations were 2.54 mg O2/L; the 90th percentile of monitored BOD concentration was 3.51 mg O2/L while the predicted one was 4.76 mg O2/L. The model could correctly classify reaches for BOD concentrations classes, from high to poor quality, in 69% of cases. High overestimations (incorrect classification by 2 or more classes) were 2% and large underestimations were 5% of cases. Across Europe about 12% of freshwater network was estimated to be failing good quality due to excessive BOD concentrations (>5 mg O2/L). Dominant sources of BOD to freshwaters and seas were point sources and emissions from intensive livestock systems. Comparison with previous assessments confirms a decline of BOD pollution since the introduction of EU legislation regulating water pollution.

Performance evaluation of a large sewage treatment plant in Brazil, consisting of an upflow anaerobic sludge blanket reactor followed by activated sludge.

The objective of this study was to evaluate the behaviour of a system comprising an upflow anaerobic sludge blanket reactor followed by activated sludge to treat domestic sewage. The Betim Central sewage treatment plant, Brazil, was designed to treat a mean influent flow of 514 L/s. The study consisted of statistical treatment of monitoring data from the treatment plant covering a period of 4 years. This work presents the concentrations and removal efficiencies of the main constituents in each stage of the treatment process, and a mass balance of chemical oxygen demand (COD) and nitrogen. The results highlight the good overall performance of the system, with high mean removal efficiencies: BOD (biochemical oxygen demand) (94%), COD (91%), ammonia (72%) and total suspended solids (92%). As expected, this system was not effective for the removal of nutrients, since it was not designed for this purpose. The removal of Escherichia coli (99.83%) was higher than expected. There was no apparent influence of operational and design parameters on the effluent quality in terms of organic matter removal, with the exceptions of the BOD load upstream of the aeration tank and the sludge age in the unit. Results suggest that this system is well suited for the treatment of domestic sewage.

THE EFFECTS OF SEWAGE EFFLUENT DISCHARGES ON THE WATER QUALITY OF WUPA RIVER IN ABUJA, NIGERIA

The effect of sewage effluents discharge on water quality of the receiving river in the Wupa area of Abuja was studied to determine the assimilative capacity of the receiving river in event of shock load due to treatment plant failure. The river passes through Idu industrial area of Abuja from where effluent from Wupa sewage treatment plant is discharged. Water samples were taken from six stations along the river reach of 16 kilometres within the vicinity of the treatment plant. Both the effluents and the water samples at six selected points along the river were analysed for pH, electrical conductivity (EC), turbidity, biochemical oxygen demand (BOD) and dissolved oxygen (DO). The results were compared with the standards set by National Environmental Standards and Regulations Enforcement Agency (NESREA) for waste water. The result indicates that the BOD load on the river was within the stipulated limit and there exist a moderate degree of self-purification in the river. The study concluded that the river can withstand BOD shock loadings of up to 44.3 mg/L from the treatment plant without injuring the assimilative capacity of the river. Keywords: Water Quality; Biochemical Oxygen Demand; Dissolved Oxygen; Wupa River; Assimilative Capacity

Source Apportionment of Annual Water Pollution Loads in River Basins by Remote-Sensed Land Cover Classification

In this study, in order to determine the efficiency of estimating annual water pollution loads from remote-sensed land cover classification and ground-observed hydrological data, an empirical model was investigated. Remote sensing data imagery from National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer were applied to an 11 year (1994–2004) water quality dataset for 30 different rivers in Japan. Six water quality indicators—total nitrogen (TN), total phosphorus (TP), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and dissolved oxygen (DO)—were examined by using the observed river water quality data and generated land cover map. The TN, TP, BOD, COD, and DO loads were estimated for the 30 river basins using the empirical model. Calibration (1994–1999) and validation (2000–2004) results showed that the proposed simulation technique was useful for predicting water pollution loads in the river basins. We found that vegetation land cover had a larger impact on TP export into all rivers. Urban areas had a very small impact on DO export into rivers, but a relatively large impact on BOD and TN export. The results indicate that the application of land cover data generated from the remote-sensed imagery could give a useful interpretation about the river water quality.