Chemical Oxygen Demand Reduction Efficiency Research Articles

Performance and microbial community composition of full-scale high-rate cascade sludge digestion system via pie-shaped reactor configuration

A full-scale high-rate cascade anaerobic digestion (CAD) system was evaluated for its ability to enhance enzymatic sludge hydrolysis. The system included a newly built digester, innovatively divided into three pie-shaped compartments (500 m3 each), followed by an existing, larger digester (1500 m3). The system treated a mixture of waste activated sludge and primary sludge, achieving a stable total chemical oxygen demand reduction efficiency (56.1 ± 6.8 %), and enhanced sludge hydrolytic enzyme activities at a 14.5-day total solids retention time (SRT). High-throughput sequencing data revealed a consistent microbial community across reactors, dominated by consortia that govern hydrolysis and acidogenesis. Despite relatively short SRTs in the initial reactors of the CAD system, acetoclastic methanogens belonging to Methanosaeta became the most abundant archaea. ‬‬‬‬‬‬‬‬‬‬‬‬‬ This study proves that the CAD system achieves stable sludge reduction, accelerates enzymatic hydrolysis at full-scale, and paves the way for its industrialization in municipal waste sewage sludge treatment.

Application of electro oxidation process for treating wastewater from petrochemical with mixed metal oxide electrode

Petrochemicals require a large volume of water for their operation, which results in the production of a large volume of wastewater. Treatment of petrochemical wastewater is an important process before discharging it into the environment. This research examines the treatment of real petrochemical wastewater using the electrochemical oxidation process. Direct anodic oxidation is an effective advanced electrochemical oxidation process (AEOP), with different electrodes using a parallel plate electrochemical reactor. Four types of real wastewater were received from different petrochemical units were treated by AEOP. Real wastewater samples with chemical oxygen demand (COD) concentrations ranging from 20,450 to 52,300 mg/l. The main goal of this research is to make electrodes of Mixed Metal Oxide (MMO), which can reduce the treatment time and electricity consumption for oxidation, greater stability of the surface of the electrodes. Investigation of the rate constant kinetics shows that high COD removal efficiency can be achieved following the pseudo-second order reaction rate (R2 > 98%). When the wastewater pH is less than 5, COD removal efficiency is higher and the treatment process will be successful, which succeeded in removing 79% COD, but in alkaline wastewater, COD reduction efficiency was not satisfactory. The electricity consumption for 79% removal during 6 min was 117 kWh/m3. As a result, due to the very short time of the process (6 min), it can be used as one of the pre-treatment steps of petrochemical wastewater with acidic pH.

Microalgae as A Bioremediation Agent for Palm Oil Mill Effluent: Production of Biomass and High Added Value Compounds

Palm oil mill effluent (POME) is high strength wastewater obtained from palm fruit processing, which contains high chemical oxygen demand (COD), biological oxygen demand (BOD), and other contaminants. The pollutant load in POME can serve as a source of nutrients for microalgae growth. As a result, the goal of this work was to utilize Spirulina sp. and Nannochloropsis oculata to reduce the nutritional content of POME while producing biomass rich in high-value chemicals. The cultivation was conducted in a batch reactor using various POME fractions (0-20%) under 5,000 lux light intensity and continuous aeration at a temperature of 22-28°C and a salinity of 30 ppt for 14 consecutive-days. The results demonstrate that Spirulina sp. produced the most biomass at 15% POME, accounting for 4.67±0.95 g/L with 0.57±0.11 1/day of growth rate and 3.33% of COD reduction efficiency. Meanwhile, Nannochloropsis oculata thrived in 20% POME, producing 4.43±0.36 g/L biomass, 1.18±0.31 1/day growth rate, and 14.43% COD reduction efficiency. In the proximate analysis. Spirulina sp. and Nannochlorpsis oculata provided 0.87%; 1.11% lipid and 1.03%; 0.86% protein, respectively.

Exploring the potential of thermophilic anaerobic co-digestion between agro-industrial waste and water hyacinth: operational performance, kinetic study and degradation pathway.

