Search

A packed-bed anaerobic-aerobic reactor (PBAOR) with two anaerobic and two aerobic compartments was constructed to treat manure-free piggery wastewater which was characterized by high ammonium (NH4+-N) and low ratio of chemical oxygen demand (COD) to total nitrogen (TN). Performed for 60 days at the normal atmospheric temperature of 25℃ with a constant hydraulic retention time of 32 h and reflux ratio of 2.0, a stable state in pollutants removal was obtained in the PBAOR. Within the next routine operation process, the removal of COD, NH4+-N and TN was above 85.7%, 98.2% and 85.8%, with a residual less than 81.7, 7.2 and 39.9 mg L-1 in effluent, respectively. Twelve veterinary antibiotics classified into tetracyclines (TCs), sulfonamides (SAs) and fluoroquinolones (FQs) were detected from the piggery wastewater. and the PBAOR was effective in removing TCs and SAs with an average removal of 74.8% and 93.3%, respectively, but presented a negative removal for FQs. Most COD in the piggery wastewater was mainly removed in the first two anaerobic compartments along with an obvious removal of TCs and SAs, while the TN were mainly removed in the last two aerobic compartments with the negative removal of FQs.

In order to monitor the ecological status of the largest Egyptian northern drains, an environmental comparison is performed between Bahr El Baqar Drain and Hadous Drain based on water quality and the community composition of their phytoplankton groups to assess the environmental hazard impacts on Lake Manzala. From both drains during the period 2015–2020 (5 years average), fourteen parameters were seasonally recorded; Hydrogen Ion, biological oxygen demand, chemical oxygen demand, electric conductivity, total suspended solids, total dissolved solids, bicarbonates, cations and anions (nitrates, sulfates, Calcium, Sodium, Potassium, Magnesium and Chloride), as well as seven heavy metal parameters (Copper, Iron, Manganese, Nickel, Lead, Boron, and Zinc). Statistically, phytoplankton seasonal dominance and abundance, diversity indices, species richness, evenness, Shannon and Simpson indices, and Pearson correlation were statistically calculated. The results showed that the average values of pH, HCO3, BOD, COD, EC, TSS, TDS, NO3, anions and cations in Bahr El Baqar Drain were higher than those in Hadous Drain. Phytoplankton groups in both drains belonged to five major groups with a descending order of dominance; Cyanophyta > Chlorophyta > Bacillariophyta > Euglenophyta > Dinophyta. Bicarbonates positively correlated with Chlorophyceae (evenness = 0.871, Shannon = 2.029), Cyanophyceae (1.964, 0.853), Euglenophycea (0.857, 1.535), and Dinophyceae (0.836, 0.918). BOD and COD positively correlated with Nitzschia sp., Euglena velata, and Peridinium volzii, and negatively correlated with Amphora sp., Euglena viridis, and Ceratium hirundinella. Chlorophyceae correlated positively with K, Mg, Cl, SO4 and NO3. Cyanophyceae correlated negatively with K, Mg, Na, B, Cl and SO4. Bacillariophycea positively correlated with Ni and NO3. Dinophyceae negatively correlated with Cl and SO4. Phytoplankton species expressed different dominance, diversity indices and statistical correlation with each water quality parameter, which reflected the selectivity and growth manners of algae. From the former mentioned results, it was concluded that the phytoplankton groups are very sensitive and useful indicator of the health status of any water stream. Concerning the bad quality of water in Bahr El Baqar Drain and Hadous Drain, management plan should be implemented for both drains, in particularly Bahr El Baqar Drain, to preserve the environmental status of Lake Manzala.

Manganese ion (Mn2+) generated from metallurgical, steel making and chemical industries enters sewage treatment plants and affects the sludge activity and flocculation. The effect of Mn2+ on the removal of chemical oxygen demand (COD) and total phosphorus (TP) and sludge activity were investigated in anoxic zone of an anaerobic/anoxic/oxic (A2O) process. The compositions and structures of extracellular polymeric substances (EPS) were characterized using three-dimensional excitation emission matrix fluorescence spectroscopy (3D-EEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) to reveal the relationship among Mn2+, EPS and sludge flocculation. The results showed that low concentration of Mn2+ ( 10 mg/L) hindered microbial flocculation and reduced removal efficiencies of the pollutants. When Mn2+was 5 mg/L, removal efficiencies of COD and TP reached 65% and 90%, respectively. Sludge flocculation was the best and SVI was 70.56 mL/g. The changes of Mn2+ concentration caused deviation of groups’ compositions in LB-EPS and TB-EPS, where the main components were always protein (PN) and polysaccharide (PS). The addition of Mn2+ resulted in the degradation of humic acids. However, it did not give rise to significant morphology changes of EPS.

The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen (TN) removal efficiency was reduced from 85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter of granular sludge was 0.13 mm higher than that without BC. The settling velocity was increased by elevated COD concentration, while the EPS and VSS/SS were increased with BC addition. The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition, and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia. The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD, while the abundance of anammox related functional genes of decreased. The functional genes related to anammox was hydrazine synthase encoding genes (hzsA, hzsB and hzsB). The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L. The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase. It is interesting to note that BC addition greatly enriched the related functional genes of denitrification and anammox.

Micron-grade high iron-containing fly ash (MHIFA)—a processed hazardous waste containing Fe3O4—was added to an up-flow anaerobic sludge blanket reactor to improve the removal performance of high concentration phenol-containing wastewater. The chemical oxygen demand and total phenol removal efficiency with MHIFA were 72.13% and 81.83%, respectively. Moreover, MHIFA addition increased the contents of coenzyme F420 and extracellular polymeric substances, as well as higher electron transport system activity in activated sludge. Additionally, microbial community analysis revealed that the total methanogens contents increased at genera level, producing an increase in methane production, while enriched Geobacter along with archaea Methanothrix might collaborate in direct interspecies electron transfer (DIET) by MHIFA stimulation, promoting the effect of phenolic compound fermentation. Finally, this technology allows for resource utilization of hazardous waste and enhances anaerobic degradation of toxic and refractory pollutants.

Urban black blooms that are primarily caused by organic carbon are deleterious environmental problems. However, detailed studies on the microbial characteristics that form urban black blooms are lacking. In this study, we observed the composition, diversity, and function of bacterial community in the overlying water and sediments during the occurrence and remediation of urban black blooms using high-throughput 16S rRNA gene amplicon sequencing analysis. First, we found that pivotal consortia in the overlying water increased significantly during the formation of black blooms, including the genera Acidovorax, Brevundimonas, Pusillimonas, and Burkholderiales involved in the degradation of refractory organics, as well as the genera Desulfovibrio, Dechloromonas, and Rhizobium related to the production of black and odorous substances. An RDA analysis revealed that chemical oxygen demand, dissolved oxygen, and oxidation reduction potential were related to the changes in microbial community composition. Furthermore, aeration was found to accelerate the removal of ammonia nitrogen and enhance the function of microbial community by stimulating the growth of order Planktomycetes during the remediation of black blooms, but aeration substantially damaged the microbial diversity and richness. Therefore, the health of the aquatic ecosystem should be comprehensively considered when aeration is applied to restore polluted waterbodies. Notably, we observed a large number of pathogenic bacteria in urban black blooms, which emphasizes the importance of treating domestic sewage so that it is harmless. Together, these findings provide new insights and a basis to prevent and manage urban black blooms.

