Chemical Removal Research Articles

Chemical oxygen demand removal by modified carbon with H2SO4 from oil palm fruit bunches

ABSTRACT The utilisation of biomass to be used as a promising material is essential to reduce environmental pollution. This study aims to determine the effect of adding a modifier to activated carbon from oil palm empty bunches. The material’s efficacy in reducing Chemical Oxygen Demand (COD) in the water environment was also conducted. In this research, the removal of COD was investigated using activated carbon from empty fruit bunches as a adsorbent with modification. The carbon synthesis of activated carbon was done by synthesising oil palm empty fruit bunches at 500 °C with activation using H3PO4 and surface modification with H2SO4. Modifying the activated carbon surface is expected to increase pores and clean the surface to optimise adsorption The activated and modified carbon were characterised using FTIR, SEM, XRD, and BET methods. The FTIR results show the absorption of functional groups indicating the presence of functional groups for C-H, O-H, C-O, C=C and C=O. The Boehm Titration method showed that total acid increased after modification. SEM analysis on samples shows that the sample surface is porous, and the number of pores produced is increasing. The XRD analysis result shows that the material revealed two broad diffractions at degree 2θ corresponding to the faces of porous carbon. The BET result showed that the material had a higher pore volume after the modification of activated carbon. The adsorption of modified carbon was higher than that of activated carbon. The optimum contact time for activated and modified activated carbon is 90 minutes and pH 2. The modified carbon from oil palm fruit bunches can reduce COD in a water environment.

A novel biochar composite derived from oil-based drill sludge and cuttings: Structural characterization and electrochemical properties

How to dispose of large quantities of hazardous shale gas drilling waste is an important worldwide problem facing the oil and gas industry. In this study, we report an environmentally friendly and low energy consumption approach (carbonization followed by activation) to convert oil-based drill sludge (OBDS) and oil-based drill cuttings (OBDCs) into biochar composites and investigate the effect of hydrofluoric acid (HF) acidification on them. The biochar composites were prepared using the OBDS, OBDCs, the mixtures of OBDS and OBDCs, and HF treatment the mixtures were named OS, OC, OSC, and OSC-HF, respectively. The characterization result of synthesized biochar composites indicated that the OSC had a larger specific surface area and a higher degree of graphitization. The composites mainly consisted of SiO2 and BaSO4, except for biochar. The OSC electrode exhibited the highest oxygen evolution potential (1.72 V vs Ag/AgCl) and the lowest charge transfer resistance compared with OS, OC, and OSC-HF electrodes, implying that SiO2 plays an important role in electrochemical performance. Using the OSC electrode as an anode, the chemical oxygen demand removal efficiency of the OBDS supernatant was 79.4 ± 0.95%. Further, the OSC electrode could maintain higher degradation efficiency and stability after the fifth reuse. The study provides a promising route for the proper disposal and resource utilization of OBDS and OBDCs and proposes a novel biochar compound as an electrode for the efficient treatment of wastewater. Moreover, this work highlights the important significance of the simultaneous resource utilization of waste and the treatment of wastewater using waste materials.

Meandering Flow Filter for Phosphorus Removal as a Component of Small Wastewater Treatment Plants—A Case Study

Chemical phosphorus removal in wastewater treatment plants can be carried out by precipitation with iron or aluminum salts or by filtering wastewater through a bed of active sorptive material. This work aimed to investigate whether using a meander flow filter filled with the sorption material Rockfos® would improve phosphorus removal efficiency in a selected wastewater treatment plant. Tests were performed under laboratory conditions using a model of a meander flow filter and a similar filter under field conditions at full technical scale. This filter was the final element of a hybrid constructed wetland located in the village of Białka in the municipality of Dębowa Kłoda in southeastern Poland. A laboratory model of a phosphorus removal filter with vertical incomplete baffles forcing a meandering water flow was constructed to determine the hydraulic conditions of the flow. After one year of operation, the filter with horizontal wastewater flow operating at its full technical scale (without meanders) was modified by inserting appropriate baffles that were analogous to those in the laboratory model. The analysis of the hydraulic conditions in the laboratory model showed that, under the assumed conditions, wastewater flows through the filter layer in a laminar motion, so such filters can be modeled using the Kozeny–Carman formula. It was shown that, after approximately a year of operation in a filter operating at full technical scale, before modification, dead spaces formed, thus causing the channel and primarily surface flow of wastewater. The phosphorus removal efficiency during this test period averaged 9.4%. After introducing baffles and forcing meander flow in the filter chamber, the efficiency increased to 40.6%. The results indicate that meander flow filters can improve phosphorus removal efficiency in small wastewater treatment plants.

