Terms Of Biological Oxygen Demand Research Articles

In-situ magnetic alginate coated chitosan core@shell beads with excellent performance in simulated and real wastewater treatment: Behavior, mechanisms, and new perspectives

Herein, a new hybrid magnetic core@shell biocomposite was prepared based on an alginate-bentonite core and a chitosan shell layer (mAB@Cs) where magnetic Fe3O4 NPs (50.7 nm) were in-situ generated on the surface via a simple non-thermal co-precipitation approach. The biocomposite has a high ability to magnetically separate and remove organic (ciprofloxacin (CPX)) and seven toxic inorganic (Cu2+, Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Hg2+) contaminants from simulated wastewater. Experimental results showed a CPX monolayer chemisorption with a Langmuir maximum adsorption capacity of 264.7 mg/g, maintained effectiveness up to the fifth cycle, and high removal rates of heavy metals ranging from 74.89 % to 99.86 % corresponding to adsorption capacities ranging from 12 to 20 mg/g. For a more accurate evaluation, the biocomposite was tested on a real urban wastewater sample (RWW) and it has manifested a noteworthy efficiency in removing a mixture of inorganic pollutants in terms of potassium K+ and orthophosphate phosphorous P-PO43−, and organic matter in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) with 46 %, 90 %, 84 %, and 64 % removal efficiencies, respectively. On top of this, a high inactivation rate of E. coli of the order of 96 % was recorded, making the prepared magnetic biocomposite adept for the simultaneous removal of emergent wastewater pollutants, from organic, inorganic, to pathogen microorganisms.

Role of constructed wetlands in mitigating the challenges of industrial growth and climate change impacts in the context of developing countries

One of the most persistent issues affecting individuals in developing countries is the lack of access to safe drinking water and sanitary facilities. The adoption of centralized water, energy, and cost-intensive technology has proven ineffective in addressing the complex water-related challenges that have arisen as a consequence of growing urbanization in developing nations. Constructed wetlands have emerged as an effective wastewater treatment solution with natural applications. The fundamental goal of this study is to offer a complete overview of the wide variety of practices, uses, and investigations of constructed wetlands systems for eliminating different pollutants from wastewater in developing countries leading to placing them in the context of climate change, environmental resource planning, and sustainable wastewater treatment systems. CWs offer significant levels of treatment performances with hybrid systems achieving contaminant removal efficiencies up to 93.82% for total suspended solids, 85.65% for chemical oxygen demand, and 80.11% for ammonia nitrogen which is adequate with respect to other viable alternatives. In terms of Biological Oxygen Demand (BOD5), the highest elimination (84.06%) was achieved in hybrid systems when compared to Free water surface CWs (65.34%), Horizontal sub-surface CWs (75.1%), and Floating treatment wetland (55.29%). The maximum power density generation through the microbial fuel cell-based constructed wetlands ranges between 50 and 86 mW/m2in Bangladesh (integrated tidal flow) and 852 mW/m3in China (vertical flow), and the production of bioenergy has been evidenced up to 1,836.5 GJ/hector/year. Annually, wastewater treatment plant systems (WTPs) generate around a hundred times more Methane (CH4), Nitrous oxide (N2O), and carbon dioxide (CO2) than CWs. In metropolitan cities, WTPs may lead to a considerable increase in upstream land use, which could be minimized by promoting CWs in these areas. The potential utility of different CWs in protecting and preserving estuarine quality within the present regulatory framework is finally addressed in the study, emphasizing that it can balance the impacts of industrial expansions in developing countries for subsequent mitigation and adaptation to climate change.

Adsorptive removal of organic pollutants from milk-processing industry effluents through chitosan-titanium dioxide nanoadsorbent-coated sand.

Milk-processing industry effluent (MPIE) poses severe problems for aquatic and environmental systems, especially in the South Asian region. Therefore, its treatment is of great interest. This study deals with the investigation of chitosan titanium dioxide nanoadsorbent (CTiO2) coated onto sand particles via calcination that are used to remove the emerging pollutants. The adsorptive properties of these developed adsorbents are compared with those of the nascent sand without coating as well as with the chitosan titanium dioxide nanoadsorbent coated sand (CTiO2-CS). Batch adsorption experiments were performed to investigate the percent reduction efficiency (%RE) of organic pollutants in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) from synthetic and real effluents. The maximum %RE of BOD (96.76) and COD (98.91) was achieved at 1.5M dose of CTiO2-CS, 120min of contact time, pH 6.5, an initial BOD concentration of 900mg/L, and an agitation speed of 400rpm. Similarly, the %RE of COD was found to be 86.75 for synthetic effluent and 90.97 for real effluent at initial COD concentrations of 8000mg/L. Pseudo-second-order and Langmuir models are found to be the best fits for BOD and COD adsorption. The diffusion model suggests that surface adsorption as well as intraparticle diffusion contribute to the actual adsorption process. Regeneration experiments were performed for four cycles, and CTiO2-CS was found to be the most regenerable adsorbent material. The performance of the adsorbent was compared with previous studies, and it was found to have excellent adsorption capacity. As a result, the developed filter bed could be used as a promising superadsorbent for the removal of organic load in MPIE.

