Treatment Of Phenolic Wastewater Research Articles

Fe3O4–CuO@Lignite activated coke activated persulfate advanced treatment of phenolic wastewater from coal chemical industry

In this study, lignite activated coke (LAC) was used as the carrier for the first time, Fe3O4–CuO composite metal oxide was used as the main active material, and the nano-scale magnetic supported composite metal oxide Fe3O4–CuO@LAC catalyst was synthesized for the first time, which can effectively activate the active oxygen in peroxodisulfate (PS). XRD, FTIR, BET, SEM, XPS and other analysis results showed that there was particulate matter with spherical structure on the surface of the active coke, and its diffraction peaks matched well with the characteristic peaks of Fe3O4 and CuO, and it was a mesoporous structure with a specific surface area of 619.090 m2 g−1. By optimizing the experimental conditions, the results showed that more than 92% of hydroquinone can be removed under the conditions of hydroquinone concentration of 50 mg/L, pH = 5, adding 0.1 g/L catalyst and 3 mmol/L PS. EPR and quenching experiments proved that there were four reactive oxygen species in the reaction system ·OH, SO4−·, O2−· and 1O2. According to the degradation products of hydroquinone detected by LC-MS, the possible degradation path was deduced which laid a foundation for solving the problem of difficult treatment of phenol-containing wastewater in coal chemical industry.

Synthesis of novel epichlorohydrin cross-linked β-cyclodextrin functionalized with reduced graphene oxide composite adsorbent for treatment of phenolic wastewater.

A novel composite consisting reduced graphene oxide-functionalized beta-cyclodextrin epichlorohydrin polymer (RGO-βCD-ECH) was synthesized for the treatment of phenolic wastewater. Batch study of phenolic pollutants (2,4-dichlorophenol, 2-chlorophenol, and phenol) was analyzed using the synthesized composite as an adsorbent from an aqueous solution. The optimized parameters were temperature 25°C, adsorption time 60min, solution pH 7, and dosage 0.25g/L. The isotherm data were more suitably fitted by the Langmuir isotherm model. The maximum uptake for 2,4-dichlorophenol, phenol, and 2-chlorophenol was 702.853, 659.475, and 674.155mg/g, respectively, at 25 ± 1°C. The kinetic data for all the phenolic pollutants follow the pseudo-second-order model, and the rate was controlled by film diffusion. Thermodynamic data revealed that the process of removing phenolic pollutants is spontaneous and endothermic. The composite can be used up to five cycles with a small reduction in the removal. Adsorption performance of the synthesized composite for synthetic industrial effluents shows that up to 78% removal occurred in 60min adsorption time. Based on the remarkably rapid adsorption and high adsorption capacity, the synthesized composite can be considered an efficient adsorbent for treating phenolic pollutants from wastewater.

Efficient treatment of phenol wastewater by co-culture of Chlorella vulgaris and Candida tropicalis

The increased water contamination with phenolic compounds has emerged as an important environmental concern due to their considerable ecotoxicities and associated health issues. Here, a co-cultured microalgae/microorganism system, Chlorella vulgaris and Candida tropicalis, has been developed for efficient treatment of phenol and microalgal biomass accumulation. Our results show that the C. vulgaris and C. tropicalis co-culture system can achieve the highest phenol removal rate as 233.3 mg/L/d and the total chlorophyll accumulation as 23.0 mg/L with the initial volume ratio of C. vulgaris and C. tropicalis at 1:3, which are 5.2 and 7.2 times higher than that of C. vulgaris monoculture respectively. The maximum phenol removal ability of the constructed co-culture system was tested as 1500 mg/L within 6 days. Transcriptome analysis suggested that the co-cultured C. vulgaris/C. tropicalis can utilize phenol as carbon source for its growth and metabolism, and the removal mechanism of phenol was mainly due to the biodegradation process other than bio-absorption. Simulated wastewater experiment shows that the co-culture system can not only efficiently remove the phenol compounds, also can significantly decrease the ammonia nitrogen (NH3−N), total phosphorus (TP) and chemical oxygen demand (COD) of wastewater with removal efficiencies as high as 93%, 92%, 80% and 100%, respectively. Our work provided a promising way for the treatment of phenol compounds and then promoting the growth of C. vulgaris using phenol containing wastewater.