This study aimed to investigate the treatment of paint production industry (PPI) wastewater, which is characterized by low biodegradability and high concentrations of resistant organic matter, by persulfate enhanced electrocoagulation process (EC-PS). A regression quadratic model was developed to describe the removal of chemical oxygen demand (COD) and color number (CN) from PPI wastewater. The effects of independent variables (initial pH, PS dose, current density, and reaction time) on system responses and the interaction between the parameters were determined. Validation experiments were carried out under the optimum conditions determined by the quadratic model (initial pH: 5, PS dose: 5.6 g/L, current density: 21 mA/cm2, and reaction time: 35 min) and 64% COD and 98.1% CN removal were obtained. Pollutant removal efficiencies increased with the increase of PS dose, current density, and reaction time while the highest removal efficiencies were achieved at acidic pH values. The scavenging studies indicated that although the sulfate radicals were the dominant radical type, both hydroxyl and sulfate radicals were involved in the process. In the synergistic effect studies performed under optimum conditions, the highest reaction rate was obtained in the EC-PS process with a value of 0.074 1/min. Specific energy consumption under optimum conditions was calculated as 20.4 kWh/kg COD. The results of the study showed that the EC-PS is an effective process for the treatment of PPI wastewater and response surface methodology is an applicable technique for the optimization of the variables.

Adhesive wastewater from adhesive-producing industries is a kind of refractory organic wastewater containing high chemical oxygen demand (COD) and ammonia nitrogen. In this study, the electrocoagulation and electrochemical technology were in series attempted to treat adhesive wastewater from adhesive-producing industries. The effects of operating parameters such as current density and initial pH were investigated to determine the optimum electrocoagulation parameters. The removals of COD and ammonia nitrogen achieved 81.62%, and 50.92%, respectively, under the optimum electrocoagulation conditions (current density of 5 mA/cm2, pH 3, 2 g/L Na2SO4 supporting electrolyte solution, 60 min of electrocoagulation). The effluent of electrocoagulation was subsequently treated by electrochemical oxidation. The effects of operating parameters, such as current density, initial pH, and supporting electrolyte, on the degradation of COD and ammonia nitrogen were investigated. The COD and ammonia nitrogen removal ratios were both as high as nearly 100% after electrolysis of 120 min (current density of 35 mA/cm2, pH 8.4, 2 g/L NaCl supporting electrolyte solution). The results of excitation-emission-matrix (EEM) revealed the changes of different dissolved organic matter after electrocoagulation and electrochemical oxidation treatment. The experimental results proved that the electrocoagulation combined with electrochemical oxidation methods are the potential technologies for treatment of adhesive wastewater.

A treatment process based on microfiltration followed by nanofiltration (MF-NF) is proposed for textile wastewater treatment. The NF concentrate is further treated by UV/H2O2, Fenton, and photo-Fenton processes. Results showed that the dye was efficiently retained by the MF membrane (>99.1%), which allowed its reuse. The MF-NF was able to reject 92% of the chemical oxygen demand (COD) and >98.5% of colour. When the NF concentrate was treated by UV/H2O2, it was achieved a maximum COD removal of 63% in the condition C:H2O2 1:3 (molar ratio of COD and hydrogen peroxide) and pH 3. The Fenton process, optimized through response surface methodology, achieved 84.7% of COD removal, which increased when combined with UV irradiation (92.2%). An analysis of the NF permeate physicochemical quality and its treated concentrate suggested that it can be reused in the textile industry for different purposes as yarn washing-off and equipment’s washdown. The operating cost for MF-NF corresponded to 0.240 US$/m3 and, including the cost of NF concentrate treatment by photo-Fenton, 0.517 US$/m3, lower than currently practiced by the water distribution company. The system proposed for water reuse and NF concentrate treatment was able to increase the water recovery and decrease the environmental impacts that could be caused by the NF concentrate disposal.

Murray-Darling Freshwater Research CentreMDFRC item.Sediment oxygen demands and water-atmosphere methane emissions of a highly productive, freshwater wetland on the floodplain of the River Murray in south-eastern Australia were quantified over a 14 month period in 1993–1994. Total sediment oxygen demands ranged from 1.3 to 3.3 mmol m−2 h−1, of which < 3 to 90% was due to chemical oxygen demand. Methane emissions ranged from < 0.01 mmol m−2 h−1 in winter to 2.75 mmol m−2 h−1 in summer. Methanogenesis accounted for at least 60% of the combined aerobic and methanogenic carbon flux in sediments from Eleocharis sphacelata beds, and at least 30% and 40% of the combined flux in sediments from Myriophyllum sp. beds and Vallisneria gigantea beds, respectively. In vitro incubations, using additions of sulfate and of molybdate, failed to indicate unequivocally competition for substrates between sulfate-reducing and methanogenic bacteria. However, in vitro methanogenesis was strongly inhibited by nitrate, suggesting an interaction between benthic methanogens and denitrifying or other nitrate-reducing bacteria. Fe3+ decreased in vitro methanogenesis by 16–49% during January, February and March 1994; oxidation of organic matter at the expense of the reduction of ferric ions could be a significant route for detritus processing in Eleocharis-bed sediments in the warmer months. Methanogenesis was increased consistently by additions of some low molecular weight substrates, such as acetate, but not by others, such as methanol, propionate and trimethylamine. Complex polymeric substrates, such as cellulose, starch and aquatic plant matter, increased in vitro methanogenesis rapidly and markedly. Despite this, no relationship between methane emissions and benthic cellulase activity was observed in the field. Methanogenesis was strongly temperature dependent, being maximal at 30 to 40°C and minimal at 5°C, thereby explaining the strong seasonality observed in methane emissions in situ.

Hydrolysis is widely used in sludge treatment as it enables to improve the biodegradability of sludge. However, there was little information about the hydrolysis efficiency with the mixture of primary and secondary sludge. In this study, the hydrolysis and reduction of mixed sludge after thermophilic bacteria (TB) pretreatment was investigated. Volume ratio of 1:3 (primary sludge: secondary sludge) had best release rate of organics, and the soluble chemical oxygen demand (SCOD), carbohydrate and protein in extracellular polymeric substances (EPS) decreased by 7.9, 4.1, 7.2 times, respectively. Meanwhile, the accumulation of SCOD, carbohydrate and protein in dissolved organic matter (DOM) was enhanced with mixed sludge. Excitation-emission matrix (EEM) spectroscopy proved that mixture of sludge was beneficial for the releasing of biodegradable substances. The sludge reduction of mixed sludge was higher than that of single sludge, and mixed sludge (1:3) had the best suspended solid (SS) and volatile suspended solids (VSS) reduction rate of 27.2% and 34.3%.