Ecological River Health Assessment Using Multi-Metric Models in an Asian Temperate Region with Land Use/Land Cover as the Primary Factor Regulating Nutrients, Organic Matter, and Fish Composition.

This study was performed to determine the ecological health of a temperate river over nine years (2011–2019); it also analyzed the trophic structure and linkage of nutrients (nitrogen [N] and phosphorus [P]), sestonic chlorophyll-a (CHL-a), and the top trophic fish in the Asian monsoon region. Water chemistry, trophic indicators, and tolerance guilds were primarily influenced by land use and land cover (LULC); the magnitude of variation was also related to geographic elevation, artificial physical barriers (weirs), and point sources. Levels of nutrients, organic matter, and CHL-a largely influenced by the intensity of the monsoon seasonality for a particular LULC and stream order. Mann–Kendall tests based on a long-term annual dataset showed that annual organic matter and CHL-a increased over time because of longer hydraulic residence time after weir construction. The results of empirical nutrient models suggested that P was the key determinant for algal growth (CHL-a); the strong P-limitation was supported by N:P ratios > 17 in ambient waters. Linear regression models and canonical correspondence analysis (CCA) were used to determine the influences of LULC and water quality on the trophic/tolerance linkages, fish community compositions and structures, and river health. Tolerant species had a positive functional relationship with nutrient enrichment through total phosphorus (TP) (R2 = 0.55, p < 0.05) and total nitrogen (TN) (R2 = 0.57, p < 0.05), organic pollution in terms of biological oxygen demand (BOD) (R2 = 0.41, p < 0.05) and chemical oxygen demand (COD) (R2 = 0.49, p < 0.05), and algal growth (R2 = 0.47, p < 0.05); sensitive species exhibited the opposite pattern. The degradation of river health, based on the multi-metric index of biotic integrity (IBI) model, was evident in the downriver region (“fair–poor” condition) and was supported by the quantitative fish community index (QFCI) model. The outcomes suggested that the degradation and variation of ecological river health, trophic linkages of water chemistry (N, P)-algal biomass-fish, were largely controlled by the land use pattern and construction of physical barriers in relation to the Asian monsoon.

ANALISIS BEBAN DAN STATUS PENCEMARAN BOD DAN COD DI KALI ASIN, SEMARANG

Kali Asin is an important river for the drainage system in North Semarang. This river is often drained by domestic and industrial waste. The inclusion of these wastes can cause a decrease water quality marked by an increase Biological Oxygen Demand ( BOD) and Chemical Oxygen Demand (COD) concentrations. The purpose of this study was to determine the load of BOD and COD pollution and assess the status of pollution using the Pollution Index Method based on Government Regulation Number 82 of 2001 class II. Sampling was carried on 17 December 2019-28 January 2020. Sampling was carried out three times, once in 3 weeks. The material used was water samples taken from three stations (estuary, middle of the settlement, and far from the settlement) based on regional characteristics, land use, and sources of pollution. The research method uses a survey method with the technique of determining the location of sampling using purposive sampling. Water quality variables analyzed were temperature, discharge, pH, DO, BOD, COD. Based on the research results, these variables mostly do not meet the quality standards such as BOD and COD variables. The results of the calculation of pollution load in terms of BOD and COD variables obtained an average number of 952.54 kg / day and 3,425.86 kg / day. The results of the pollution index calculation at stations A, B, and C are 3.88; 3.78 and 3.53. The level pollution of Kali Asin was categorized in mild contamination. Keywords: Pollution Load, BOD, COD, Pollution Index, Kali Asin

Method development for evaluating the effectiveness of hydrocarbons on BOD, UBOD and COD removal in oily wastewater.