Anaerobic co-digestion (co-AD) of agro-industrial waste, namely, palm oil mill effluent (POME) and sugarcane vinasse (Vn), with water hyacinth (WH) as co-substrate was carried out in two separate Anaerobic Suspended Growth Closed Bioreactors (ASGCBs) under thermophilic (55°C) conditions. The highest chemical oxygen demand (COD) and soluble COD reduction in co-AD of POME-WH (78.61%, 78.86%) is slightly higher than co-AD of Vn-WH (75.75%, 78.24%). However, VFA reduction in co-AD of POME-WH (96.41%) is higher compared to co-AD of Vn-WH (85.94%). Subsequently, biogas production peaked at 13438mL/day values and 16122mL/day for co-AD of POME-WH and Vn-WH, respectively. However, the methane content was higher in the co-AD of POME-WH (72.04%) than in the co-AD of Vn-WH (69.86%). Growth yield (YG), maximum specific substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) are higher in co-AD of POME-WH, as supported by the higher mixed liquor volatile suspended solids (MLVSS) and COD reduction efficiency compared to co-AD of Vn-WH. However, methane yield ([Formula: see text]) reported in the co-AD of POME-WH and Vn-WH are 0.2748 and 0.3112 L CH4/g CODreduction, respectively, which suggests that WH is a more suitable co-substrate for Vn compared to POME.

Allowance of Laundry Wastewater Contaminant Parameters by Electrocoagulation Process

The laundry business is one of the household-scale businesses that is currently developing in Jambi City. This is possible because the number of laundry business customers is increasing along with the increase in the population in the city of Jambi and the increasingly diverse activities of the people of the city of Jambi. The laundry business in Jambi City is more than 300 units, so if the laundry waste is not treated first, it will have the potential to cause environmental pollution because of the compounds it contains. This study aims to determine the efficiency of the electrocoagulation process to decrease parameters in laundry wastewater, while the parameters observed are pH, COD (Chemical Oxygen Demand), and Phosphate (PO4). Cause pollution to the surrounding environment, especially in receiving water bodies. Variable voltage (voltage) in the electrocoagulation process is 9 volts, 12 volts, and 15 volts with a reactor capacity of 12 liters with a time of 30 minutes and 60 minutes at each voltage. Decreasing parameters were analyzed by comparing pH, COD (Chemical oxygen demand), and Phosphate (PO4) before and after the study, as well as the effect of voltage (voltage) and contact time on the effectiveness of decreasing parameters. The highest percentage of COD reduction efficiency is 80%, Phosphate Parameter is 92%. Voltage (voltage) and contact time also affect the results of parameter removal.

Use of Shredded Recycled Plastic as Filter Bed Packing in a Vertical Flow Filter for Onsite Wastewater Treatment Plants: Preliminary Findings

Household wastewater is a problem, especially in areas with a dispersed settlement where there is no wastewater collection system or wastewater treatment plant. In this case, it is necessary to build a local or onsite wastewater treatment plant. This paper is an attempt to analyse the possibility of using recycled shredded ABS plastic (acrylonitrile butadiene styrene) as packing media in an experimental vertical flow filter for use in on-site wastewater treatment plants. Studies have shown that shredded recycled ABS is a promising filtration material that has several features important in the treatment process, like a large surface area, high mechanical strength and chemical inertness. The system was operated with a hydraulic load of 50 dm3/m2 (3 months). BOD5 (biochemical oxygen demand), COD (chemical oxygen demand), and total suspended solids (TSS) reduction efficiency in the primary effluent was high; 94.4%, 77.8%, and 92.8%, respectively.