Modified polymer electrolyte membrane for microbial fuel cell: Performance analysis, investigation on anti-biofouling effect, and microbial community analysis on biofouled membrane

Sulphonation is limited in Sulphonated Polyether Ether Ketone (SPEEK) due to its solubility in water beyond an extent. However, to enhance performance of polymer electrolyte membrane (PEM) in microbial fuel cell (MFC), more functional groups are required. To facilitate effective proton transfer, styrene sulphonic acid (SSA) is grafted onto SPEEK, resulting in SPEEK/SSA, to increase the number of functional groups. Based on membrane properties, 5 wt% SSA is found to be the optimum grafting for further filler addition. Copper oxide doped reduced graphene oxide (CuO@rGO) is used as membrane filler at various concentrations to enhance anti-biofouling effect. Swelling is excessive in SPEEK/SSA (30.2%), whereas it is only 17.3% in SPEEK/SSA+1.5 wt%CuO@rGO. As evidenced by the zone of inhibition assay, biofilm inhibition test, and Bradford protein assay, the membrane's anti-biofouling impact is improved by the inherent hydrophilicity of SPEEK/SSA and antibacterial activity of CuO@rGO. The MFC with 1.5 wt% CuO@rGO membrane shows highest maximum power density of 186 ± 5 mW m−2 and Chemical Oxygen Demand removal of 81.23%. Phylogenetic analysis on biofouled membrane shows the predominance of Pseudomonas, Acidovorax and Flavobacterium. The research demonstrates that despite biofouling, the synthesized grafted PEM exhibits high resistance to it and hence performs better.

Propidium monoazide - polymerase chain reaction reveals viable microbial community shifts in anaerobic membrane bioreactors treating domestic sewage at low temperature

An anaerobic membrane bioreactor (AnMBR) treated domestic sewage at 15 °C under different hydraulic retention time (HRT) conditions (6, 12, 16, and 24 h). Propidium monoazide (PMA)-PCR excluded microorganisms without intact cell membranes, focusing on the viable microbial community in anaerobic digestion. The results showed that the 6-hour HRT had poor treatment performance: low chemical oxygen demand removal efficiency (below 80%) and high mean trans-membrane pressure and flux (15 kPa and 9.4 L/(m2 h)). Comparatively, PMA-PCR combined with next-generation sequencing improved the identification of microbial changes compared to conventional 16S rRNA gene sequencing. HRT influenced microorganisms in the hydrolysis and acid-production stages, including carbohydrate-degrading bacteria such as Bifidobacterium and Prevotella 1. Remarkably, a comparison with an AnMBR at 25 °C showed Proteobacteria to be the main cause of membrane fouling in the low-temperature AnMBR, with most operational taxonomic units negatively correlated with HRT and solids retention time.

Landfill leachate treatment with a full-scale membrane bioreactor: impact of leachate characteristics on filamentous bacteria.