The effects of different operating parameters on the treatment efficiency of oily wastewater in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) were measured. The analyses of BOD using OxiTop biosensors are reviewed regarding performance characteristics like linearity, response time, precision, agreement between BOD28 values obtained from the biosensors and the ultimate BOD (UBOD), as well as toxic resistance and COD. The wastewater samples were seeded with the bacteria, which were isolated in the current study from Kuwaiti oil-contaminated sand, such as Bacillus mycoidesis and Bacillus subtilis. After 18 days, the margin for saponin solution and oily wastewater using either Rhododcoccus (R), a mixture of Bacillus mycoidesis and Bacillus subtilis (M) or a mixture of R&M exhibited the maximum rate of BOD. It was found that the corresponding COD of the saponin solution (SS) ranged from 1,525 mg/l to 3,890 mg/l by distilled water and the mixture (RM), respectively. The COD of oily wastewater (WW) ranged from 2,900 mg/l to 4,450 mg/l by distilled water and the mixture of (RM), respectively. Moreover, the higher values of BOD28 were recorded when mixtures of bacteria were added together with the saponin solution or oily wastewaters. Furthermore, the average values of UBOD for the oily wastewater with RM or with amendment substance were increased by about 33.5% and 49.5%, respectively. However, BOD 28 /COD ratios for all the selected have been found to be less than 0.4, indicating low aerobic degradability.

Post-treatment of tannery wastewater using pilot scale horizontal subsurface flow constructed wetlands (polishing)

In the present study, a pilot scale horizontal subsurface flow constructed wetland (CW) system planted with Phragmites karka; longitudinal profile was studied. The wetland was fed with tannery wastewater, pretreated in a two-stage anaerobic digester followed by a sequence batch reactor. Samples from each CW were taken and analyzed using standard methods. The removal efficiency of the CW system in terms of biological oxygen demand (BOD), chemical oxygen demand (COD), Cr and total coliforms were 91.3%, 90%, 97.3% and 99%, respectively. The removal efficiency for TN, NO3- and NH4+-N were 77.7%, 66.3% and 67.7%, respectively. Similarly, the removal efficiency of SO42-, S2- and total suspended solids (TSS) were 71.8%, 88.7% and 81.2%, respectively. The concentration of COD, BOD, TN, NO3-N, NH4+-N, SO42 and S2- in the final treated effluent were 113.2 ± 52, 56 ± 18, 49.3 ± 13, 22.75 ± 20, 17.1 ± 6.75, 88 ± 120 and 0.4 ± 0.44 mg/L, respectively. Pollutants removal was decreased in the first 12 m and increased along the CW cells. P. karka development in the first cell of CW was poor, small in size and experiencing chlorosis, but clogging was higher in this area due to high organic matter settling, causing a partial surface flow. The performance of the pilot CW as a tertiary treatment showed that the effluent meets the permissible discharge standards.

Removal of Recalcitrant Carbon from an Industrial Wastewater Using Electrocoagulation

Manufacturing industries synthesize new chemical products every day, which eventually find their way into domestic and industrial wastewaters. As a result, wastewater is becoming increasingly more complex in nature. The emerging pollutants escape the treatment systems and appear in the receiving water bodies. Wastewater treatment plants in India still report effluent parameters in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) at the ppm level, whereas these emerging pollutants, many of whom are non-biodegradable, can be toxic and carcinogenic at the ppb level. Therefore, it is imperative to look for alternatives or upgrade the existing systems which safely remove these harmful compounds from wastewater. In this research, efficiency of electrocoagulation process was assessed in a laboratory-scale setup in removing recalcitrant carbon from a real wastewater. The wastewater was collected from an effluent treatment plant that receives domestic wastewater and industrial effluents from chemical, bulk drugs and allied industries, for treatment. In this study, the wastewater sample was analyzed for total dissolved solids (TDS) and total organic carbon (TOC), and then treated biologically in a respirometer using aerobic microorganisms. After the oxygen uptake curve plateaued, indicating a cessation of biological process, the sample was analyzed for TDS and TOC and put in a lab-scale electrocoagulation setup. Iron and Aluminium electrodes were used in the study and efficiency of the system in removing the recalcitrant/residual carbon and TDS was studied with respect to the reaction time. The results showed that electrocoagulation can be a potential post-biological treatment system for removal of recalcitrant carbon from wastewaters.