Mineral Pumice Efficiency in Wastewater Treatment in Dairy Industries

Abstract In this study, the effectiveness of mineral pumice application in sewage treatment in the dairy industries was investigated, with various factors such as adsorbent dose, mixing speed, pH and contact time being studied in detail. The results obtained showed that mineral pumice in a granular form, with a contact time of 20 hours and a volume fraction of one third and pH of 8 has the ability to COD (Chemical Oxygen Demand) decreasing up to 56.9%. However, by using mineral pumice in powder form, in three cases considered, higher efficiency than for pumice granules has been observed. It seems that acidity conditions do not have a positive effect on this efficiency. As the contact time increased, the adsorption rate increased, mostly due to increased probability of collision with the adsorbent surface. With an increasing adsorbent dose, the absorption rate also increased, especially in the range of 15 g/l. Regarding the mixing speed, no definite conclusion can be drawn, because in some cases, with increasing mixing speed, the COD reduction efficiency decreased. Considering the use of mineral pumice in reducing COD, in accordance with to the obtained results, it is better to use mineral pumice in granular, rather than in powder, form.

Study the Optimization of Petroleum Refinery Wastewater Treatment by Successive Electrocoagulation and Electro-oxidation Systems

In this study, successive electrocoagulation (EC) and electro-oxidation (EO) processes were used to minimize some of the major pollutants in real wastewater, such as organics (detected by chemical oxygen demand (COD)), and turbidity. The wastewater utilized in the present study was collected from the Midland Refinery Company in Baghdad-Iraq. The performance of the successive batch EC-EO processes was studied by utilizing Graphite and Aluminum (Al) as monopolar anode electrodes and stainless steel (st.st.) as the cathode. The Taguchi experimental design approach was used to attain the best experimental conditions for COD reduction as a major response. Starting from chemical oxygen demand COD of (600 ppm), the effects of current density (C.D.) (10- 20 mA/cm2), pH (4- 10), time (2– 4 h), and NaCl concentration (1.5- 2.5 g/l) on the efficiency of COD reduction were examined. The results indicated that COD reduction increased with increasing C.D., NaCl conc., and electrolysis time and increased exponentially at pH (4). The best conditions for the treatment of this wastewater were: C.D. (20 mA/cm2), pH (4), time (4 h), and NaCl conc. (2.5 g/l). At these conditions, approximately 98.12 % of COD reduction was achieved with electrical energy consumption (ENC) of about 62.04 kWh/m3. The result of analysis of variance (ANOVA) revealed that the C.D. and pH have a higher influence on the performance of organics removal, while the time and NaCl conc. have a minor impact on COD Re%.

Evaluation of a sequential batch reactor implementing mixing and aeration by recirculation through a Venturi

This work describes the design, construction, and evaluation of a sequential discontinuous reactor with recirculation and aeration through a Herschel-type Venturi tube made of high-density polyethylene, coupled to a centrifugal pump. Four laboratory-scale prototypes were built, each with a volume of 8 L and a characteristic distance for venturi discharge. During the evaluation, temperature, pH, and dissolved oxygen were monitored. Also, the chemical oxygen demand (COD), the biological oxygen demand (BOD5), and the total suspended solids (TSS) in the clarified discharge liquid were determined. The BOD5 reduction efficiency registered values higher than 80%, while the COD reduction efficiency was around 60%. Thus, the action of microorganisms reduced the biodegradability factor, the BOD5, and contributed to the DQO through soluble microbial products. Besides, the increase of solids retention time (SRT) evidenced the increase in biomass settleability, which positively contributed to SBR operation. The results obtained support the implementation of the sequential batch reactor with mixing and aeration by recirculation through a Venturi as a technology for wastewater treatment.

Fe-zeolite catalyst for ozonation of pulp and paper wastewater for sustainable water resources

The pulp and paper industry consumes enormous quality of freshwater, leading to wastewater. It must be treated to remove pollutants, particularly residual dyestuffs, before releasing them to water bodies to avoid adverse environmental effects. The traditional wastewater treatment methods used for the pulp and paper industry are less efficient in colour and chemical oxygen demand (COD) removal. The current study is aimed at developing a novel catalyst for the catalytic ozonation of pulp and paper wastewater with better colour and COD removal for sustainable resources of clean water. The proposed catalyst is impregnated by iron on natural zeolites. Various parameters such as catalyst dose, pH, ozone dose, initial COD concentration, and reaction time are studied and optimized. The performance was evaluated by comparing the results with the single ozonation process (SOP) and catalytic ozonation process (COP). The highest COD and colour reduction efficiencies have been achieved, i.e., 71%, and 88% at a natural pH of 6.8. The proposed process achieved higher COD and colour efficiencies than the single ozonation process and catalytic ozonation process using raw zeolites. The improvement in efficiencies are 23% and 29% for SOP and 17% and 19% for COP, respectively. Hence, the results proposed the sustainability and applicability of COP to treat paper and pulp sector effluent.