Enhanced degradation of high-concentrated 2,4,6 trichlorophenol-containing wastewater by micron-grade high iron-containing fly ash/loofah sponge biochar: Metagenomic functional succession

In order to strengthen the treatment of phenolic wastewater by anaerobic biotechnology, micron-grade high iron-containing fly ash/loofah sponge biochar (MHIFA/LsBC) was prepared and added to anaerobic activated sludge. It was domesticated and cultured in anaerobic bottle by a constant temperature oscillation incubator. Its promoting effect on the anaerobic degradation of high-concentrated 2,4,6-trichlorophenol (2,4,6-TCP) wastewater and its effect on the composition and function of microbial community were studied. The results indicated that with MHIFA/LsBC, the final removal rates of COD and 2,4,6-TCP in R1 (75.6% and 75.1%) were 2.1 and 1.81 times than those of the control group, respectively. The maximum methane yield was 107.25 mL/d. MHIFA/LsBC addition resulted in higher biomass and conductivity, and simultaneously increased the concentration of EPS and coenzyme F420. Microbial community analysis indicated that the enriched electrogenic bacteria Pseudomonas might perform DIET with Methanothrix through bioelectrical connection assisted by MHIFA/LsBC, and promote the anaerobic degradation of 2,4,6-TCP. As the functional genus induced by MHIFA/LsBC, Pseudomonas promoted the degradation and transformation of phenolic pollutants, and Azotobacter played a keystone role in metabolism for hydrogen production by preserving the NADH/NAD+ balance.

Rethinking electrochemical oxidation of bisphenol A in chloride medium: Formation of toxic chlorinated oligomers

Using boron-doped diamond (BDD) anodes to degrade bisphenol A (BPA) had been an active area of research interest within the past 20 years. A major concern about the process lie in the formation of toxic chlorinated aromatic by-products when chloride electrolytes were present in the reaction system. In this contribution, we highlighted the formation of complex poly-chlorinated oligomer by-products in electrochemical oxidation processes, which had often been overlooked in previous studies. Moreover, the distribution and complexity of the chlorinated oligomers were found to be strongly linked to the adopted initial chloride concentration. Formation of simple chlorinated by-products was ascribed to the electrophilic substitution reactions mediated by active chlorine species, while the oligomer by-products (including chlorinated dimers, trimers and tetramers) were generated through the coupling reactions between various chlorinated phenoxy radicals. The possible mechanisms describing the formation of these by-products were also proposed. The obtained results shed light on the possible risk of BDD technology in the treatment of phenolic wastewater containing chloride electrolytes.

Preparation of active carbon through one-step NaOH activation of coconut shell biomass for phenolic wastewater treatment

Preparation of active carbon through one-step NaOH activation of coconut shell biomass for phenolic wastewater treatment

Extraction and recovery of phenolic compounds from aqueous solution by thermo-separating magnetic ionic liquid aqueous two-phase system

• Thermo-separating magnetic ionic liquids are discovered for the first time. • The first thermo-separating magnetic ionic liquid aqueous two-phase system is successfully developed. • This system is successfully applied to remove phenols from aqueous solution. • MIL and phenolic compound are simultaneously recovered simply by heating. • MIL can be recycled for at least 6 times with satisfactory performances. In this report, thermo-separating magnetic ionic liquids (MILs) were discovered for the first time. Two Polypropylene glycol 600 (PPG 600 ) based thermo-separating MILs were synthesized, characterized and successfully applied to construct the first reported thermo-separating magnetic ionic liquid aqueous two-phase system (MILATPS). This novelly proposed thermo-separating MILATPS combined the advantages of rapid extraction, volatile organic solvent free, magnetic separation and thermo-recovery of MIL in an extraction process. Phase behaviors and extraction-recovery processes of phenol, o -cresol and m -cresol were systematically studied. Several influencing factors on phenolic compound extraction efficiencies were detailedly investigated and optimized. Under optimal conditions, both two synthesized thermo-separating MILs revealed good performances with extraction efficiencies higher than 90%. Scale-up studies were also satisfactory. Additionally, both high purities of MILs and phenolic compounds could be ideally recovered simply by heating and the recoveries of phenolic compounds were higher than 95% for all systems. Furthermore, the two MILs could be recycled for at least 6 times with steadily high extraction efficiencies. This novelly proposed thermo-separating MILATPS is simple and green method which is showing great potential in an extraction-recovery process and the industrial treatment of phenolic wastewater.