Optimized Design of a Hybrid Biological Sewage Treatment System for Domestic Wastewater Supply

This study is aimed at evaluating alternative designs of waste stabilization ponds (WSPs) and constructed wetlands (CWs) for Kaputiei Housing Estate consisting of 2000 low cost housing units in Kenya. The entire analysis was carried out by simulating the effectiveness and purification efficiencies of WSPs and CWs in terms of Biological Oxygen Demand (BOD) reduction and faecal coliform (FC) removal under different scenarios of water treatment systems that included Re-sizing of the initial sewage treatment system, optimizing the design of the initial system and design of hybrid system for the estate. The graphic comparison of the simulated parameters under different scenarios showed that a hybrid design that combines both the WSPs and CWS provides an effluent BOD of 20 mg/l and 195 FC per 100 ml that meets the standard effluent discharge that is acceptable for unrestricted crop irrigation and thus will be reused in the housing estate for kitchen gardening and agroforestry.

Cleaner Production Strategy for Improving Environmental Performance of Small Scale Cracker Industry

Cracker industry is one of thriving small-medium food industries in Yogyakarta Special Province. The cracker processing plant produces wastewater that potentially contaminates the environment. Wastewater coming from the washing of production equipments has the BOD and COD concentration that exceed the treshold of quality standard due to it containing high organic matter. This paper proposes a cleaner production strategy with environmental, economic and technical benefits for small scale cracker industry. Implementation of good housekeeping by improving the worker thoroughness in the production process and cleaning the scrap on the production equipment before washing improves the environmental performance in terms of biological oxygen demand (BOD), chemical oxygen demand (COD) by 76.67% and 84%, respectively.

Drawer compacted sand filter: a new and innovative method for on-site grey water treatment

In this paper, results of a new sand filter design were presented. The drawer compacted sand filter (DCSF) is a modified design for a sand filter in which the sand layer is broken down into several layers, each of which is 10 cm high and placed in a movable drawer separated by a 10 cm space. A lab-scale DCSF was designed and operated for 330 days fed by synthetic grey water. The response of drawer sand filters to variable hydraulic and organic loading rates (HLR and OLR) in terms of biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity and Escherichia coli reductions were evaluated. The HLR was studied by increasing from 72 to 142 L m−2 day−1 and OLR was studied by increasing it from 23 to 30 g BOD5 m−2 day−1 while keeping the HLR constant at 142 L m−2 day−1. Each loading regime was applied for 110 days. Results showed that DCSF was able to remove>90% of organic matter and total suspended solids for all doses. No significant difference was noticed in terms of overall filter efficiency between different loads for all parameters. Significant reduction in BOD5 and COD (P<.05) was noticed after water was drained through the third drawer in all tested loads. The paper concludes that DCSF would be appropriate for use in dense urban areas as its footprint is small and is appropriate for a wide range of users because of its convenience and low maintenance requirements.

Adsorption of pollutants from biodiesel wastewater using chitosan flakes

This work was carried out to evaluate the possibility of using commercial chitosan flakes as an adsorbent for the removal of pollutants from biodiesel wastewater. The effect of varying the adsorption time (0.5–5h), initial wastewater pH (2–8), dosage of adsorbent (1.5–5.5g/L) and mixing rate (120–350rpm) on the adsorption capacity of pollutants, measured in terms of biological oxygen demand (BOD), chemical oxygen demand (COD) and oil & grease levels, was explored by univariate analysis. Under the derived optimal conditions (adsorption time of 3h, initial wastewater pH of 4.0, chitosan at 3.5g/L and agitated at 300rpm), the adsorption capacity of BOD, COD and oil & grease levels were 236, 4503 and 140mg/g, respectively. This corresponds to a reduction in the initial BOD, COD and oil & grease levels of around 76, 90 and 67%, respectively. To facilitate a higher reduction level in the investigated pollutants, the repetitive treatment of the wastewater was performed with satisfactory water quality levels being obtained after four successive treatments. The adsorption kinetics fitted very well with the Langmuir isotherm and the adsorption of all pollutants onto chitosan flake occurs via a physical process. Finally, the reusability of used chitosan by HNO3 or NaOH treatment was explored.

Evaluating the treatment performance of a full scale Activated Sludge Plant in Islamabad, Pakistan

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.