Photocatalytic Degradation of Sugarcane Vinasse Using ZnO Photocatalyst: Operating Parameters, Kinetic Studies, Phytotoxicity Assessments, and Reusability.

Photocatalytic degradation performance is highly related to optimized operating parameters such as initial concentration, pH value, and catalyst dosage. In this study, the impact of various parameters on the photocatalytic degradation of anaerobically digested vinasse (AnVE) has been determined through decolourization and chemical oxygen demand (COD) reduction efficiency using zinc oxide (ZnO) photocatalyst. In this context, the application of photocatalytic degradation in treating sugarcane vinasse using ZnO is yet to be explored. The COD reduction efficiency and decolourization achieved 83.40% and 99.29%, respectively, under the conditions of 250 mg/L initial COD concentration, pH 10, and 2.0 g/L catalyst dosage. The phytotoxicity assessment was also conducted to determine the toxicity of AnVE before and after treatment using mung bean (Vigna radiata). The reduction of root length and the weight of mung bean indicated that the sugarcane vinasse contains enormous amounts of organic substances that affect the plant's growth. The toxicity reduction in the AnVE solution can be proved by UV–Vis absorption spectra. Furthermore, the catalyst recovery achieved 93% in the reusability test. However, the COD reduction efficiency and decolourization were reduced every cycle. It was due to the depletion of the active sites in the catalyst with the adsorption of organic molecules. Thus, it can be concluded that the photocatalytic degradation in the treatment of AnVE was effective in organic degradation, decolorization, toxicity reduction and can be reused after the recovery process.Graphical abstract

Biofilm characterization in removal of total chemical oxygen demand and nitrate from wastewater using draft tube spouted bed reactor.

The present paper investigates the effect of dilution rate on the removal of total chemical oxygen demand and nitrate in the draft tube spouted bed reactor and morphological characteristics of biofilms formed by microorganisms ofmixed culture on granular activated carbon (GAC). The nitrate and total chemical oxygen demand (COD) decreased from 97 to 81% and 95% to 87% respectively with increase in dilution rate from 0.6/hto 1.5/hshowing that residence time in the reactor governs the nitrate and total COD reduction efficiency. Lower dilution rates favor higher production of biomass and extracellular polymeric substances (EPS). It was observed that the nitrate and total COD reduction rate increased with time along with simultaneous increase in EPS production. Thus, the performance of a reactor in terms of dynamic and steady-state biofilm characteristics associated with nitrate and organic reduction is a strong function of dilution rate. Hence these findings indicate that a draft tube spouted bed reactor is capable of simultaneously reducing total organics and nitrogen in industrial/municipal wastewater, as this reactor possesses two distinct regions aerobic and anoxic conditions which can prevail in different parts of a reactor.

Hydrogen peroxide assisted electrocoagulation treatment of rice gain based biodigester effluent: mechanism, performance, and cost analysis

