Solids Removal Efficiency Research Articles

Life cycle assessment for algae-based desalination system

To clearly understand the environmental impacts of algae-based desalination system, a life cycle assessment is undertaken by comparing four different scenarios: (1) multi-stage microalgae based desalination system without algal biomass reuse; (2) multi-stage microalgae based desalination system with algal biomass reuse; (3) hybrid desalination system with microalgae as the pre-treatment for Low Pressure Reverse Osmosis; and (4) conventional Seawater Reverse Osmosis system. It is suggested that scenarios 2 and 4 have the overall lowest and highest environmental impacts, respectively. This phenomenon is probably caused by the lower energy consumption and lower operational and maintenance requirements of high rate algal pond system. Furthermore, scenario 2 considers the algal biomass reuse to generate electricity through anaerobic digestion, which could offset the environmental impacts. It is also identified that the operational phase contributes approximately 50–60% of the total environmental impact in most impact categories for algae-based desalination system, however, the operational phase contributes around 70–80% of the total environmental impact for membrane based desalination system. A sensitivity study is undertaken to evaluate the effects of three key design parameters on environmental impact in global warming impact category. It is identified that the total dissolved solids removal efficiency of high rate algal pond plays the most important role in determining the potential environmental impacts of different scenarios. This study clearly shows that scenario 2 of multi-stage microalgae based desalination system with algal biomass reuse is the most environmentally friendly desalination approach.

Performance application of ultraviolet disinfection technique for raw water

Microbial water disinfection with UV rays is a universal technology. Disinfection is a method used to treat drinking water. This can be accomplished using physical and/or chemical processes. Physical Methods: Heating and UV rays are two main methods - UV rays to destroy cells and kill bacteria. The physical process generally gives drinking water an instant purification without producing harmful substances. However, there is no pollution in the water to ensure continuous cleaning. This study’s primary goal is to obtain environmentally safe drinking water in situations of water shortages and homes that lack clean water. Therefore, resort to appropriate home treatment. Therefore, an experimental laboratory has been established to test the ceramic filter’s efficiency in removing turbidity and plankton and everything that would change the properties of drinking water. Thus, several stages in water purification are shortened, as in the case of water treatment plants. To determine the efficiency of UV sterilization in killing bacteria, especially fecal coliform bacteria and E-coli bacteria. Work has taken place by taking samples of river water near Al Wahda water treatment plant. This technique works on water according to special criteria before entering the sterilizer. A commercially available ceramic filter was used for this. The ceramic filter is excellent at reducing turbidity with removal efficiency (96 ∼ 97%), suspended solids removal efficiency (99 ∼ 100%), iron removal efficiency (100%), bacteria removal efficiency (45 ∼ 50 %) which is good removal rate because it is a commercial filter. The efficiency of the UV sterilizer in killing bacteria reached (100%). This technique is very excellent as it does not produce secondary substances and does not change color, taste, or smell.

PFAS removal from wastewater by in-situ formed ferric nanoparticles: Solid phase loading and removal efficiency

PFAS removal by in-situ formed ferric nanoparticles via ozonation was evaluated in this study. The tests were conducted with synthetic contaminated water prepared from the firefighting foam concentrate at PFAS concentrations of 8.33–133 µg/L, pHs of 3–7.5, and ozone bubbling times of 15–45 s. It was found the particle sizes of the in-situ formed ferric nanoparticles were affected by ferrous dose, pH value, and ozone bubbling time. The highest PFAS removal achieved was 44%, when the PFAS feed concentration was 8.33 µg/L, ferrous dose was 40 µg/L, feed pH value was 6.2 and ozone bubbling time was 45 s. The PFAS solid phase loading of the ferric nanoparticles was significantly higher than conventionally used adsorbents. The highest PFAS solid phase loading achieved was 80% when the PFAS concentration was 8.33 µg/L, pH was 3, and mass ratio of ferrous sulphate to PFAS was 1:1.7 ± 0.3. It was found that the specific area of the nanoparticles was directly related to PFAS removal and solid phase loading. It was also found that the highest PFAS and highest PFAS solid phase loading of ferric nanoparticles could not be achieved simultaneously under the tested experimental conditions.