Modified maifanite (MMF) was prepared by the synthesized method with sulfuric acid treatment and high-temperature calcination and evaluated as an effective adsorption material to remove the nutrient salt in waste watery. Compared with the raw maifanite (RMF), the MMF exhibited a higher adsorption capacity and higher removal efficiency. The results showed that the adsorption rates of total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH3-N), nitrate-nitrogen (NOx-N), and chemical oxygen demand (COD) by MMF were 86.7%, 44.9%, 29.1%, 19.8%, and 11.9%, respectively, and compared to RMF, the average adsorption capacity of these nutrients by MMF increased by 20.5 mg/kg, 126.2 mg/kg, 61.9 mg/kg, 117.18 mg/kg, and 86.9 mg/kg, respectively. MMF maintained the basic structure and composition of maifanite, while having a rougher and looser surface, more irregular pores, wider gaps, and more active materials such as oxidizing Fe. This study suggests that MMF can be further applied to treat domestic sewage and eutrophic water.

In exploring the application of natural coagulants in industrial wastewater treatment, plant-based coagulants have been gaining more interests due to their potential such as biodegradability and easy availability. Hylocereus undatus foliage as a plant-based coagulant has been proven to be efficient during the coagulation-flocculation process; however, limited research has been reported focusing only on palm oil mill effluent (POME) and latex concentrate wastewater. In addition, no previous study has been carried out to determine the performance evaluation of Hylocereus undatus foliage in treating different types of wastewater incorporating different operating conditions using optimization techniques. Hence, this study employed response surface methodology (RSM) in an attempt to determine the performance evaluation of the coagulant in paint wastewater treatment. Four independent factors such as the pH value, coagulant dosage, rapid mixing speed and temperature were chosen as the operating conditions. Three water parameters such as turbidity, chemical oxygen demand (COD) and suspended solids (SS) were chosen as responses in this study. Results revealed that through central composite design (CCD) via Design Expert software, the optimum conditions were achieved at pH 5, coagulant dosage of 300 mg/L, rapid mixing speed of 120 rpm and temperature at 30 °C. The experimental data was observed to be close to the model predictions with the optimum turbidity, COD and SS removal efficiencies found to be at 62.81%, 59.57% and 57.23%, respectively.

Textile dyeing wastewater becomes one of the root causes of environmental pollution. Titanium dioxide (TiO2) is one of the photocatalysts that shows prominent organic dye photodegradation ability. In this study, a porous tungsten oxide (WO3)/TiO2 composite was prepared through ultrasonic-assisted solvothermal technique with varying amounts of WO3 ranging from 0.25 to 5 weight % (wt.%). The prepared 0.50 wt.% WO3/TiO2 (0.50WTi) composite exhibited the highest photodegradation activity (4.39 × 10−2 min−1) and complete mineralization in chemical oxygen demand (COD) reading towards 30 mg.L−1 of Reactive Black 5 (RB5) dye under 60 min of light irradiation. Effects of large surface area, small crystallite size, high pore volume and size, and low electron-hole pair recombination rate attributed to the superiority of 0.50WTi. Besides, 0.50WTi could be reused, showing 86.50% of RB5 photodegradation at the fifth cycle. Scavenger study demonstrated that photogenerated hole (h+) was the main active species of 0.50WTi to initiate the RB5 photodegradation. Cytotoxicity assessment determined the readings of half-maximal inhibitory concentration (IC50) were 1 mg.mL−1 and 0.61 mg.mL−1 (24 and 72 h of incubations) for the 0.50WTi composite.

The microwave enhanced advanced oxidation process (MW-AOP) has been applied to pre-treat different sludge types and high solids content. Secondary sludge not only had the highest solids and nutrient content but also yielded higher treatment efficiency than primary or mixed sludge. In the case of secondary sludge with 4% total solids (TS), the total suspended solids (TSS) concentration was reduced by 32% while soluble chemical oxygen demand concentration increased from 1% to 40% after treatment at 110°C. A high level of nutrient release was also achieved; about 65% total phosphate (TP) solubilized at 110°C. The degree of secondary sludge disintegration was dictated by temperature and hydrogen peroxide dosage. The optimal operating temperature for the system was 110°C, and sludge containing TS up to 8% was treated effectively. Secondary sludge with 8% TS had a TSS reduction of 41% after treatment at 110°C while COD solubilization was about 45%; about 55% TP was solubilized at 10 min holding time. Treatment of sludge with higher solids content would allow for handling larger amounts of sludge at a given period and reduce heating cost per unit of treated sludge. The inter-relationship between the degree of sludge disintegration and changes in chemical and physical properties was also clearly demonstrated here. The treated sludge would be an ideal substrate for anaerobic digestion or phosphorous recovery processes. High levels of nutrients (phosphorus and nitrogen) and metal release, and solids disintegration from sludge containing high solids content would make subsequent resource recovery processes more effective and economical.

Accurate prediction of inlet chemical oxygen demand (COD) is vital for better planning and management of wastewater treatment plants. The COD values at the inlet follow a complex nonstationary pattern, making its prediction challenging. This study compared the performance of several novel machine learning models developed through hybridizing kernel-based extreme learning machines (KELMs) with intelligent optimization algorithms for the reliable prediction of real-time COD values. The combined time-series learning method and consumer behaviours, estimated from water-use data (hour/day), were used as the supplementary inputs of the hybrid KELM models. Comparison of model performances for different input combinations revealed the best performance using up to 2-day lag values of COD with the other wastewater properties. The results also showed the best performance of the KELM-salp swarm algorithm (SSA) model among all the hybrid models with a minimum root mean square error of 0.058 and mean absolute error of 0.044.

This study evaluated and compared the performance of three highly praised high rate anaerobic bioreactors (HRABs), including the expanded granular sludge bed (EGSB) bioreactor, the static granular bed reactor (SGBR), and the down-flow expanded granular bed reactor (DEGBR), for the treatment of poultry slaughterhouse wastewater (PSW) which is characterized by a high concentration in oil and grease, suspended solids, and nutrients. These three bioreactors were operated under mesophilic conditions and followed a similar operational methodology, which consisted of increasing the organic loading rate (OLR) as the bioreactor responded positively to fluctuating organic loads. The response to the fluctuations of the bioreactors was evaluated with respect to the removal of the organic matter contained in PSW at high throughput rate. This study revealed that the three bioreactors performed differently. This dissimilarity in performance was associated with the difference in the configuration of each reactor and the capacity of maintaining a high performance at increased levels of OLR. These configurations are specifically described in this study. Of the three bioreactors that were investigated, the DEGBR performed the best with total chemical oxygen demand (tCOD), biological oxygen demand (BOD5) and fats, oil, and grease (FOG) maximum removal percentages of 99.6%, 99.9% and 99.4%, respectively, for a maximum OLR of 38.9 gCOD/L.day. While the EGSB also provided appreciable results with 99.1%, 99.5% and 97%, for the maximum removal efficiency of tCOD, BOD5 and FOG, respectively. At last, the SGBR achieved tCOD, BOD5 and FOG maximum percentage removal of 97.6%, 99.2% and 97.7%, respectively.

