Characterization of non point source pollutants and their dispersion in Lake Victoria: A case study of Gaba landing site in Uganda

The aim of this research is to characterize non point pollutants and their dispersion in Lake Victoria. Lake Victoria is one of the largest freshwater bodies in the world. The lake is bordered by Kenya, Tanzania, and Uganda, and has streams and rivers stretching as far as Burundi and Rwanda feeding into it. A number of studies have reported deteriorating water quality due to pollution. In this study, non point source pollution was the focus and such as 68 and 64 samples were collected over two rain seasons and dry season, respectively. All samples were analyzed for nutrients, namely, ammonia, nitrite, nitrate, and phosphate. Portable meters were used to measure pH, electrical conductivity (EC) total dissolved solids, temperature and dissolved oxygen instantaneously at point of sample collection while Wagtech methods was used to measure nutrients. Total suspended solids (TSS) were measured using gravimetric method. Within the lake, samples were taken at for horizontal transects of 10 m interval over a distance of 50 m from the shore where surface runoff was released. At each 10 m sampling point, three samples were drawn at vertical distances of 0.5, 1.0 and 1.5 m from water surface using a hand pump with graduated delivery pipe. The criterion to be maximized is the R-squared (R²) value, which is expressed in percent. The values obtained from R² in this study reflect the percentage of output (that is, concentrations of ammonia, phosphorus, nitrates and nitrites) variation explained by the model. Optimization of R² value is important to avoid model over fitting during model identification. Over fitted models produce poor fits during model validation. The results generally show runoff during wet season increases the concentrations of ammonia, phosphorus, nitrites and nitrates. Ammonia varied from 0.1 to 0.19 mg/L, phosphorus from 0.01 to 0.18 mg/L, nitrites from 0.01 to 0.05 mg/L and nitrates 0.02 to 0.36 mg/L. Field measurements confirmed that nutrient concentrations decrease as one move deeper from the shores into the lake due to dilution.Key words: Control applications in environmental processes, batch process modeling and control, water quality, nutrients, Lake Victoria

A review of modeling approaches in activated sludge systems

The feasibility of using models to understand processes, predict and/or simulate, control, monitor and optimize WasteWater Treatment Plants (WWTPs) has been explored by a number of researchers. Mathematical modeling provides a powerful tool for design, operational assistance, forecast future behavior and control. A good model not only elucidates a better understanding of the complicated biological and chemical fundamentals but is also essential for process design, process start-up, dynamics predictions, process control and process optimization. This paper reviews developments and the application of different modeling approaches to wastewater treatment plants, especially activated sludge systems and processes therein in the last decade. In addition, we present an opinion on the wider wastewater treatment related research issues that need to be addressed through modeling.Key words: Mathematical modeling, water, wastewater, wastewater treatment plants, activated sludge systems

Determining and modeling the dispersion of non point source pollutants in Lake Victoria: A case study of Gaba Landing site in Uganda

Lake Victoria is an important source of livelihood that is threatened by rising pollution. In this study, pollutants in runoff are characterized and their dispersion after they enter the lake is measured and modeled at different points in the study areas. The objective is to develop a one dimensional mathematical model which can be used to predict the nutrient (ammonia, nitrite, nitrate, and phosphate) dispersion distances within the lake. A comparison between rain period nutrient concentrations and dry period nutrient concentrations within the Lake showed an elevation in nutrient levels during the rainy season, with exception of nitrate. However, nitrate had high levels during the dry season. Ammonia was found to disperse to horizontal distances of 38 m; nitrite 45 m, with nitrate and phosphate each attaining distances of 34 m. Measured nutrient concentration within the Lake compared well with model estimations.Key words: Modeling, water quality, nutrients, lake Victoria

Estimation of methane generation based on anaerobic digestion and mass balance at Kiteezi Landfill, Kampala, Uganda