Bulking and foaming are extreme filamentous bacterial growths that present serious challenges for the biological leachate treatment process. The current study evaluates the performance of long-term full-scale membrane bioreactor (MBR) treating landfill leachate, specifically focusing on filamentous bacteria overgrowth in the bioreactors. The influence of the variation in leachate structure and operational conditions on floc morphology and filamentous bacteria overgrowth were analyzed for 11months of operation of the full-scale MBR system. The average chemical oxygen demand (COD) and NH4-N removal efficiencies of the system were 87.8 ± 4% and 99.5 ± 0.7%. However, incomplete denitrification was observed when the F/M ratio was low. The high C/N ratio was observed to enhance the frequency of small flocs. Furthermore, a poor to medium diversity of the microbial community was observed. Haliscomenobacter hydrossis, Microthrix parvicella, and Type 021N were found as the most numerous filamentous organisms. Paramecium spp., Euplotes spp., and Aspidisca spp. were found in small quantities. The limited concentration of PO4-P in the leachate compared to high COD and NH4-N concentrations most probably caused phosphate deprivation and increased abundance of identified filamentous microorganisms. This work is the first study in Türkiye that investigates the bulking and foaming problem in full-scale MBR that treats landfill leachate. Hence, it may provide some pioneering perspectives into landfill leachate remediation by monitoring the hybrid biological system.

Effects of light intensity and salinity on formation and performance of microalgal-bacterial granular sludge

Photosynthetic microorganisms in microalgal-bacterial granular sludge offer advantages in wastewater treatment processes. This study examined the effects of light intensity and salinity on microalgal-bacterial granular sludge formation and microbial changes. Activated sludge was inoculated into three bioreactors and operated in batch treatment mode for 100 days under different light intensities (0, 60, and 120 μmol m−2 s−1) and staged increases in salinity concentration (0, 1, 2, and 3%). Results showed that microalgal-bacterial granular sludge was successfully formed within 30 days, and high light exposure increased algal particle stability and inorganic nitrogen removal (63, 66, 71%), while chemical oxygen demand removal (>95%) was similar across groups. High-throughput sequencing results showed that the critical algae were Chlorella and diatoms, while the main bacteria included Paracoccus and Xanthomarina with high extracellular polymeric substance production. This study aims to enhance the comprehension of MBGS processes in saline wastewater treatment under varying light intensities.

Coupling membrane processes with wet air oxidation for the remediation of industrial effluents

Membrane processes (ultrafiltration, membrane bioreactor, reverse osmosis) are relevant for the remediation of wastewater as they generate large volumes of high-quality permeate. However, the remaining concentrates are highly polluted and require further treatment. Membrane concentrates are sufficiently concentrated to undergo a highly efficient wet air oxidation treatment to degrade refractory molecules. Wet air oxidation was performed on five industrial membrane concentrates with varying organic pollutants: bilge wastewater, landfill leachates, a complex industrial effluent, pharmaceutical sludge and dairy wastewater. The results showed three categories: (i) a low effect of the anoxic heating period and significant effect of oxidation duration, (ii) a significant effect of both the anoxic heating period and duration and (iii) an outstanding effect of the anoxic heating period and low effect of oxidation duration. The best removals were achieved at 300 °C, with total organic carbon removals between 75 and 98% and chemical oxygen demand removals between 82 and 99%, along with complete removal of fluorescent footprints. The coupling of membrane processes and wet air oxidation was proven to be robust and flexible for a wide variety of membrane processes and pollutants. A mass balance on the treatment path, including membrane permeate and wet air oxidation outlet, was calculated to assess discharge feasibility. This research demonstrates the potential of the hybrid process for effectively treating membrane concentrates and generating a safer outlet.

Investigating the challenges of biogas provision in water limited environments through laboratory scale biodigesters

ABSTRACT The potential for biogas provision through household-scale anaerobic digestion in rural sub-Saharan Africa is limited due to perceived water shortages. The most common substrate is animal dung diluted 1:1 with water. Two experimental methods tested the potential of reducing water demand. The first experiment compared the chemical oxygen demand (COD) and volatile solid removal of four cow dung dilutions ranging from 3.5-10.6% total solids. In the second experiment, bioslurry filtrate was recirculated back into the fresh substrate at different concentrations. The highest COD removal rate of 28.3% was obtained from mixing equal volumes of dung with filtrate (mean total solids 7.4%) while the highest methane production rate of 0.40 g/L/day, calculated from COD balance, was obtained from undiluted cow dung (total solids 10.6%). Results suggest the potential for a 75-100% reduction in water demand.