The leather industry has been looking for alternatives to minimize its environmental impacts, including studies to reduce the pollution load of liquid effluents from the leather process. Although studies reducing the supply of chemicals have already indicated optimized offers of fatliquoring and retanning agents, the effect of the scale-up of these optimized conditions on effluents and the quality of the leather remains unknown. This study aims to reduce the pollution load of post-tanning effluents by reducing leather chemicals supply. Tests were performed on pilot and industrial scales, reducing the offer of retanners and fatliquors in two levels: 19% and 26%. The effluents were tested for pH, conductivity, dissolved solids, sulfate, biochemical oxygen demand, and chemical oxygen demand. The leather was tested for organoleptic properties and physical-mechanical tests. The reduction of chemicals allowed the depletion of the raw wastewater pollution load. The leather obtained showed a quality within the established standards. Besides, post-tanning formulation costs were reduced by 24%.

Eutrophication has become a great concern in recent years with the algae blooms in source water resulting in a serious threat posing to the safety of drinking water. Chlorine dioxide (ClO2) has been served as an alternative oxidant for preoxidation or disinfection during drinking water treatment process due to its high oxidation efficiency and low risk of organic by-products formation. However, the generation of inorganic by-products including chlorite (ClO2−) and chlorate (ClO3−) has become a potential problem when applied in drinking water treatment. In this study, ClO2 preoxidation-assisted coagulation/precipitation process was applied to improve the raw water quality, especially algae, turbidity, chemical oxygen demand (CODMn), and UV254, and explore the formation mechanisms of inorganic by-products. It was found that the polymeric aluminum chloride (PAC) and ClO2 have shown the best raw water treatment performance with the optimal dosage of 10 mg/L and 0.8 mg/L, respectively. Moreover, the initial pH also has exhibited a notable influence on pollutants treatment and by-products generation. Due to the adverse influence of algae and natural organic matters (NOM) and the generation of by-products, it was significant to investigate their inhibition effect on the water quality and the production of ClO2− and ClO3− in the ClO2 preoxidation-assisted coagulation/precipitation process. Moreover, it was applicable of this process to apply for the algae-containing raw water (calculated as Chl.a lower than 50 μg/L) treatment with the ClO2 dosage of less than 0.8 mg/L to achieve optimum treatment performance and minimum by-products generation.

The colossal amount of hydrocarbon-rich sludge generated from effluent treatment plants of petroleum refineries has enormous potential for methane-rich biogas production. The biodegradation of petroleum refinery biosludge (PRB) was compared between undigested residue (UR) and anaerobically acclimated or digested sludge (DS) from an anaerobic reactor at five different inoculum:sludge ratios (0.3, 0.4, 0.5, 0.7, 1.0 based on volatile solids content). Upon performing batch anaerobic degradation assay tests, methanogen-rich DS provided a better seeding environment with maximum methane yield being attained at ratio DS:PRB = 0.5. The long hydrolysis phase of the complex hydrocarbon substrate was intended to be improved through the optimization of different modes of heat application (dry heat, pressurized moist heat, agitated open moist heat and microwave irradiation). The best mode was dry heat which when applied at 140 °C for 60 min improved soluble chemical oxygen demand and fatty acids concentration of untreated sludge by 2.28 and 1.3 folds respectively. Dry heat application enhanced methane production by 24.8 % with 48.7 % organic matter removal in presence of DS as inoculum. Morphological and chemical characterization corroborated the fragmentation of aliphatic hydrocarbon bonds through dry heat application. Positive energy recovery (21,826 kJ) from PRB upon dry heat pretreatment evinces its feasibility at a larger scale. The presence of toxic organic pollutants was confirmed by Gas Chromatography–Mass Spectroscopy (GC–MS) analysis and the phytotoxicity assay using V. radiata showed concentration-dependent decrease in seed germination, shoot length, root length and biomass after the digestion process in comparison to control thereby, suggesting a sustainable and promising method to petrochemical industries for utilization and transformation of such toxic hydrocarbon-rich sludge into a renewable energy source.

In this study, we explored the ability of wild-Serbian Ganoderma lucidum mycelial pellets (GLMPs) in treating synthetic domestic wastewater in a batch reactor under various operating conditions. The GLMPs produce non-hazardous by-products, are environmentally sustainable and able to produce in mass bulk with consistent quality. Riding on the highly efficient of treatment of industrial (textile) wastewater using GLMPs, similar high efficiency is foreseen for domestic wastewater as a green alternative treatment process. The optimal performance of GLMPs in similar synthetic domestic wastewater with a Carbon-to-Nitrogen (C/N) ratio of 16.7:1 was evaluated under three operational conditions. The C/N ratio was chosen based on the urban domestic wastewater characteristic during high peak flow with an initial Chemical Oxygen Demand (COD) of 533 mg/L and ammonia–nitrogen (NH3–N) content of 30 mg/L. The operational parameters of agitation speed (0 rpm, 25 rpm, 50 rpm, and 100 rpm), environmental temperature (25 °C, 30 °C, 35 °C, and 40 °C), and GLMP inoculum percentage (GIP) (0%, 0.25%, 0.50%, 0.75%, and 1.00%) were chosen for the experiment. In the experiment, the agitation speed of 100 rpm and the environmental temperature of 25 °C showed the best performance of the GLMPs within 15 h of retention time with a percentage removal of 92.9% for COD and 93.8% for NH3–N. Furthermore, a high volume of GIP in the batch reactor had an insignificant impact on the performance in the same concentration of wastewater, and 0.25% GIP was the volume used to treat the domestic wastewater.

The purpose of this study is to evaluate the impact of several pre-selected carrier materials used in an Inverse Fluidized Bed Reactor (IFBR) on the treatment efficiency of distillery spent wash water. Distillery spent wash water has been identified as a threat to the natural environment due to its high pollution load. The effluents from the industry are dark brown in color and contain heavy organic matter, causing a high Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD); however, they can be treated effectively through biological processes. Previous research reveals that a high-rate anaerobic digester especially an IFBR reduces COD more effectively than other treatment technologies. The effectiveness of the reactor depends on the expansion of the fluidized bed which in turn is related to the carrier material. In this study, four different carrier materials: perlite, expanded perlite, sawdust and polystyrene, were selected. The carrier materials selected were assessed based on their efficiency in reducing COD, Total Solids (TS), Total Dissolved Solids (TDS) and Total Suspended Solids (TSS). Results were taken at 140-h Hydraulic Retention Time (HRT), with a constant Organic Loading Rate (OLR) of 12 kg COD/m3/day. Among the selected carrier materials, expanded perlite was most effective at reducing COD, TS, TDS and TSS (83.33, 72.47, 29.67 and 88.78%, respectively). This method could be easily implemented in industrial practice and thereby reduce the negative impact of production plants on the natural environment.