Optimization of continuous electrocoagulation-adsorption combined process for the treatment of a textile effluent

Experimental setup: (a): Real schematic of pilot, (b): 3D scheme of pilot/ 1: tank with untreated effluent, 2: variable frequency pump, 3: Electrocoagulation reactor, 4: adsorption reactor, 5: mechanical stirrer, 6: tank for sedimentation, 7: acrylic container of the suspension of clay, 8: mechanical mixer of the suspension of clay, 9: 12 Volt peristaltic pump, 10: control panel of current supplier, 11: 10 parallel iron electrodes. • The full continuous combined process based on electrocoagulaion-adsorption on crude clay is a very efficient process for textile effluent decontamination. • The achieved removal efficiencies of color, COD and TSS were respectively 96.87%, 89.77% and 84.46%. • The achieved treated effluent fulfill the Tunisian standards of rejected wastewater and could be used in preparation process or in irrigation. • Treatment efficiencies were enhanced at neutral pH range, slow effluent flow rate, high voltage and high adsorbent suspension flow rate. The aims of this study is to design and optimize the functioning of a full continuous combined process based on electrocoagulaion-adsorption on crude Tunisian clay to treat a real textile effluent. The clay characterization shows that the used clay is a rich-smectite clay. The response surface methodology (RSM) technique based on Box-Behnken design (BBD) was used to optimize the process. At optimum conditions which are initial pH solution of 8.24, effluent flow rate of 0.5 L·min −1 , voltage of 70 V, and added suspension of clay flow rate of 100 ml·min −1 the achieved color, chemical oxygen demand (COD) and total suspended solid (TSS) removal efficiencies were respectively 96.87%, 89.77% and 84.46% with 0.75USD·m −3 as total cost. The additional laboratory experiments at optimum conditions agree with the predicted results, which confirm the accuracy and the capability of RSM to predict results in the defined space. Finally the designed process could be a good eco-friendly alternative to treat and reuse wastewater in industrial process with reasonable cost.

Impact of nickel nanoparticles on biogas production from cattle manure

The presence of nano-nutrients can be stimulatory for the anaerobic digestion (AD) of hardly degradable wastes and thus enhance process performance. One of the essential trace elements, nickel (Ni), is involved in multiple important enzymes necessary for efficient AD. This study investigated the effects of Ni nanoparticles (NPs) with different concentrations on cattle manure AD performance and effluent chemical composition. The results showed that the highest specific biogas production was attained with 4 mg/L Ni NPs (p<0.05) and was 792.00 mL/g VS compared with cattle manure-only which yielded only 589.20 mL/g VS. Moreover, the addition of 2 mg/L Ni NPs significantly increases the methane yield (p<0.05) by 70.46% compared with cattle manure-only. Besides, H2S production decreased by 16.50%, 90.47%, and 51.89% compared with cattle manure-only when the cattle manure was treated by 1, 2, and 4 mg/L Ni NPs, respectively. The supplementation of bio-digester with 2 mg/L Ni NPs improved the total and volatile solids removal efficiencies by 19.2% and 12.1% and maintained pH at a suitable level (6.8–7.3). FTIR spectrum of effluent presented the addition of Ni NPs changed the intensity and shift of peaks compared with cattle manure-only peak. Moreover, all of the effluent samples from the AD systems using Ni NPs showed stronger fertilizer values, as well as the effluent with 2 mg/L Ni NPs, had the highest sulfide content (31.2%, increase), leading to higher H2S removal efficiency by 47.5%. A first-order kinetic model showed an increase up to 1.88-fold in the hydrolysis rate constant (K), in 4mg/L Ni NPs compared to cattle manure-only, leading to higher biogas yield.

Effect of organic loading rate on the anaerobic digestion of swine waste with biochar addition.