Kiteezi landfill site is the main solid waste dumping site in Kampala City (Uganda). In this study, the generation of methane from waste at Kiteezi landfill was measured using laboratory-scale anaerobic digestion experiment and estimated using the Mass balance model. The samples were collected in the wet and dry seasons, with five replicates for each season which were processed for further experiments focused on moisture content analysis and anaerobic digestion. The moisture content analysis results showed a significant change (P < 0.05) between wet season and dry season. Also, the anaerobic digestion revealed that moisture content was a determining factor in gas generation. The average monthly methane production estimate from the mass balance model was 1.63 Gg methane/month and was comparable (within 14%) to the amount estimated by laboratory-scale anaerobic digestion experiment (1.43 Gg methane/month). It is a worthwhile undertaking to further investigate the potential of commercially producing methane from Kiteezi landfill as an alternative source of green and clean energy for urban masses.Keywords: Solid waste management, methane generation, anaerobic digestion and mass balance model

Effect of polyaluminium chloride water treatment sludge on effluent quality of domestic wastewater treatment

Water resources degeneration is accelerated by the discharge of untreated wastewater and its byproducts, hence, reuse of these wastes is a major contributor to sustaining fresh water for the coming decades. In this study, the reuse of polyaluminium water treatment sludge (PA-WTS) as a flocculant aid to improve the effluent quality of wastewater during primary sedimentation is evaluated and presented. PA-WTS was collected from Gabba water treatment plant (Gabba WTP) Uganda, after the coagulation-flocculation process that makes use of aluminium chlorohydrate (ACH). The average aluminium residue concentration in PA-WTS was 3.4 mg/L. During this study, batch laboratory experiments were conducted in a jar-test apparatus in which different doses of PA-WTS were added. The results obtained showed a decrease in total suspended solids (TSS), chemical oxygen demand (COD), total ammonium nitrogen (TAN), and total phosphates (TP) in the supernatant after 30 min of settlement. The optimal PA-WTS dosage of 37.5 mL/L significantly (P<0.05) increased the TSS, TP and COD removal efficiencies by 15, 22 and 30%, respectively. It can be concluded that the PA-WTS positively complimented the sedimentation process in the primary treatment of wastewater to achieve better effluent quality.Key words: Aluminium chlorohydrate, poly aluminium sludge, reuse, wastewater, water treatment sludge

FluNet: An AI-Enabled Influenza-like Warning System

Influenza is an acute viral respiratory disease that is currently causing severe financial and resource strains worldwide. With the COVID-19 pandemic exceeding 153 million cases worldwide, there is a need for a low-cost and contactless surveillance system to detect symptomatic individuals. The objective of this study was to develop FluNet, a novel, proof-of-concept, low-cost and contactless device for the detection of high-risk individuals. The system conducts face detection in the LWIR with a precision rating of 0.98, a recall of 0.91, an F-score of 0.96, and a mean intersection over union of 0.74 while sequentially taking the temperature trend of faces with a thermal accuracy of ± 1 K. While in parallel determining if someone is coughing by using a custom lightweight deep convolutional neural network with a precision rating of 0.95, a recall of 0.92, an F score of 0.94 and an AUC of 0.98. We concluded this study by testing the accuracy of the direction of arrival estimation for the cough detection revealing an error of ± 4.78°. If a subject is symptomatic, a photo is taken with a specified region of interest using a visible light camera. Two datasets have been constructed, one for face detection in the LWIR consisting of 250 images of 20 participants’ faces at various rotations and coverings, including face masks. The other for the real-time detection of coughs comprised of 40,482 cough / not cough sounds. These findings could be helpful for future low-cost edge computing applications for influenza-like monitoring

Quantitative image analysis for the characterization of microbial aggregates in biological wastewater treatment : a review