Wastewater discharge from the leather manufacturing process involves various operations such as beam house, tanning and post-tanning. The conventional treatment system does not efficiently treat these kinds of wastewaters without the generation of any secondary pollutant. Mostly vast quantities of chemicals are added to the wastewaters to adjust pH to favour the treatment units that results in a huge amount of primary chemical sludge. This paper reports a new treatment approach by mixing various tannery operational wastewaters in the appropriate treatment units to adjust pH instead of adding chemicals. It also designed a treatment sequence to simultaneously treat all tannery operational wastewaters in such a way to suit their biodegradability and to avoid sludge to a greater extent. The treated water resulted in biochemical oxygen demand, 58 ± 39 mg L−1; chemical oxygen demand, 305 ± 35 mg L−1; total organic carbon, 94.93 ± 45.46 mg L−1; total nitrogen, 295 ± 226 mg L−1; ammoniacal nitrogen, 146 ± 75 mg L−1.

This study employed two batch-type bioreactors for the treatment of twelve environmental contaminants with the potential to disrupt the normal function of the endocrine system. The contaminants included bisphenol A, two alkylphenols, two hormones, six organochlorine pesticides and one organophosphate pesticide. Synthetic domestic wastewater was prepared daily in the laboratory and fed to the bioreactors. The bioreactors were operated at two different sludge retention times and the parameters used to evaluate their performance were chemical oxygen demand, ammonium, orthophosphate, pH, temperature, dissolved oxygen and mixed liquor suspended solids. Upon reaching optimum operational conditions, the analytes were spiked into the bioreactors and the removal efficiencies were calculated with respect to the influent concentration. Satisfactory removal efficiencies (> 88%) were recorded for all twelve analytes as validated by the decline in ammonium, chemical oxygen demand and orthophosphate amounts. Sludge samples from the two bioreactors were analyzed at the end of the study, but none of the analytes was detected according to the detection limit of the method. The simple and efficient bioreactor system reported in this study was successfully used to remove twelve different endocrine disrupting compounds from wastewater, and this can be easily replicated with low financial cost.

Carwash wastewater treatment with potassium ferrate (VI) (K2FeO4) was optimized by response surface methodology. The optimum conditions for chemical oxygen demand removal were established a pH 3.5, 0.328 g/L dose of K2FeO4, and with a process duration of 48 min. At these conditions, chemical oxygen demand, total organic carbon, total nitrogen, and total phosphorus decreased by 70.3, 58.9, 73.3, 82.0%, respectively; and the putrid odor was reduced. Simultaneously, the total viable count, total coli count, most probable number of fecal enterococci, and the total proteolytic bacteria count decreased by 89.5, 93.1, 92.9, and 95.0 %, respectively. Comparatively, an application of 0.450 g/L FeCl3·6H2O corresponding to the iron content in 0.328 g/L of K2FeO4 resulted in a decrease of total viable count, total coli count, most probable number of fecal enterococci and the total proteolytic bacteria count only by 38.1, 31.2, 42.9, and 58.0%, respectively. Therefore, flocculation with polyacrylamide anionic flocculant combined with potassium ferrate (VI) oxidation is a more effective alternative to coagulation with FeCl3 and the same flocculant. The use of potassium ferrate (VI) is a viable option for the treatment of carwash wastewater.

Leachate produced from hazardous waste landfills has been observed to exhibit very complex characteristics including the presence of a high amount of refractory organics and toxic elements which make it unfit for conventional treatment. This study is focused on the characterization and treatability of “hazardous waste landfill leachate” through electrocoagulation for the reduction of chemical oxygen demand (COD). Effect of different operating parameters, such as electrode material, interelectrode distance (IED), current density (CD), and electrolysis time (ET), has also been studied. For galvanized iron (GI) electrodes, a significant reduction in phenolic compounds, cadmium, lead, and zinc concentration was observed and more than 80% reduction in COD and color was achieved on a bench-scale reactor for a CD value of 41.64 A/cm2 at IED of 1.5 cm and for ET equating to 240 min. Substantiated by experimental results and statistical analysis like ANOVA and post hoc analysis, it appears that electrocoagulation is a proficient technology for the treatment of hazardous waste landfill leachate which has a huge potential for further research.

The effect of bioreactor configurations on the dynamics of aeration modelling was investigated by incorporating three different correlations from the literature to estimate α-factors into the aeration model. Estimated air flow rates using the three correlations were then validated against experimental data obtained from pilot sequencing batch reactors (SBRs). Two identical SBRs were operated in parallel; one received raw wastewater and the other received primary treated wastewater. The validated aeration model was then used to evaluate aeration dynamics in different bioreactor configurations, both for nitrification only and nitrification/denitrification, with the three different correlations. The current study is the first to investigate the validity of the aforementioned correlations using various bioreactor configurations and to establish that the bioreactor configuration not only impacts spatial and temporal biological oxygen demands as currently understood but also oxygen transfer efficiency. The first correlation based on the real-time bioreactor soluble chemical oxygen demand (sCOD) was able to predict the temporal measured air flow rate in the pilot SBRs. The second correlation based on the influent COD overestimated the air flow rates as it considered the impact of the influent loading rates on the α-factor and overlooked the improvement in α-factor due to biodegradation. The third correlation based on MLSS concentrations underestimated the air flow rates at the beginning of the aeration cycle as it ignored the impact of influent loading rates on the α-factor and considered only the insignificant change in MLSS during the aeration cycle. In terms of bioreactor configuration, the model-based analysis showed that the first correlation is suitable for designing SBR, plug flow reactor (PFR), step-feed PFR, and completely mixed stirred reactor (CSTR) systems, and the third correlation is suitable for designing CSTRs and membrane bioreactors (MBRs), while the second correlation was not accurate in any of the reactors modelled. When nitrification was targeted, the CSTR reduced aeration energy by 44 %–49 % compared to the PFR, and 41 %–43 % when both nitrification and denitrification were targeted. Compared to the plug-flow reactor, the step-feed PFR reduced aeration energy by 9% when nitrification only was targeted. However, when pre-denitrification was added, both systems showed the same aeration energy consumption. Pre-denitrification reduced organic loadings to aeration tanks and decreased aeration energy by 22 %, 11 %, 15 %, and 14 % in PFR, CSTR, PFR step feed and MBR systems, respectively.