The aim of this study was to investigate the impact of biochar addition on the mesophilic semi-continuous anaerobic digestion of swine waste with a focus on the effects of the organic loading rate (OLR) on biogas production, methane yield, total volatile fatty acids (TVFA), alkalinity, ammonium, volatile solids (VS) removal efficiency and process stability. Four reactors, two with amended biochar (R1 and R2) and two without biochar addition as controls (R3 and R4), were operated at OLRs in the range of 2-7 g VS/(L d), which corresponded to hydraulic retention times (HRTs) in the range of 7-2 days, respectively. The addition of biochar initially caused an increase in the generation of biogas and methane when compared to the control reactors when the process operated at OLRs of 2 and 3 g VS/(L d). This behaviour could be attributed to the presence of several trace elements (such as Fe, Co, Ni and Mn) in the biochar, which are involved in the action of acetyl-CoA synthase and methyl coenzyme M reductase to catalyse key metabolic steps, especially the methanogenic stage. The pH, alkalinity, TVFA and TVFA/Alkalinity ratio values for the effluents remained within the optimal ranges for the anaerobic digestion process. It was also found that the increase in OLR in the range of 2-5 g VS/(L d) determined a proportional increase in the VS removal rate. However, when the OLR increased up to 7 g VS/(L d), a drastic decrease in the VS removal rate was found for the control reactors. Biochar amendment contributed to a more balanced state of the anaerobic process, preventing biomass washout.

Single-Stage and Two-Stage Anaerobic Digestion of Food Waste: Effect of the Organic Loading Rate on the Methane Production and Volatile Fatty Acids

The high organic content of food waste (FW), which represents the largest proportion of municipal solid waste (MSW) (in Latinamerican countries 50–75%), makes its treatment increasingly common trough technologies such as anaerobic digestion (AD), to obtain value-added by-products, such as renewable energy in the form of methane, digestates and other by-products of biotechnological applications such as long-chain fatty acids. In this study, the influence of semi-continuous reactors in single-stage (R1) and two-stage (R2: acidogenic and R3: methanogenic reactors) configurations on the AD-FW was evaluated (including parameters related to process monitoring, organic matter conversion and process reactions) with the following organic loading rate (OLR: kgVS m-3 d-1) values: i. R1: 0.7, 1.5, 3.0 and 6.0; ii. R2: 3.0, 4.0, 9.0 and 15.0; and R3: 1.0, 2.0, 4.0 and 7.0. The two-stage configuration showed a better performance in terms of: i. the OLRs: 35% higher than that in the single-stage configuration, with chemical oxygen demand (CODtotal) and volatile solid (VS) removal efficiencies > 80%; ii. the best performance in terms of methane production, with statistically significant differences (p<0.05) in the quantity and quality of biogas and iii. obtaining other by-products with high added value, such as behenic and caproic acid, which are useful in biotechnological applications. Additionally, it was found that total reducing sugars (TRS) are an important parameter in the monitoring and conversion of matter organic, mainly in two-stage configuration.

Life-cycle cost analysis of a hybrid algae-based biological desalination – low pressure reverse osmosis system

To fully understand the economic viability and implementation strategy of the emerging algae-based desalination technology, this study investigates the economic aspects of algae-based desalination system by comparing the life-cycle costs of three different scenarios: (1) a multi-stage microalgae based desalination system; (2) a hybrid desalination system based on the combination of microalgae and low pressure reverse osmosis (LPRO) system; and (3) a seawater reverse osmosis (SWRO) desalination system. It is identified that the capital expenditure (CAPEX) and operational expenditure (OPEX) of scenario 1 are significantly higher than those of scenarios 2 and 3, when algal biomass reuse is not taken into consideration. If the revenues obtained from the algal biomass reuse are taken into account, the OPEX of scenario 1 will decrease significantly, and scenarios 2 and 3 will have the highest and lowest OPEX, respectively. However, due to the high CAPEX of scenario 1, the total expenditure (TOTEX) of scenario 1 is still 27% and 33% higher than those of scenarios 2 and 3, respectively. A sensitivity study is undertaken to understand the effects of six key parameters on water total cost for different scenarios. It is suggested that the electricity unit price plays the most important role in determining the water total cost for different scenarios. An uncertainty analysis is also conducted to investigate the effects and limitations of the key assumptions made in this study. It is suggested that the assumption of total dissolved solids (TDS) removal efficiency of microalgae results in a high uncertainty of life-cycle cost analysis (LCCA). Additionally, it is estimated that 1.58 megaton and 0.30 megaton CO2 can be captured by the algae-based desalination process for scenarios 1 and 2, respectively, over 20 years service period, which could result in approximately AU $18 million and AU $3 million indirect financial benefits for scenarios 1 and 2, respectively. When algal biomass reuse, CO2 bio-fixation and land availability are all taken into account, scenario 2 with hybrid desalination system is considered as the most economical and environmentally friendly option.