Abstract In the current scenario treatment of industrial waste water is big challenge especially waste water that contain high organic load. Hydrogen peroxide assisted electrocoagulation (EC) process provides better result to treat highly polluted wastewater as compared to EC alone. However, hydrogen peroxide is well known as a strong oxidant, which cast a potential threat to human health. To overcome this problem hydrogen peroxide has been used here for treatment of wastewater in small quantity, and that consume during the process. Therefore the harmful effect of hydrogen peroxide in human and aquatic life could be minimized. This work is an attempt to treat biodigester effluent (BDE) using H2O2 assisted EC processes with respect to chemical oxygen demand (COD) and color reductions. To perform this experiment both iron and aluminum electrodes are used as an electrode material in the presence of H2O2. In case of iron electrode the maximum COD and color reduction efficiency of 98.3 and 83.6% was achieved at the cost of 1.5 Wh/dm3 energy consumption while maximum COD and color removal efficiency of 96.8 and 77.1% with 1.7 Wh/dm3 of energy consumption was observed in the aluminum electrode based EC process. A part from this conventional biological process (i.e., activated sludge treatment, ponds, and lagoon etc.) and physiochemical treatment process (i.e., coagulation, adsorption) provided treatment efficiency of 40–80% hence hydrogen peroxide assisted EC process should a better choice to treat distillery effluent. Furthermore, hybrid EC process was also performed with iron used as anode and aluminum as cathode in the presence of H2O2. Iron electrode based peroxi-EC process provided better result at optimum operating conditions; current density of 114 A/m2, initial COD concentration of 12,000 mg/dm3, initial pH of 7.3, H2O2 concentration of 120 mg/dm3, stirring speed of 120 rpm and electrolysis time of 90 min. The cost estimated for operation is 1.56 US $/m3. Finally, sludge analysis and cost optimization are also incorporated in this article.

Enhanced wastewater nutrients removal in vertical subsurface flow constructed wetland: Effect of biochar addition and tidal flow operation

Dissolved oxygen (DO) and carbon stock in substrate medium play a vital role in the nutrient removal mechanism in a constructed wetland (CW). This study compiles the results of dynamics of DO, ammonium N (NH4+-N), nitrate (NO3–N), sulfate (SO4−2), phosphate (PO4−3), chemical oxygen demand (COD), in three setups of vertical-flow constructed wetlands (TFCWs) (SB: substrate + biochar; SBP: substrate + biochar + Colocasia esculenta plantation; SP: substrate + Colocasia esculenta (SP), operated with tidal flow cycles. Experimental analyses illustrated the continuous high DO level (2.743–5.66 mg L−1) in SB and SBP after the I and II cycle of tidal flow (72 h flooding and 24 h dry phase). COD reduction efficiencies increased from 15.75 – 61.86% to 48.55–96.80% after tidal operation among operating TFCWs. N (NH4+-N) and N (NO3–N) removal were found to be 88.16%, and 76.02%; 49.32, and 57.85%; and 40.23%, and 48.94 % in SBP, SP and SB, respectively. The theory of improved nitrification and adsorption through biochar amended substratum was proposed for TFCW systems. PO4−3 and SO4−2 removal improved from 22.63 to 80.50%, and 19.69 to 75.20%, respectively after first tidal operation in all TFCWs. The microbial inhabitation on porous biochar could promote the transformation of available P into microbial biomass and also helped by the plant uptake process while SO4−2 reduction in TFCWs could be mainly due to sulfate-reducing bacterial activity and nitrate reduction process, mainly facilitated by high DO and biochar addition in such setups. The study suggests that effluent re-circulation through tidal operation and biochar supplementation in the substratum could be an effective mechanism for the improvement of the working efficiencies of CWs operated with low energy input systems.

Treatment of Cutting Oil-in-Water Emulsion by Combining Flocculation and Fenton Oxidation

Recently, the disposal of waste oil-in-water cutting emulsion has become an urgent issue because of its extremely high chemical oxygen demand (COD). The present work focuses on treating the waste cutting emulsion generated from the Samsung Thai-Nguyen factory in Vietnam. This work used multistage methods to treat the waste cutting emulsion to meet the wastewater disposal requirement and characterize the oil recovered. The multistage methods consist of the flocculation method (stage 1) and Fenton oxidation (stage 2). The wastewater after stage 1 treatment has a COD reduction efficiency of 98.24% at the condition of pH 5, Al2(SO4)3 2 g/L, C-PAM 12 mg/L, stirring speed 50 rpm, and stirring time 15 minutes. At that condition, the COD value decreased from 147200 mg/L to 2484 mg/L. After stage 2, the COD value further decreased from 2484 mg/L to 85.4 mg/L with total COD removal efficiency increasing to 99.9% at the optimum conditions of pH 3, H2O2 : FeSO4 concentration ratio of 10 : 1, and FeSO4 concentration of 14.04 g/L. After the stage 2 treatment, the wastewater with the COD value of 85.4 mg/L and BOD5 value of 30 mg/L satisfied the Vietnam standard grade B and grade A, respectively, for industrial wastewater. The oil recovered from the treatment has a heating value of 38095 ± 8 kJ/kg, and thus, it could be reusable as fuel gas.