Nutrient removal of effluent from quail farm through cultivation of Wolffia arrhiza

The objective of this work was to study the nutrient removal using the Wolffia arrhiza during the treatment of laying quails farm effluent. The relationship between W. arrhiza biomass and treatment time, the change in water qualities, and nitrogen-balance (N-balance) were evaluated. The results showed that a biomass of 12.0 g of W. arrhiza per liter of effluent and a treatment period of 30 days were found to provide the best conditions for W. arrhiza’s growth and the quality of the treated effluent in terms of biological oxygen demand, suspended solids, total phosphorus, nitrate, total ammonia nitrogen and total Kjeldahl nitrogen. The pH and salinity were similar for each level of biomass. The W. arrhiza biomasses of 4.00–12.0 g/l of effluent were suitable for W. arrhiza survival over time. Since W. arrhiza can fix N in the atmosphere, it can grow very well in effluent containing a low level of N.

Incorporation of aliphatic units into aromatic water-soluble polyesters to improve the performances for warp sizing

Aliphatic units (ethylene succinate) were incorporated into aromatic water-soluble polyesters (WSP) in order to improve their environmental protection and sizing performances. The environmental performance was measured in terms of biological oxygen demand for 5 days (BOD5) and chemical oxygen demand (COD). Apparent and intrinsic viscosities, the adhesion to polyester fibers, glass transition temperature, and mechanical behavior of sizing films of WSP were evaluated for improving their sizing performance. The composition of copolymeric WSP was also investigated by 1H-NMR. A series of copolymeric WSP with a variation in molar ratio of aliphatic monomer (dimethyl succinate) to aromatic monomer (dimethyl terephthalate) from 10:90 to 40:60 was synthesized through a two-step reaction, transesterification and polycondensation. It was found that, by incorporating aliphatic units into the macromolecular chain of aromatic WSP, the environmental performance, apparent and intrinsic viscosities, and the toughness of sizing film were enhanced obviously. The adhesion to polyester fibers showed no sensitivity to the molar ratio of dimethyl succinate to dimethyl terephthalate when the ratio ranged from 10:90 to 30:70. In view of overall performance of the aliphatic-containing WSP sizes, the molar ratio should be 30:70. Based on the ratio, the WSP prepared showed better environmental and sizing performances.

Waste-waste treatment technology and environmental management using sawdust bio-mixture

The industrial wastewater (WW) of potato-chips factory is characterized by its high biological oxygen demand (BOD) and chemical oxygen demand (COD), in addition to a medium content of oil & grease (O&G), total dissolved slats (TDS) and total suspended solids (TSS). A new technique for wastewater treatment has been applied using bio-mixture of selected strains of Aspergillus terreus or Rhizopus sexualis in addition to the natural flora of sawdust (SD-BIOMIX) in the form of mobile micro-carrier in activated sludge system. Different kinds of composted sawdust were used as a microbial carrier, support and source of nutrients and enzymes to enhance the wastewater treatment process; in order to improve the quality of treated wastewater and resulting sludge. The parameters of treated wastewater in terms of BOD, COD, O&G, TDS and TSS were greatly improved by 85.0, 79.0, 82.7, 74.6 and 87.7% respectively, in relation to the retention time and kind of tested materials. The 14 days microbial–treated (composted) sawdust by A. terreus, or R. sexualis as (SD-BIOMIX) exhibited the highest enzymes contents and was the most efficient materials for the wastewater treatment process in comparison with commercial biomixture products e.g. C157 and EM solution. Furthermore, the retention time of the treatment process could be reduced to 4 hr only. Finally, the resulting sludge(s) of (SD-BIOMIX) was easy to separate (in 5–10 min.) from wastewater. The sludge, according the chemical analysis, can be safely used in agriculture as an organic fertilizer and soil conditioner. In addition, different kinds of resulting sludge have been tested as biosorbents and exhibited high ability to remove chromium (89.1 – 99.3%), nickel (84.3 – 98.0%) and zinc (85.6 – 97.7%) from the heavy industrial wastewater. Data indicated the possibility of magnifying the introduced (SD-BIOMIX) as a new technique for the treatment of wastewater and as new trend for wastes management and pollution prevention and could be applied in Kingdom of Saudi Arabia as one of advanced biotechnology to solve many of environmental problems in KSA.

Effect of activated carbon on BOD and COD removal in a dissolved air flotation unit treating refinery wastewater

The effects of powdered activated carbon (PAC) on the performance of a pilot-scale laboratory dissolved air flotation (DAF) unit were investigated. Refinery wastewater of different pollutant concentrations was treated and the effects of different operating parameters on the removal efficiency of pollutants in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) were studied. A circular pilot-scale DAF unit with conical bottom was used and the operating parameters investigated included flow rate, recycle ratio, saturation pressure and the concentration of PAC added. It was found that for dosages of activated carbon in the range of 50–150 mg/l, the removal efficiencies for BOD increased from 27–70% to 76–94% while those for COD increased from 16–64% to 72–92.5% for inlet values of 45–95 mg/l and 110–200 mg/l for BOD and COD respectively. Such findings represent considerable improvement in the performance of the dissolved air flotation unit.