Use of natural coagulants (Moringa oleifera and Benincasa hispida) for volume reduction of waste drilling slurries

Drilling Slurry or drilling mud is used to stabilize the drilled wellbores. Unfortunately, its disposal on land renders the soil infertile, while its coagulation with aluminium salts poses potential health risks. Here, two natural coagulants: Moringa oleifera and Benincasa hispida were investigated as potential sustainable alternatives to chemical coagulants. These are cost-effective, highly biodegradable, and safe from the human health point of view. Various forms of these substance: seed powder, de-oiled seed powder, and seed oil were used to minimize the drilling mud slurries. For the turbidity removal, the best efficiency of 99.71% was obtained by using de-oiled seed powder of Benincasa hispida whereas the total solids removal efficiency of 94.19% was obtained by using de-oiled seed powder of Moringa oleifera at an optimum dosage of 10 g/l. These results are comparable to those obtained by using alum, thus confirming the effectiveness of the natural coagulants for management of drilling slurries.

Study on Optimization of Tungsten Ore Flotation Wastewater Treatment by Response Surface Method (RSM)

A large amount of collectors, inhibitors and modifiers such as oleic acid, water glass and sodium carbonate are added to the flotation processing of tungsten ore, resulting in the difficulty of the suspended solids (SS) with the residual water glass settling down in the flotation wastewater. The removal efficiency of the suspended solids is low with commonly used reagents like polyaluminium chloride (PAC) and polyacrylamide (PAM). This paper innovatively applied calcium chloride (CaCl2) to treat flotation wastewater and optimized the dosage of CaCl2, PAM and the pH value. The experimental results showed that when the dosage of 595 mg/L CaCl2 was combined with 21 mg/L PAM at pH 12, the turbidity removal ratio could reach 99.98%, and the residual turbidity of the supernatant was 0.23 NTU. The effluent could fully meet the requirements for reuse in industrial, urban miscellaneous and scenic environment water consumption (turbidity &lt; 5 NTU). The quadratic equation model fitted with Design-Expert 8.0.6 software was constructed as Y = 91.52 + 8.68A + 1.11B − 1.02C − 1.7AB + 0.86AC + 0.06BC − 1.56A2 + 2.09B2 − 1.89C2, which had a good accuracy of the predicted responses versus the experimental data.

Anaerobic co-digestion of rice straw and de-oiled rice bran for biomethane production