Quantitative image analysis techniques have gained an undeniable role in several fields of research during the last decade. In the field of biological wastewater treatment (WWT) processes, several computer applications have been developed for monitoring microbial entities, either as individual cells or in different types of aggregates. New descriptors have been defined that are more reliable, objective, and useful than the subjective and time-consuming parameters classically used to monitor biological WWT processes. Examples of this application include the objective prediction of filamentous bulking, known to be one of the most problematic phenomena occurring in activated sludge technology. It also demonstrated its usefulness in classifying protozoa and metazoa populations. In high-rate anaerobic processes, based on granular sludge, aggregation times and fragmentation phenomena could be detected during critical events, e.g., toxic and organic overloads. Currently, the major efforts and needs are in the development of quantitative image analysis techniques focusing on its application coupled with stained samples, either by classical or fluorescent-based techniques. The use of quantitative morphological parameters in process control and online applications is also being investigated. This work reviews the major advances of quantitative image analysis applied to biological WWT processes.The authors acknowledge the financial support to the project PTDC/EBB-EBI/103147/2008 and the grant SFRH/BPD/48962/2008 provided by Fundacao para a Ciencia e Tecnologia (Portugal)

Lead uptake of water plants in water stream at Kiteezi landfill site, Kampala (Uganda)

The purpose of this study was twofold: (i) to quantify the lead (Pb) uptake by two water plants reeds (Phragmites australis) and papyrus (Cyperus papyrus) in water stream at Kiteezi landfill site, Kampala (Uganda) and (ii) to compare the two species in Pb uptake downstream. As such, leachate samples were collected at the inlet and outlet of the waste water treatment plant (WWTP) at Kiteezi landfill site. A total of 6 plant samples of both plant species, P. australis and C. papyrus, were picked from three different sites at intervals of 10, 20 and 30 m taken from the exit point of the WWTP, as the reference point. All samples were taken to the laboratory for analysis in a cool container. The concentration of Pb in the samples was measured using the atomic absorption spectrometer (AAS), Perkin Elmer Model. The obtained data was analyzed using descriptive statistics and two-way Anova. The results showed that there was no significant difference (P > 0.05) in the mean Pb content up taken by both plants (reeds and papyrus). Significant quantities of Pb were present in the plants in the range of 1.68 to 5.46 mg/100 g. The removal efficiency of the plants was found to be 12.4 times higher than WWTP. The highest concentrations of Pb were found downstream at a distance of 30 m away from the reference point. Although, the plants were generalized as having equal uptake levels, the two species had different mechanisms with reeds being accumulators and papyrus being excluders. Therefore, reeds are preferable phytoremediators since when harvested by cutting as practiced by some communities in Uganda, the Pb can easily be removed from the environment.Key words: Lead-uptake, excluders, accumulators, phytoremediation, leachates and Kiteezi

A two-stage decentralised system combining high rate activated sludge (HRAS) with alternating charcoal filters (ACF) for treating small community sewage to reusable standards for agriculture

Water scarcity increasingly drives wastewater recovery. Campaigns towards re-use of wastewater are not very common in Africa among other factors, due to a lack of efficient and cost-effective technology to treat wastewater to re-usable standards. In this study, two treatment systems, a high rate activated sludge (HRAS) system and alternating charcoal filters (ACF) are combined and used to treat wastewater to standards fit for reuse in agriculture. The charcoal can upon saturation be dried and used as fuel. Two different ACF lines were used in parallel after the HRAS: ACF1 with a residence time of 2.5 h and ACF2 with residence time of 5 h. Results show no significant difference (α = 0.05) in the performance of the two filter lines, hence ACF1 with a higher flow rate was considered as optimal. The HRAS effectively removed up to 65% of total suspended solids (TSS) and 59% of chemical oxygen demand (COD), while ACF1 removed up to 70% TSS and 58% COD. The combined treatment system of HRAS and ACF1 effectively decreased TSS and COD on average by 89 and 83%, respectively. Total ammonium nitrogen (TAN) and total phosphates (TP) were largely retained in the effluent with average removal percentages of 19.5 and 27.5%, respectively, encouraging reuse for plant growth.Key words: A-stage, sustainable wastewater treatment, resource recovery, developing countries, water reuse, nutrient management, agriculture