Assessment of the efficiency and economic viability of various methods of treatment of sanitary landfill leachate

This study assesses the efficiency of various physico-chemical, biological and other tertiary methods for treating leachate. An evaluation study on the treatability of the leachate from methane phase bed (MPB) reactor indicated that at an optimum hydraulic retention time of 6 days, the efficiency of the reactor in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) removal was 91.29 and 82.69%, respectively. Recycling of the treated leachate through the municipal solid waste layers in the leachate recycling unit (LRU) resulted in a significant increase in the biodegradation of organics present in the leachate. Optimum BOD and COD removal efficiencies were achieved at the third recycle; additional recycling of the leachate did not produce any significant improvement. Physico-chemical treatment of the leachate demonstrated that alum and lime (Option 2) were more economical than coagulants lime and MgCO(3). A cost analysis of the economics of the various treatments revealed that the alternative treatment consisting of a MPB bed followed by a LRU and aerated lagoon is the most cost-effective treatment. However, the alternative consisting of a MPB followed by the LRU and a soil column, which is slightly more costly, would be the most appropriate treatment when adequate land is readily available.

Use of artificial neural network black-box modeling for the prediction of wastewater treatment plants performance

A reliable model for any wastewater treatment plant is essential in order to provide a tool for predicting its performance and to form a basis for controlling the operation of the process. This would minimize the operation costs and assess the stability of environmental balance. This process is complex and attains a high degree of nonlinearity due to the presence of bio-organic constituents that are difficult to model using mechanistic approaches. Predicting the plant operational parameters using conventional experimental techniques is also a time consuming step and is an obstacle in the way of efficient control of such processes. In this work, an artificial neural network (ANN) black-box modeling approach was used to acquire the knowledge base of a real wastewater plant and then used as a process model. The study signifies that the ANNs are capable of capturing the plant operation characteristics with a good degree of accuracy. A computer model is developed that incorporates the trained ANN plant model. The developed program is implemented and validated using plant-scale data obtained from a local wastewater treatment plant, namely the Doha West wastewater treatment plant (WWTP). It is used as a valuable performance assessment tool for plant operators and decision makers. The ANN model provided accurate predictions of the effluent stream, in terms of biological oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS) when using COD as an input in the crude supply stream. It can be said that the ANN predictions based on three crude supply inputs together, namely BOD, COD and TSS, resulted in better ANN predictions when using only one crude supply input. Graphical user interface representation of the ANN for the Doha West WWTP data is performed and presented.

Solar photocatalytic degradation of humic acids as a model of organic compounds of landfill leachate in pilot-plant experiments: influence of inorganic salts

Humic acids (HA) are known to be present at a high concentration in leachates from “mature” and “old” landfills. In this work, the photocatalytic degradation of Aldrich-Sigma HA as a model of refractory organic of stabilised leachate was studied. The experiments were carried out in HA aqueous suspension of TiO2 (P-25) in CPC reactor at pilot-plant scale in the Plataforma Solar de Almeria (Spain) under solar irradiation and natural pH. The adequate quantity of catalyst for this process was found to be 0.7gl−1. The effect of inorganic ions, commonly present in real leachate such as HCO3−, SO42−, Cl− on photocatalytic degradation of HA was also studied. The ions examined, even in higher concentration for Cl− (4.5g/l) and SO42− (7.75g/l) were found to not affect the photocatalytic process and the similar efficiency of HA removal was ensured. However, the presence of hydrogen carbonate into solution matrix inhibited strongly the photocatalytic reaction. The catalytic oxidation of HA, in particular in the mixture of anions, did not agree with Langumir–Hinshelwood kinetics and the evaluation of results was expressed only as an effect of HA removal versus accumulated energy (QUV, kJl−1) by photoreactor. Moreover, the effect inorganic matrix on initial adsorption of HA has been discussed on the basis of the results obtained in laboratory batch test. Additionally, the biodegradability evolution during photodegradation of HA was evaluated in terms of biological oxygen demand (BOD5) as well as by oxygen uptake rate.