The main aim of anaerobic co-digestion of rice straw is to enhance volumetric methane yields and process stability to achieve synergetic effects. However, high carbon to nitrogen ratio of rice straw causes poor process stability for mono-digestion. This study investigated the co-digestion of rice straw and de-oiled rice bran, a nitrogen-rich by-product of the rice milling industry. The spent bio-slurry (having total solids concentration of 2.19%) from running de-oiled rice bran which inherently contains various types of microbes was used as an inoculum for process start-up. A series of experiments were conducted to optimise the methane yield in semi-continuous anaerobic digester operating at 30 days of hydraulic retention time at mesophilic temperature conditions. Co-digestion studies of rice straw and de-oiled rice bran with three different mixing ratios were conducted by maintaining a specific total solids concentration of 5.0, 7.5, and 10.0% total solids concentration for the designated digester. The biogas production, methane contents, volatile matter degradation efficiency were determined to evaluate the stability and performance of the system. The digester maintained at 5% and 7.5% TS showed nearly similar results in terms of methane yield and volatile matter conversion efficiency. During the entire experimentation the percentage of methane content in the produced biogas was in the range of 24.8–55.4%. The average methane yield of 0.169 and 0.173 L/g-VS was found for digester maintained at 5.0% and 7.5% TS respectively. However, the volatile solid mass removal efficiency of 40.13% and 37.94% was recorded for the digester maintained at 5% and 7.5% TS respectively. Since no chemical or thermal pre-treatment was adopted during the entire process it is highly economical and adaptable for concerned industries. Ultimately, the results of the present study were compared to the previous studies on anaerobic co-digestion of RS, which shows the promising result with no extra added input cost.

Electrochemical mineralization of abattoir wastewater with continuous system

This study aims to determine the effects of initial pollutant concentration level (1/1–1/4), flow rate (10–40 mL/min), NaCl concentration (0.1–1 M), pH (3–9) and current density (4.73–23.67 mA/cm2) parameters on the removals of total suspended solids, total organic carbon, chemical oxygen demand, total nitrogen and color for economic treatment of cattle-abattoir wastewater using mesh-type Ti/Pt anodes with continuous EO system. Total suspended solids, total organic carbon, chemical oxygen demand, total nitrogen and color analyses were carried out according to photometric method, catalytic oxidation method, closed reflux colorimetric method, nitrogen cell test method and platinum–cobalt method, respectively. The effluent chloride levels were analyzed according to the argentometric titration method. According to results, all operational parameters had an impact on removal efficiencies but the most effective parameters on energy consumption were NaCl concentration and applied current density. Although two possible system conditions were determined according to removal efficiencies the operating conditions with the lowest energy consumption are considered to be optimal. The optimum operating conditions were determined as NaCl concentration of 1 M, CD of 4.73 mA/cm2, initial pH of 7.03, reaction temperature of 25 °C and FR of 10 mL/min. Under these conditions removal efficiencies (%) for total suspended solids, total organic carbon, chemical oxygen demand, total nitrogen and color were found as; 98.28, 93.03, 97.44, 95.53 and 99.80, respectively. The energy consumption values were calculated as 2.42 kWh/kg COD and 19.43 kWh/m3. The approximate cost to treat 1 m3 wastewater was calculated as $ 6.43. The kinetic behavior abided by a pseudo-first-order model.

Efficiency of suspended solid removal from tofu production using Rotating Biological Contractor (RBC)

Tofu is a common food in Indonesia, made from soybean, and needs gigantic water for the process. The liquid waste of the tofu industry is usually directly discharged into the river without being processed. Liquid wastes of tofu have high organic content and become a problem in water pollution. Rotating Biological Contactor (RBC) is efficient method to treat waste with a high organic matter load by utilizing microorganisms to consume organic matter through biofilms. Biofilm will degrade organic matter aerobically. The purpose of the study is to determine the capability of RBC to reduce the organic content of tofu wastewater with different rotations of the disk. Rotation was experimentally varied from 30, 40, 50, 60 RPM and control. Results were considered in percentage decrease from the untreated waste: TSS of 87.56 ± 6.48%, BOD of 99.13 ± 0.21 %, and COD of 98.53 ± 0.08%. To conclude, the optimum rotation is 50 RPM for decreasing BOD and COD, otherwise 40 RPM for reducing TSS. The results effluent RBC on three parameters passed the quality standards legally for the soybean processing company or activity.