Refinery effluents represent an emission source of hydrocarbons (HCs) and other constituents to the environment. Thus, characterisation of effluent quality in terms of concentrations of key parameters relative to permitted standards is important and for total petroleum hydrocarbons (TPH), the specific composition of the HC mixture can affect its toxicity to aquatic organisms. Therefore, this study was designed to analyse TPH, benzene, toluene, ethyl benzene, xylenes (BTEX), polycyclic aromatic hydrocarbons (PAHs), (bio) chemical oxygen demand, total nitrogen, total suspended solids and selected metals before, and after, treatment steps to demonstrate removal efficiencies across 13 refineries with variable wastewater treatment systems. Final discharge concentrations of the measured parameters were by 97% within the so called Best Available Technique Associated Emission Levels (BAT-AELs). Further, TPH composition was characterised using high-resolution two-dimensional gas chromatography (GCxGC) analysis to understand the mass distribution by carbon number and specific chemical class. Measurements were compared to SimpleTreat model predictions for validation. SimpleTreat successfully predicted the shape of the effluent composition since it is essentially a removal constant applied to the influent composition. The predictions were of similar magnitude as, or were greater than, the effluent concentrations since SimpleTreat is based on typical performance and is intended to be conservative. This was especially true for aromatic constituents. Reduction in potential HC exposures also coincided with a decrease in predicted toxicity using a mechanistic oil toxicity model, PETROTOX. Overall, the results indicate that EU petroleum refineries are likely to achieve a high performance level regarding effluent treatment.

In this study, a sequential process (heterotrophic up-flow column and completely mixed membrane bioreactors) was proposed combining advantages of the both processes. The system was operated for 249 days with simulated and real groundwater for nitrate removal at concentrations varying from 25 to 145 mg·L−1 NO3−-N. The contribution of heterotrophic process to total nitrate removal in the system was controlled by dozing the ethanol considering the nitrate concentration. By this way, sulfur based autotrophic denitrification rate was decreased and the effluent sulfate concentrations were controlled. The alkalinity requirement in the autotrophic process was produced in the heterotrophic reactor, and the system was operated without alkalinity supplementation. Throughout the study, the chemical oxygen demand in the heterotrophic reactor effluent was (23.7 ± 22) mg·L−1 and it was further decreased to (7.5 ± 7.2) mg·L−1 in the system effluent, corresponding to a 70% reduction. In the last period of the study, the real groundwater containing 145 mg·L−1 NO3−-N was completely removed. Membrane was operated without chemical washing in the first 114 days. Between days 115–249 weekly chemical washing was required.

The rapid expansion of urban areas has given rise to the generation of large amounts of wastewater that pose a growing pressure on the surrounding ecosystems. Effective water quality surveillance programs demand the implementation of in-field tests to monitor water safe discharge in the environment after being adequately treated. This paper describes the manufacturing and application of a miniaturized electrochemical sensor for measuring dissolved chemical oxygen demand (COD) in surface waters entering and exiting urban wastewater treatment plants (UWWTP). Thin-film carbon electrodes are produced on Si/SiO2 substrates by a combined sol–gel material synthesis and photolithography/dry etching process at the wafer level and show superior electrochemical performance compared with the glassy carbon standard electrode. Three-electrode electrochemical cells of planar configuration are produced and the COD sensor is manufactured by electrodepositing copper nanoparticles (Cu NPs) on the working electrode under controlled potentiostatic conditions. A simple fluidic electrochemical sensor device is fabricated and allows for the Cu NPs electrodeposition as well as analytical sensor performance in an automatic fashion. A linear range up to 670 mg·L-1 O2 and a limit of detection of 30 mg·L-1 O2 are achieved. The ability of this electrochemical sensor approach to monitoring the soluble organic load of urban wastewater in real-time is evaluated by analyzing three samples collected in different locations of an UWWTP. The COD values estimated with the sensor are in excellent agreement with those obtained using the standard dichromate method provided by an accredited laboratory. This analytical platform provides a robust, user-friendly low-maintenance flow sensor approach for deployed analysis of COD that could aid to control the effectiveness of water treatment processes, especially when facing water influents containing organic overloads due to changing weather conditions or any anthropogenic phenomena., The Chinese Scholarship Council fellowship (201806220063) to W.C. Duan is acknowledged. WD is enrolled in the Materials Science PhD Program of the UAB (Universitat Autònoma de Barcelona). This work has also received funding from the EU Horizon 2020 framework programme under the Marie Skłodowska-Curie grant agreement No 801342 (Tecniospring INDUSTRY)” and the Government of Catalonia's Agency for Business Competitiveness (ACCIÓ). The Spanish Ministry of Science and Innovation is acknowledged for financial support through the Severo Ochoa programme for Centers of Excellence in R&D (CEX2019-000917-S). Some additional funding was also given by the government of Catalonia, with grants numbers 2017 SGR 1771 and 2017 SGR 765. The X-ray diffraction and thermal analysis laboratories of the ICMAB scientific services contributed to this work and are acknowledged. This work used the Spanish ICTS Network MICRONANOFABS which was partly supported by the Spanish Ministry of Science and Innovation. We are very grateful to Mercè Baldi and Josefina Torán for their help and for kindly providing us with the real water samples from the wastewater treatment plant., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Water shortages make the reclaimed water widely used in urban parks. Due to the residual pollutants, phytoremediation is often carried out in water bodies. In this study, an urban park was selected to study the practical effects of phytoremediation by comparing the water quality in different seasons and water areas. Chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH4+–N), total phosphorus (TP), and dissolved organic matter (DOM) were detected. The spatial analysis of pollutants was performed using kriging interpolation in Arc GIS. Hydrophytes species and planting area were also investigated. The results showed that phytoremediation effectively reduced the concentrations of TN and TP in waters all year round. Except in summer, phytoremediation also presented excellent removal of COD and NH4+–N. However, the removal effects of COD and NH4+–N were relatively inadequate in summer due to the rainfall and runoff. Submerged plants played a more important role than emerged plants in water restoration. Especially in winter, the growth of submerged plants guaranteed the removal of nutrient substances. Parallel factor analysis of fluorescent spectra displayed three components in the DOM, namely tryptophan-like (C1), humic-like (C2), and tyrosine-like substances (C3). The spring samples contained C1 and C2, while there was additional C3 in summer samples. The fluorescence intensities of C1, C2, and C3 were stronger in the area with higher plant density, which also reflected the high number of adsorbed microorganisms and was beneficial to degradation and removal of pollutants.