Removal of Formaldehyde and Its Analogues Using a Hybrid Assembly of Pyrene-Modified Hydrazide and rGO: A Negative Carbon Emission and Green Chemical Decomposition Method.

Indoor gaseous formaldehyde is the main environmental pollutant that can cause fatal threats to human health. A number of physical and chemical methods have been developed to tackle this issue. However, the existing methods are still unsatisfactory to meet the requirement of sustainable development owing to the flaws of low efficiency and reversible or second pollution. Herein, a chemical method based on a nucleophilic reaction between hydrazine and aldehyde that generates the only by-product of H2O is designed for the removal of formaldehyde. 1-Pyrenebutyric hydrazide was synthesized by a simple esterification reaction and then self-assembled on reduced graphene oxide (rGO) with a large surface area by forming π-π stacking to obtain a composite for chemical removal of gaseous formaldehyde under ambient conditions. In a practical test, the formaldehyde removal rate could reach 91% of the theoretical value, which meets the requirement for commercial formaldehyde removal applications. After 10 times recycling, the formaldehyde removal rate still remains as high as 85%. Moreover, the composite could be regenerated in weak acidic media, which greatly reduce the manufacturing cost in practical applications.

Deglycosylation of Excretory-Secretory Antigens of the Second-Stage Larvae of Toxocara cati Improves Its Efficacy in the Diagnosis of Human Toxocariasis.

Toxocariasis is an important zoonotic infection, especially in tropical areas. One of the significant challenges in the serodiagnosis of human toxocariasis is the cross-reaction of Toxocara antigens with other parasites due to their relatively similar glycan structures. Removing the glycan structure from Toxocara excretory-secretory (TES) antigens may increase the efficacy of these antigens in the diagnosis of toxocariasis. The current study aimed to assess the efficacy of deglycosylated Toxocara cati excretory-secretory (dTES) antigens for the serodiagnosis of human toxocariasis. Toxocara ES antigens were prepared from T. cati second-stage larvae and deglycosylated using sodium hydroxide (NaOH). The TES antigens, along with the dTES antigens, were used in an ELISA as well as a western blotting system for the detection of anti-Toxocara antibodies. Sera samples collected from 30 confirmed cases of toxocariasis, 30 patients with other diseases, and 30 healthy subjects were evaluated by both systems. The sensitivity of TES and dTES ELISA for the diagnosis of human toxocariasis was 96.67% (95% CI = 82.78-99.92) and 93.33% (95% CI = 77.93-99.18), respectively, while the specificity of dTES (88.33%; 95% CI = 77.43-95.18) increased significantly compared to the TES (80.00%; 95% CI = 67.67-89.22). The sensitivity of both antigens was 100% (95% CI = 88.43-100) by the western blotting system. Moreover, the specificity of TES and dTES antigens was 95% (95% CI = 86.08-98.96) and 98.33% (95% CI = 91.06-99.96), respectively, when using the western blotting system. Results of the current study indicate that the chemical removal of the glycan epitopes of T. cati ES antigens significantly reduces cross-reactivity rates with other parasitic infections. Considering the findings of the present study, the dTES antigens seem to be suitable antigens for the serodiagnosis of human toxocariasis.