Sono-assisted electrocoagulation treatment of rice grain based distillery biodigester effluent: Performance and cost analysis

Electrocoagulation process coupled with sonication is a type of advance oxidation process (AOP) to treat different type of waste waters. Biodigester effluent (BDE) generated from distillery industry contains very high chemical oxygen demand (COD=5500 mg/dm3) with high color (510 PCU) appearance. Organics reduction of biodigester effluent (BDE) in term of chemical oxygen demand (COD) and color have been investigated in a batch sono-electrocoagulation reactor with different electrode combinations such as Fe-Fe, Al-Al, Fe-Al, and Al-Fe at ultrasound frequency of 40 kHz. The impact of different operating parameters such as electrolyte concentration, electrode combination, pH and current density (CD) on COD and color removal are evaluated. The electrode combination of Fe-Fe has provided better results in sono-electrocoagulation process as compared to sonication and electrocoagulation alone. The maximum COD and color reduction efficiency of 99.1 % and 61.6 % was found at the electrode combination of Fe/Fe, CD 69.44 A/m2, pH 8, NaCl concentration 5 mg/dm3, and process time of 125 min. On the other hand the maximum COD and color removal efficiency of 98.3 % and 58.1 % was observed with the electrode combination of Al-Al at same operating conditions as described for Fe. Finally, sludge analysis and cost optimization are also incorporated in this article. It is found that at optimum condition (electrode combination of Fe/Fe, CD 69.44 A/m2, pH 8, NaCl concentration 5 mg/dm3, and process time of 125 min) the operating cost of the process is 1.39 $/m3. Sludge obtained after the treatment process contains anodic material (0.07 kg iron for the treatment 1 m3 of BDE) and also sludge had good heating value (5.5 MJ/kg). This work demonstrated that sono-electrocoagulation process is well applicable to treat BDE.

Optimization of mixing ratio, shaking speed, contact time, and pH on reduction of Chemical Oxygen Demand (COD) and Ammoniacal Nitrogen (NH3-N) in leachate treatment

ABSTRACT When the inevitable generation of waste is considered as hazardous to health, damaging ecosystem to our environment, it is important to develop an innovative technologies to remediate pollutant sources for the safety and environmental protection. The development of adsorption technique for the reduction of extremely effective pollutants in this regard. Green mussel and zeolite mixing media were investigated for the reduction of the concentration of organic constituents (COD) and ammoniacal nitrogen from leachate. The leachate treatability was analyzed under various stages of treatment parameter, namely mixing ratio, shaking speed, contact time, and pH. Both adsorbent were sieve values in between 2.00–3.35 mm particle size. The optimum pH, shaking speed, contact time, and mixing ratio were determined. Leachate samples were collected from influent untreated detention pond at Simpang Renggam landfill site in Johor, Malaysia. The result of leachate characterization properties revealed that non-biodegradability leachate with higher concentrations of COD (1829 mg/L), ammoniacal nitrogen (406.68 mg/L) and biodegradability value (0.08) respectively. The optimal reduction condition of COD and ammoniacal nitrogen was obtained at 200 rpm shaken speed, 120 minute shaken time, optimum green mussel and zeolite mix ratio was 2.0:2.0, and pH 7. The isothermic study of adsorption shows that Langmuir is best suited for experimental results in terms of Freundlich model. The mixing media also provided promising results to treating leachate. This would be greatly applicable in conventionally minimizing zeolite use and thereby lowering the operating cost of leachate treatment. Implications: The concentration of organic constituents (COD) and ammoniacal nitrogen in stabilized landfill leachate have significant strong influences of human health and environmental. The combination of mixing media green mussel and zeolite adsorbent COD and ammoniacal nitrogen reduction efficiency from leachate. This would be greatly applicable in future research era as well as conventionally minimizing high cost materials like zeolite use and thereby lowering the operating cost of leachate treatment.