Characterization of pistachio processing industry wastewater and investigation of chemical pretreatment

This study was carried out in two stages; in the first stage of the study, wastewater characterization of wastewater originating from the pistachio industry was primarily completed, and in the second stage, chemical pre-treatment studies were completed. Pistachio wastewater used in the study was obtained from a pistachio processing factory located in Gaziantep province. In chemical treatment studies, montmorillonite clay, AlCl3, Al2(SO4)3, Fe2(SO4)3 and FeCl3 were used as coagulants. As a result of chemical treatability tests, AlCl3 was determined to be the best coagulant. With AlCl3 at optimum dosage and optimum pH value, 99.6% suspended solid (SS) removal efficiency, 65.8% chemical oxygen demand (COD) removal efficiency and 85.5% total phenol (TP) removal efficiency were obtained.

The impact of seasonal variations about temperature and photoperiod on the treatment of municipal wastewater by algae-bacteria system in lab-scale

The co-cultivation of microalgae and bacteria has become an attractive approach for treating wastewater. This approach can achieve both cost-effective nutrient removal and biomass resource recovery. However, the development of full-scale algae-bacteria systems or enhanced pond systems has been limited, because of the complexity and changeability of environmental factors in this process. This study investigated the effects of seasonal variations about temperature and photoperiod on municipal wastewater treatment by algae-bacteria system in lab-scale. Nutrient removal, biomass growth, settling ability, and community structures were examined using cultures of Chlorella vulgaris, Scenedesmus obliquus, Spirulina platensis, and aerobic activated sludge in raw municipal wastewater. Results showed that the nutrient removal and biomass yield varied with seasonal conditions. High removal rates and biomass production percentages were achieved in summer and autumn conditions with aeration. The highest specific growth rate was 0.46 d−1; the highest total nitrogen removal rate was 2.34 d−1; and the highest total suspended solids removal efficiency was 96.3 ± 2.1% in summer conditions with aeration. The highest total phosphorus removal rate was 1.67 d−1 in the autumn season with aeration. An overall analysis indicated that Chlorella vulgaris and Scenedesmus obliquus, combined with bacteria (Proteobacteria, Firmicutes, Bacteroidetes, Chloroflexi) can effectively use different carbon, nitrogen, and phosphorus sources from wastewater in summer and autumn conditions. Further research should focus on methods for effectively and inexpensively improving nutrient removal and recovering biomass at low temperatures and with short photoperiods.

Valorization of sugarcane bagasse waste for fly ash production and application as an adsorbent

In this study, fly ash (FA) was derived from extracted sugarcane bagasse solid waste (ESBSW) and chemically modified to apply as an adsorbent. Impact of activated FA particles (200 and 250 µm) and adsorbent bed height (4, 6 and 8 mm) on pollutant removal efficiency was evaluated. ESBSW was combusted in laboratory-scale gasifier operated at 1000 °C for 1 h. The black solid residue was sieved to obtain the desired particle size followed by activation with 10% and 15% sulfuric acid. Wastewater samples collected from the drainage site of BUITEMS were analyzed and treated with the prepared adsorbent. ESBSW-FA 250 activated with 15% H 2 SO 4 with 8 mm bed height showed high efficiency. Where, 94.37%, 95.1% and 63.5% removal efficiency of chemical oxygen demand (COD), total solids (TS) and turbidity was attained, respectively. The pH of treated water was neutral. ESBSW has shown great potential to be used as a precursor for valuable byproducts. It's recycling for adsorbent preparation will economically and environmentally benefit the sugar industry.

Valorization of sugarcane bagasse waste for fly ash production and application as an adsorbent

In this study, fly ash (FA) was derived from extracted sugarcane bagasse solid waste (ESBSW) and chemically modified to apply as an adsorbent. Impact of activated FA particles (200 and 250 µm) and adsorbent bed height (4, 6 and 8 mm) on pollutant removal efficiency was evaluated. ESBSW was combusted in laboratory-scale gasifier operated at 1000 °C for 1 h. The black solid residue was sieved to obtain the desired particle size followed by activation with 10% and 15% sulfuric acid. Wastewater samples collected from the drainage site of BUITEMS were analyzed and treated with the prepared adsorbent. ESBSW-FA 250 activated with 15% H2SO4 with 8 mm bed height showed high efficiency. Where, 94.37%, 95.1% and 63.5% removal efficiency of chemical oxygen demand (COD), total solids (TS) and turbidity was attained, respectively. The pH of treated water was neutral. ESBSW has shown great potential to be used as a precursor for valuable byproducts. It's recycling for adsorbent preparation will economically and environmentally benefit the sugar industry.