Assessing the efficacy of bio-composite starch/biochar based microbial fuel cell Pb(II) removal from contaminated seawater

The efficient removal of toxic chemicals from wastewater using effective sorbents has gained significant attention in recent years. In this study, a starch/biochar composite was synthesized from rice straw to achieve the removal of Pb(II) from wastewater. The highest performing starch/biochar composite was then utilized as a microbial fuel cell electrode for generating electricity in synthetic seawater contaminated with Pb(II) and petroleum hydrocarbons. Results showed that the maximal power density and current density were 2.18±0.20 W/m3 and 8.33±0.50 A/m3, respectively, and that the composite achieved removal rates of 95.10±1.50% for Pb(II) and 55.10±2.20% for petroleum hydrocarbons. These findings suggest that the starch/biochar composite can serve as an effective sorbent for remediating environmental contamination, while also having potential for use in sustainable energy generation.

Effective and Economical 3D Carbon Sponge with Carbon Nanoparticles as Floating Air Cathode for Sustainable Electricity Production in Microbial Fuel Cells.

The effective and economical 3D floating air cathodes were fabricated by a simple dipping-drying method with carbon black (CB), ethanol, and PTFE solution. Pristine Type I polyurethane sponge (5 pores/mm) and Pristine Type II polyurethane sponge (3 pores/mm) were used as the support. The deposition of CB on the Pristine Type I and Pristine Type II materials was detected by scanning electron microscopy and Fourier transform infrared spectroscopy. The carbon loss rate test exhibited good CB adhesive stability on both floating air cathodes. Besides, Type I/CB floating air cathode displayed 3.7 times higher tensile strength, 10.58 times higher elongation at break, and 3.3 times lower cost than carbon felt. The electricity production ability of carbon cloth (CC) anode with carbon felt, Type I/CB, and Type II/CB cathode MFCs (CC-CF-MFC, CC-I-MFC, and CC-II-MFC) was evaluated. After 130 days, the CC-I-MFC showed a maximum power density (PD) of 92.58 mW/m3, which was 4.6 times higher than the CC-CF-MFC. Compared with Type II/CB, Type I/CB cathode improved the maximum power density by 160% due to the smaller pores, rougher surface, and higher surface wettability. Further, CC-I-MFC exhibited the best overall oxidation-reduction performance and chemical oxygen demand removal efficiency. Consequently, Type I/CB floating air cathode opens a new opportunity for scaling up simple, inexpensive, and high-performance MFCs for energy production.

Degradation characteristics of refractory organic matter in naproxen pharmaceutical secondary effluent using vacuum ultraviolet–ozone treatment

Vacuum ultraviolet–ozone (VUV-O3) treatment was found to be superior to ultraviolet–ozone (UV-O3) treatment in terms of ozone utilization and hydroxyl radicals (·OH) generation when used to treat the secondary effluent (SE) from a naproxen pharmaceutical plant. VUV-O3 treatment was beneficial in terms of decolorization (100%), chemical oxygen demand removal (43.29%), and total organic carbon removal (54.81%). The VUV-O3 process was applicable over a wide pH range, and the presence of various anions had no significant influence on the oxidation efficiency. After treatment, the genotoxicity, unsaturation degree, and polarity of the SE decreased. In addition, the oxidation sensitivities of the fluorescent organic compounds were ranked as follows: humic acid-like > tyrosine-like > fulvic acid-like > tryptophan-like Moreover, the VUV-O3 process effectively converted refractory organic matter (molecular weights, MW > 2000 Da) into short-chain molecules with low MWs. The removal efficiency of dissolved organic matter (DOM) was 63.27%, and 77.27% of the DOM was found to be reactive to VUV-O3 oxidation. The unsaturation, polarity, and compositional complexity of the DOM decreased after VUV-O3 treatment. Finally, it was deduced that the direct O3 oxidation,·OH, O2·− and 1O2 played a role in the VUV-O3 oxidation process.