Water recovery from textile bath wastewater using combined subcritical water oxidation and nanofiltration

Abstract In this study, textile dye bath wastewater was treated by subcritical water oxidation (SCWO) and pressure-driven membrane process. 54.5% of chemical oxygen demand (COD) reduction and 91.7% of color removal were obtained using eco-friendly SCWO method in the presence of H2O2. Box-Behnken design was performed to optimize the SCWO process and precision of the models were evaluated by ANOVA. Two different nanofiltration (NF270 and NF90) membranes were tested before and after SCWO pretreatment. The effect of membrane type (NF270 and NF90) and transmembrane pressure (10, 20, 30, 40 bar) were studied to improve COD reduction and colour removal efficiency. The results showed that steady-state permeate flux increased from 6.6 to 23.5 L/m2.h for NF270 at 30 bar and from 10.0 to 12.4 L/m2.h for NF90 membrane at 40 bar when SCWO was applied as the pretreatment method. The results depicted that SCWO pre-treatment increased the permeate flux almost 2–3 fold. COD was also tested for all permeates and the highest COD reduction efficiency was obtained for SCWO + NF90 combined process. The highest COD reduction and color removal efficiencies were obtained as 96.1% and 99.3%, respectively, for combined SCWO + NF90 process at 40 bar. The proposed combined SCWO + NF90 process was successfully used to recover wastewater from textile dye bath wastewater.

Fungal treatment of mature landfill leachate utilizing woodchips and wheat-straw as co-substrates.

Mature landfill leachate (MLL) tend to be highly contaminated due to the presence of refractory contaminants such as humic-fulvic substances, xenobiotic compounds, and heavy metals. This study investigated the treatment efficiency of MLL by deploying Cladosporium sp., Trichoderma asperellum, and Tyromyces chioneus fungal strains. Chemical oxygen demand (COD) and soluble COD (sCOD) removal efficiencies were assessed along with the evaluation of lignocellulosic enzymatic activities of laccase (Lac), lignin-peroxidase (LiP), and manganese-peroxidase (MnP). Glucose, woodchips, and wheat straw were utilized as co-substrates. Higher percentage of COD and sCOD reduction efficiencies and lignocellulosic enzymatic activities were found for woodchips than glucose and wheat-straw. The highest sCOD removal rates were 44%, 38% and 59% by Cladosporium sp., T. asperellum, and T. chioneus, respectively. Overall, Lac activity was significantly higher than LiP and MnP activity for all three species. Tyromyces chioneus was the most effective strain among the three selected fungi in terms of COD and sCOD reduction efficiencies and high enzymatic activities of 165, 14 and 20 U/L were detected for Lac, LiP, and MnP, respectively. Tyromyces chioneus is a potentially effective fungal strain for the enhanced bioremediation of MLL and its further investigation is recommended to explore the removal of recalcitrant contaminants from problematic wastewater.

Phytoremediation capabilities of Salvinia molesta, water hyacinth, water lettuce, and duckweed to reduce phosphorus in rice mill wastewater

The objective of this study was to investigate the reduction of phosphorus from rice mill wastewater by using free floating aquatic plants. Four free floating aquatic plants were used for this study, namely water hyacinth, water lettuce, salvinia, and duckweed. The aquatic plants reduced the total phosphorus (TP) content up to 80% and chemical oxygen demand (COD) up to 75% within 15 days. The maximum efficiency of TP and COD reduction was observed with water lettuce followed by water hyacinth, duckweed, and salvinia. The study also aims to predict phosphorus removal by three modeling techniques, for example, linear regression (LR), artificial neural network (ANN), and M5P. Prediction has been done considering hydraulic retention time (HRT), hydraulic loading rate (HLR), and initial concentration of phosphorus (Cin) as input variables whereas the reduction rate of TP (R) has been considered as a predicted variable. ANN shows promising results as compared to M5P tree and LR modeling. The model accuracy is analyzed using three statistical evaluation parameters which are coefficient of determination (R2), root mean square error (RMSE), and means absolute error (MAE).