Nitrogen (N) removal from stormwater runoff prior to its export to sensitive downstream water bodies is a common goal for urban stormwater ponds (SWPs). Denitrification removes nitrate (NO3−) from stormwater runoff by conversion to di-nitrogen gas (N2), permanently removing reactive N from the ecosystem. Typically, N removal in SWPs is quantified via mass balance approaches, but the internal biogeochemical mechanisms driving N dynamics in these engineered ecosystems are unclear. In this study, we quantified gaseous and dissolved inorganic N fluxes and sediment oxygen demand from sediment cores collected at residential SWPs ranging from 10 to 30 years old in two subtropical cities during the dry and wet seasons. To better understand biogeochemical process rates and drivers within SWP sediments, we exposed sediments to both ambient and elevated (to simulate stormwater runoff) water column nitrate concentrations. Under ambient concentrations, SWP sediments could be either net sources (via N-fixation) or sinks (via denitrification) for N, and net N2 flux was not significantly affected by background nitrate concentrations, sediment oxygen demand, or age. However, SWP sediments shifted to net denitrification under elevated nitrate conditions. Denitrification (positive net N2 flux) increased with SWP age, microbial activity, and net nitrate uptake (p

Constructed wetlands (CWs) have great potential as low-cost natural wastewater treatment in developing countries. The present study appraises the performance of the vertical flow constructed wetland for domestic wastewater treatment. More specifically, the potential of Canna Indica in the removal of carbon, nitrogen, and phosphorus (CNP) from wastewater under tropical conditions. CW cell was fabricated with a vegetative layer of Canna Indica and tested with domestic wastewater. Based on the test results, Canna Indica shows a high Removal Efficiency (RE) of Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD5) on the order of 87% and 91%, respectively. Similarly, nutrients removal efficiency for total nitrogen (TN), total phosphorus (TP) was found to be 97% and 98%, respectively. The investigation also revealed that there is considerable removal of sulfates with efficiency equal to 78.4%. Overall, the Canna Indica based CWs were found to be suitable for wastewater treatment in the tropical regions, provided a viable medium for treating the wastewater in peri-urban and rural areas of developing countries. Novelty statement This study investigates the performance of Canna indica based vertical flow wetlands for greywater treatment. The study investigates the results at different hydraulic retention times and loading rates.There are no much studies reporting the performance of this variety of plant species under a tropical humid climate.The results from the study can encourage adoption of this plant variety, indigenous to this part of the country, for wastewater treatmentHighlightsIt could emphasize the importance of familiarity with constructed wetlands to comprehend the RE of various climatic zones.It is possible to highlight the Canna-based CW's efficiency in removing organics and nutrients from domestic wastewater.The possibility for field-scale Canna-based CW to remove pollution in tropical climates was investigated, andDecentralization of wastewater treatment at the household level to apply CWs that will improve wastewater quality.

This study aims to identify the role of design and operational parameters in energy costs for a wastewater treatment plant in a meat processing industry regarding water-energy nexus. In the study, the energy cost index has been calculated using a derived numerical approach. This study recommends a new comprehensive methodology for energy cost estimation for an industrial wastewater treatment plant. The model is developed based on organic load, amount of wastewater, and energy consumption required to treat wastewater. Particularly, the impact of design and operational organic load parameters on energy costs has been investigated in this study. Biological oxygen demand (BOD) and chemical oxygen demand (COD) have been regarded as organic load indicators. The results show that the energy cost index of operational organic load is higher than that of the design for two parameters. Energy costs of COD removal are higher than BOD removal. The costs of COD removal are 726.6 and 65,520 €/m3 wastewater for design and operational conditions, respectively, whereas the energy costs related to BOD removal are 90.9 and 7224 €/m3 wastewater for design and operational conditions, respectively. Operational COD removal leads to maximum energy costs for the plant. The lowest energy cost is related to BOD removal of design conditions. In terms of water-energy nexus, wastewater reuse could be considered to reduce energy costs. The possibility of wastewater reuse as boiler feed water has been reported as 50.38%. According to the simulated results, energy costs could be minimized at approximately 49% if wastewater reuse were applied in the plant.

Ecotoxicological assessment of landfill leachate has become a priority to determine its impacts on the ecosystem. Toxicity assays with microorganisms stand out due to their quick response, low cost and ease of testing. In this context, the present study evaluated the acute toxic effects of leachates from two landfills of different ages and modes of operation to bacterium A. fischeri and activated sludge microorganisms and the ammonia nitrogen and humic substances (HS) sensitivity to these organisms. Reductions greater than 30% in leachate toxicity were observed after ammonia removal for A. fischeri and activated sludge microorganisms. After 97% removal of HS, the greater reductions in toxicity (44.28 to 79.82%) were verified for microbial species studied, indicating that the organic compounds (measured as chemical oxygen demand, total organic carbon and humic substances) were the primary pollutants responsible for the toxicity of the leachates. Concerning the organisms studied, A. fischeri showed greater sensitivity to the leachates' pollutants compared to the activated sludge microorganisms. Nevertheless, a strong correlation was observed between A. fischeri and activated sludge microorganisms' toxicity responses, suggesting that respirometry assay can be used to determine leachate toxicity.

This study examines the integrated electro-coagulation–electro-oxidation (EC–EO) process as an alternative for the treatment of an industrial effluent originating from a soluble coffee production. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes was employed (EC: anode: iron and cathode: stainless steel; EO: anode: boron-doped diamond-Si and cathode: stainless steel), operating in galvanostatic mode. The effect of main operation parameters on decolorization, chemical oxygen demand (COD) and total organic carbon (TOC) degradation and total operation costs was studied. The experimental design, analysis of variance, response surface methodology and constrained optimization algorithms let to establish the most effective operation conditions as follows: for EC (support electrolyte = 4.32 g of Na2SO4/L; current density (J) = 150 A/m2; gap between electrodes = 3 mm; stirring velocity = 350 RPM; electrolysis time (t) = 60 min; and EC’s initial pH (pHi, EC) = 4.71 (the pH of raw wastewater)); and for EO (J = 300 A/m2; t = 100 min; gap between electrodes = 3 mm; stirring velocity = 125 RPM; and pHi, EO = 7.0). The integrated EC–EO process let to accomplish ca. 98% decolorization, ca. 73% of both COD and TOC removal, more oxidized (Average Oxidation State = 0.149), biocompatible (BOD5/COD ratio = 0.404) and less toxic effluent (median lethal concentration of an analyte which causes 50% population death, LC50 lower than 126.43 ppm of raw wastewater), generating 3.782 g/L of sludge, with total operation costs of 8.43 USD/m3. During EC, contaminants with molecular weight (MW) higher than 30 kDa were effectively decomposed. The integrated EO process additionally let to break down pollutants with MW in the range of 5 to 10 kDa. The EC–EO total operation time of 160 min. was required to meet Colombian permissible discharge limits.