Chemo-hydro-mechanics in a reactive rock under cylindrical fluid pressurization

Cylindrical cavity expansion in a geomaterial due to internal fluid pressurization occurs in many geo-energy and geo-environmental engineering problems involving fluid injection into the subsurface. Often, acidic substances are incorporated in the fluid injection posing a chemically aggressive environment at the cavity wall which diffuses into the matrix affecting the rock’s mechanical as well as hydraulic properties via mineral mass removal. Here we propose a coupled chemo-hydro-mechanical model for such scenarios to study the complex interplay between the process of chemical mass removal, damage evolution, rock strength degradation and an alteration of the hydraulic field due to chemical erosion. A homogeneous fully saturated carbonate rock is chosen for qualitative and quantitative assessments as a representative of chemically reactive geomaterials. Plane strain conditions are assumed and all the fields involved in the reaction-transport-deformation process zone are axisymmetric. The rock behaviour is chemically controlled in both the elastic and plastic domain adopting a chemo-elasticity concept and a yield limit depending on the accumulated mass removal, i.e. the total amount of mineral dissolution under high Damköhler number conditions. The rate of chemical dissolution at a continuum scale is described as a function of a variable specific surface area of the solid–fluid interface per unit volume affected by the irreversible micro-cracking process, as well as the local acidity. The irreversible damage evolution is coupled to the hydraulic field via the porosity generation by chemical mass removal, affecting the acid delivery. The presented framework is the first rock cavity expansion model to our knowledge that underpins a spontaneous transition from the diffusion-dominant to a diffusion–advection regime enabled by damage-enhanced chemical mass removal.

Up-flow anaerobic sludge blanket treatment of swine wastewater: Effect of heterologous and homologous inocula on anaerobic digestion performance and the microbial community

The effects of heterogenous (anaerobic sludge from treating distillery sewage, ASDS) and homologous (anaerobic sludge from treating swine wastewater, ASSW) inocula on anaerobic digestion and the microbial community in an up-flow anaerobic sludge blanket treating swine wastewater were compared. The highest chemical oxygen demand removal efficiencies with ASDS (84.8%) and ASSW (83.1%) were obtained with an organic loading rate of 15 kg COD/m3/d. For ASSW compared with ASDS, methane production efficiency was 15.3% higher and excess sludge production was 73.0% lower. The abundance of the cellulose hydrolyzing bacterium Clostridium sensu stricto_1 with ASDS (36.1%) was 1.5 times that with ASSW, while that of Methanosarcina with ASSW (22.9%) was > 100 times that with ASDS. ASDS reduced the content of pathogenic bacteria by 88.0%, while ASSW maintained a low level of pathogenic bacteria. ASSW greatly improved the methane production efficiency of wastewater and is more suitable for treating swine wastewater.

Oxygen vacancies mediate the degradation of refractory organics in the interflow around a simple landfill: Based on Mg-Fe3O4/PMS system

The interflow around simple landfills in villages and towns contains high-risk and trace refractory organics (TRO), which can have serious effects on the rural living environment. Here, an iron-based catalyst containing oxygen vacancies was prepared by doping with Mg, and the Mg-Fe3O4/peroxymonosulfate (PMS) advanced oxidation system was constructed to mediate the efficient degradation of the pollutants in the interflow around simple landfills. The parameters of the system were optimized to maximize the degradation of the pollutants in interflow via single-factor and response surface experiments. Electron paramagnetic resonance revealed that oxygen vacancies can effectively form in the catalyst by doping co-precipitation. The rate of chemical oxygen demand removal from the interflow was 96.01 ± 1.12% under the following conditions: 10% Mg doping, 1.03 g·L−1 catalyst dosage, and 13.47 mmol·L−1 PMS dosage. UV254 and E280 decreased from 0.403 and 0.305 cm−1 to 0.199 and 0.164 cm−1, respectively, and E300/E400 increased from 5.56 to 8.92 after the reaction. Excitation–emission matrix spectra showed that the corresponding absorption peaks of fulvic acid and tyrosine analogs were heavily attenuated. Gas chromatography–mass spectrometry analysis showed that the number of TRO decreased from 57 to 9, indicating that a large amount of TRO had been removed. A mechanistic analysis revealed that SO4·- and OH· might play a major role in the reaction process and that 1O2 plays an important role in the degradation process.