Valorization of sugarcane bagasse waste for fly ash production and application as an adsorbent

In this study, fly ash (FA) was derived from extracted sugarcane bagasse solid waste (ESBSW) and chemically modified to apply as an adsorbent. Impact of activated FA particles (200 and 250 µm) and adsorbent bed height (4, 6 and 8 mm) on pollutant removal efficiency was evaluated. ESBSW was combusted in laboratory-scale gasifier operated at 1000 °C for 1 h. The black solid residue was sieved to obtain the desired particle size followed by activation with 10% and 15% sulfuric acid. Wastewater samples collected from the drainage site of BUITEMS were analyzed and treated with the prepared adsorbent. ESBSW-FA 250 activated with 15% H 2 SO 4 with 8 mm bed height showed high efficiency. Where, 94.37%, 95.1% and 63.5% removal efficiency of chemical oxygen demand (COD), total solids (TS) and turbidity was attained, respectively. The pH of treated water was neutral. ESBSW has shown great potential to be used as a precursor for valuable byproducts. It's recycling for adsorbent preparation will economically and environmentally benefit the sugar industry.

Green sustainable technology for biotreatment of actual dairy wastewater in constructed wetland

AbstractBACKGROUNDDue to the environmental problems caused by food processing wastewaters and their complex and expensive treatment methods, it becomes mandatory to seek a sound, sustainable and environmentally friendly solution such as constructed wetland (CW). This study aimed to investigate the potential of treating real dairy wastewater in CW. Six horizontal subsurface flow CW microcosms were set up using different conventional and cost‐effective supporting media, which were gravel, soil and sand. All the CWs were fueled continuously with real fresh dairy wastewater. Five of the six CW microcosms were planted with Canna indica. The remaining CW microcosm was kept unplanted and was considered as a control microcosm.RESULTSThe results revealed significant removal efficiencies of organic matter (as chemical oxygen demand) up to 89.92%, 97.6%, 95.8%, 97.2%, 97.3% and 98.2%, for CW1, CW2, CW3, CW4, CW5 and CW6, respectively. Also, high removal efficiencies of ammonium were observed in the range of 98.4–82.0%, whereas removal efficiencies of total suspended solids were in the range of 99.2–93.4%.CONCLUSIONThe results demonstrated that the dominant mechanisms for organics and ammonium removal were biodegradation processes. These promising results confirmed the validity of using constructed wetland as a sustainable cost‐effective approach for dairy wastewater treatment. © 2020 Society of Chemical Industry

Co-pretreatment of Municipal Wastewater and Landfill Leachate by Chemical Coagulation Using Ferric Chloride and Aluminum Sulfate

In this study, co-pretreatment of municipal wastewater (MW) and landfill leachate (LL) was investigated by means of coagulation using ferric chloride and aluminum sulfate. The effects of operating conditions on process performance were examined, which included pH, coagulant type and coagulant dose. For both coagulants, the best removal efficiency was achieved at the initial pH of 5. At this pH, the removal efficiencies of chemical oxygen demand (COD), suspended solids (SS) and turbidity were 82%, %99 and %99, respectively with ferric chloride and 72%, 98% and 98.5%, respectively with aluminum sulfate. For the ratios ranging between 10:1 and 5:1 of MW to LL, the optimum dose was determined as 500 mg/L for both coagulants. When the ratio of MW to LL was reduced from 5:1 to 1:1, the coagulant dose required was raised from 500 to 1000 mg/L and the removal efficiency of pollutants reduced. Better removal efficiencies were achieved by ferric chloride in comparison to aluminum sulfate. The results revealed that coagulation could be applied as pretreatment for co-treatment of MW and LL.