A new multi-point inflow pre-anoxic/oxic/anaerobic/anoxic/oxic (A1/O2/A3/A4/O5) sludge-membrane coupling process and pilot plant were developed and designed to solve the problem of nitrogen and phosphorus removal of low carbon and nitrogen (C/N) ratio domestic sewage in southern China. The removal effect and transformation rule of organic matter, nitrogen, and phosphorus in the system were studied by changing the distribution ratio of multi-point influent. The average C/N ratio of the influent was 2.09 and the influent distribution ratio was 1:1. When the temperature was 16–25 °C, the average concentrations of chemical oxygen demand (COD), ammonia nitrogen (NH4+- N), total nitrogen (TN), and total phosphorus (TP) in the effluent were 21.31 (±2.65), 0.60 (±0.24), 12.76 (±1.09), and 0.34 (±0.05) mg/L, respectively, and their average removals are 87.3 (±1.2)%, 98.7 (±0.4)%, 74.1 (±1.3)%, and 88.1 (±0.4)% respectively. When the low temperature was 12–15 °C, the average removals were 78.6 (±1.1)%, 90.5 (±1.3)%, 73.7 (±1.13)%, and 86.6 (±1.7)%, respectively. Compared with the traditional anaerobic/anoxic/aerobic (A2O) process under the same conditions, the TN removal was increased by 15.4%, and the TP removal was increased by 22.2%. This system has obvious advantages in treating wastewater with low C/N ratio, thereby solving the problem wherein the effluent of biological phosphorus removal from low C/N ratio domestic sewage was difficult when it was lower than 0.5 mg/L.

Sewage treatment plants (STP) in Malaysia are designed to treat a load of contaminants according to the level of concentration for chemical oxygen demand (COD) and nitrogen ammonia (NH3-N) of 250 mg/L and 30 mg/L, respectively. However, studies show that the organic load of Malaysian wastewater is low and even temporarily fluctuates resulting in the low effectiveness of treatment especially in ammonia removal and consequently cause effluents that do not undergo proper treatment to be released into the environment. Therefore, this study aims to identify concentrations of COD and NH3-N in the influent of urban domestic wastewater along with other physico-chemical characteristics. Two locations of the STP were chosen based on the urban area with different catchment sizes for a population equivalent (PE) 60,000 for the first STP (LRK#1), and 150,000 for the second STP (LRK#2). These parameters include pH, temperature, conductivity, turbidity, total suspended solids (TSS), nitrogen nitrate (NO3-N), total Kjeldahl nitrogen (TKN) as well as heavy metals such as Cadmium (Cd), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), and Zinc (Zn). The sampling and analysis methods used the guidelines recommended in the American Public Health Association (APHA). The results give the highest average COD concentrations for the LRK#1 and LRK#2 are 180.5 mg/L and 380.9 mg/L, respectively. The highest NH3-N concentrations were 33.53 mg/L for LRK#1 and 31.63 mg/L for LRK#2. Overall, the wastewater physico-chemical characteristics of both treatment plants show wastewater in the medium and low concentration categories.

Hamburger seed coat is a readily available agricultural waste product generated in large quantities annually. In this study, activated charcoal was produced using hamburger seed coat activated with zinc chloride and its physicochemical properties such as fixed carbon, specific surface area, volatile matter, ash and moisture content were investigated. Scanning electron microscopy and Fourier transform infrared spectrometry techniques were used to study the surface morphology and variations in the absorption bands of functional groups, respectively. The adsorbent biosorption of pollutants abilities from contaminated water was investigated using standard methods with a view to ascertaining the adsorbent purification potential. The results showed that the adsorbent was of high porous structure with adsorption capacity significantly correlated with iodine value. The physicochemical properties of the contaminated water treated with the adsorbent were comparable with commercial activated charcoal (control)-treated water but indicated a significant decrease (p

This paper aimed to develop a new photocatalytic reactor design with a rotary tree branch structure for wastewater treatment in the textile industry. The brass sheet calcined at 500 °C (B500) was used as the photocatalyst and as a substrate for ZnO nanoparticle immobilization (B500ZnO). The photoreactor performance was evaluated toward the photodegradation of an aqueous solution of Reactive Black 5 dye (AS-RB5), raw wastewater (RW), and treated wastewater (TW). X-ray diffraction (XRD) and scanning electron microscopy (SEM) results illustrated ZnO nanowire formation over B500 and B500ZnO substrates. The bandgap values of these samples were estimated by diffuse reflectance measurements. The effects of dye concentration, the type of radiation, and ZnO NP deposition on the degradation of AS-RB were evaluated. Decreases in chemical oxygen demand (COD) greater than 82% were obtained using solar irradiation and artificial light as the energy source. Regarding calcined brass sheet reutilization, a decrease of 45% in the photocatalytic activity efficiency after 5 cycles was noted due to the effect of photocorrosion of the ZnO nanowires. The photoreaction of the RW and TW effluents showed COD values of 21 and 35%, respectively, which are below the limits established by state environmental control. With respect to RB5 addition to the TW effluent (TW-RB5), a discoloration of 62% was noticed after 3 h of photodegradation. Furthermore, the toxicity tests of the AS-RB5 and TW-RB5 samples did not display toxic intermediates after the photoreaction since 80% of the seeds germinated. Finally, the photoreactor exhibited good performance regarding the decrease in effluent pollutant charge, in addition to the efficient discoloration of RB5 dye.

Petrochemical industrial wastewater presents a challenge when treated, employing the conventional activated sludge process, such as in the activated sludge process, the loss of biomass due to the harsh wastewater conditions and the inhibition caused by the elevated levels of industrial compounds. Hybrid biological reactors may present a resource to be tapped in the operation of an industrial wastewater treatment facility if integrated optimally in the treatment sequence. This paper examines possible integration scenarios of hybrid reactors in a petrochemical wastewater treatment plant in order to improve its organic removal efficiency. A pilot hybrid biological reactor was constructed using high surface area biological carrier and was operated using real wastewater streams from a wastewater treatment plant at two flow rates (400 ml/min and 240 ml/min), two dissolved oxygen levels (2.0 mg/l and 4.0 mg/l), and anaerobic conditions. The reactor was tested using raw, primary, secondary, and effluent streams from the wastewater treatment plant. The reactors were primed with wastewater from the aeration tank of the wastewater treatment plant and was operated for 10 d afterward (total 24 runs). The chemical oxygen demand cumulative removal was used to identify best integration scenario and to benchmark its performance against domestic wastewater. The best performing scenarios were identified as anaerobic (400 ml/min) for raw wastewater treatment and [(400 ml/min and dissolved oxygen (DO) 2.0 mg/l)] for secondary wastewater polishing. The results reflected the unfavorable conditions for biodegradation after the primary chemical treatment. This conclusion was confirmed upon benchmarking the hybrid reactor performance using domestic wastewater.

Anaerobic codigestion (AcD) of agroindustrial residues was investigated. Granular sludge from bench-scale bioreactors digesting different manure were acclimated and recycled as microbial seed sludge to demonstrate inoculum-type influence on digestion performance. The biomethane potential (BMP) assay was operated for 30 days at 40 ± 2 °C in batch-type laboratory-scale reactors (100 mL). In inoculum amended reactors, codigestion showed significant, yet distinctive, biomethanation than monodigestion with a 5-fold increase (p