Ionic Liquid Cross-Linked High-Absorbent Polymer Hydrogels: Kinetics of Swelling and Dye Adsorption.

The use of polymer gels for the removal of toxic chemicals from wastewater is an important area in terms of both academic and industrial research. This work presents a simple approach to the fabrication of chemically cross-linked cationic hydrogel adsorbents using designed ionic liquid-based cross-linkers and their successful use in the removal of organic dyes. Two different ionic liquid cross-linkers, [VIm-4VBC][Cl] (ILA)/[DMAEMA-4VBC][Cl] (ILB), are synthesized by the simple nucleophilic substitution reaction of 4-vinylbenzyl chloride (4VBC) separately with 1-vinylimidazole (VIm) and 2-(dimethylamino)ethyl methacrylate (DMAEMA). Cross-linked poly(acrylamide) (CPAam) and poly(2-hydroxyethyl methacrylate) (CPHEMA) hydrogels are then prepared from the corresponding monomers and as-synthesized cross-linkers (ILA and ILB) by free radical polymerization in the presence of a redox initiator combining ammonium persulfate (APS) and N,N,N',N'-tetramethylethylenediamine (TEMED). The dried CPAam and CPHEMA xerogels exhibit macroporous morphology and high thermal stability. The hydrogel samples exhibit high swelling behavior, and the diffusion of water molecules into the hydrogels follows pseudo-Fickian kinetics. The cationic cross-linking sites in the hydrogel networks allow preferable binding with anionic dyes, and these dye uptake capacities are determined using different model anionic dyes via UV-vis spectroscopy. The dye adsorption onto these hydrogels follows a pseudo-second-order kinetic model. The adsorption mechanism is also analyzed by employing intraparticle diffusion and Boyd kinetic models. The relationship between the maximum equilibrium adsorption capacity (qm) of the hydrogels for eosin B (EB) dye and the equilibrium EB concentration can be better described by Langmuir and Freundlich isotherm models, and the estimated qm using the Langmuir isotherm can reach more than 100 mg g-1. The cross-linked hydrogels can be easily regenerated and have a recycling efficiency of >80% for up to three consecutive dye adsorption-desorption cycles, which is promising for their use in wastewater treatment.

Microalgae cultivation in stabilized landfill leachate for simultaneous treatment and biomass production

BackgroundThe high toxicity of landfill leachate has motivated to an investigation of economical and ecological treatment prior releasing into environment. Recently, microalgae have emerged as an alternative method due to its ability to recover nutrient and potential for bio-fuel production. However, the high concentrations of inhibitory compounds and ammoniacal nitrogen in young landfill leachates require high dilutions for microalgae to thrive. Hence, this study aims to evaluate the performance of microalgae by using stabilized landfill leachate with lower to no dilutions in nutrient removal, biomass and lipid production. MethodsLeachate concentrations of 33, 44, 66, 89 and 100 v/v% were initially treated with the microalgae C. vulgaris. Parameters of chemical oxygen demand (COD), ammoniacal nitrogen (NH3–N), orthophosphate (PO43−), total phosphorus (TP) and colour removal were evaluated. Cost analysis was conducted to evaluate the economical appropriateness. Significant findingsThe highest removals were achieved at 43.67% of COD, >97% of NH3–N, 79.26% of PO43−, 77.64% of TP and 44.04% of colour. Highest biomass yield obtained was 220 mg/L by 89 v/v% of leachate concentration with 8.14% of lipid yield. Cost of treatment was calculated to be ∼$0.02 per m3 leachate. The feasibility of stabilized landfill leachate treatment without any dilutions using microalgae was attained as they can survive amidst this condition, perform nutrient removals, and produce biomass simultaneously.

The Possibility of Microplastic Removal by Earthworms and Comparing With Conventional Chemical Removal Methods (A Global and Deeply Systematic Review)

The Possibility of Microplastic Removal by Earthworms and Comparing With Conventional Chemical Removal Methods (A Global and Deeply Systematic Review)