Halophilic archaea and their extracellular polymeric compounds in the treatment of high salt wastewater containing phenol

Phenol is one of the major organic pollutants in high salt industrial wastewaters. The biological treatment of such waste using microorganisms is considered to be a cost-effective and eco-friendly method. However, in this process, salt tolerance of microorganisms is one of the main limiting factors. Halophilic microorganisms, especially halophilic archaea are thought to be appropriate for such treatment. To develop a novel effective biological method for high salt phenol wastewater treatment, the influence of phenol in high salt phenol wastewater on halophilic archaea and their extracellular polymeric substances (EPS) should be investigated. In the present study, using phenol enrichment method, 75 halophilic archaeal strains were isolated from Wuyongbulake salt lake sediment sample. The majority of the identified strains were phenol-tolerant. Six strains with high phenol tolerance were chosen, and the phenol scavenging effect was observed in the microbial suspension, supernatant, and EPS. It was noticed that the phenol degradation rate of suspensions of both strains 869-1, and 121-1 in salt water exhibited the highest rates of 83.7%, while the supernatant of strain 869-1 reached the highest rate of 78.2%. When combined with the comprehensive analysis of the artificial wastewater simulation experiment, it was discovered that in the artificial wastewater containing phenol, the phenol degradation rate of suspension of strain A387 exhibited the highest rates of 55.74% both, and supernatant of strain 630-3 reached the highest rate of 62.3%. The EPS produced by strains A00135, 558-1, 869-1, 121-1 and A387 removed 100% phenol within 96 h, and the phenol removal efficiency of EPS produced by 869-1 reached 56.1% under an artificial wastewater simulation experiment with high salt (15%NaCl) condition. The present study suggests that halophilic archaea and their EPS play an important role in phenol degradation. This approach could be potentially used for industrial high-salt wastewater treatment.

Design of solvent mixtures for removal of phenol from wastewater using a non-linear programming model with a multi-start method

The optimization-based design of solvent mixtures used for phenolic wastewater treatment was investigated in this work. A nonlinear programming （NLP） model was formulated based on the concepts of computer-aid molecule design (Computer-Aided Molecular Design, CAMD) to select solvent mixtures with the best extraction performance considering the constraints of extraction process and the environmental impact. Due to the complexity of the NLP model, multi-start method was adopted to solve this problem in order to get near global optimal solution. The results of the calculations suggested that the optimal mixture consisted of 70.1% n-octanol and 29.9% 2-octanone (molar fraction).The 119 sets of experimental results showed that the extraction ability of the optimal solvent mixture identified by CAMD technique was among the top 6 sets compared to the experiment results. The results suggested that the developed NLP model could be able to screen the optimal solvent mixture in phenolic wastewater treatment.

Persulfate oxidation enhanced extraction to improve the removal of high concentration phenol wastewater

An efficient and low-cost method for utilization of waste sludge and treatment of high salt and high phenol wastewater.

Yacon (Smallanthus sonchifolius) peel as a promising peroxidase source for the treatment of phenolic wastewater

Peroxidases are versatile enzymes that catalyse the oxidation of many inorganic and organic substrates. There are numerous vegetable sources of peroxidases, including the yacon (Smallanthus sonchifolius), an easy-to-grow plant. This study aimed to extract, purify and characterise the peroxidases obtained from yacon roots. We partially purified the enzyme from yacon pell using an aqueous two-phase system (ATPS) and obtained 4.66 purification-fold and 33.87% activity recovery. The enzyme showed an optimal temperature of catalysis 60 °C and optimal pH 11 using pyrogallol as substrate. Considering the oxidation of 2,4-dichlorophenol, these conditions were 37.5 °C and pH 7. Furthermore, the enzyme presented substrate inhibition at high hydrogen peroxide concentrations. The presence of 5 mM Cu2+ inhibited, while and 5 mM Co2+ activated the enzyme. The enzyme remained stable at 50 °C for 60 min and showed improved thermostability compared to horseradish peroxidase. The kinetic mechanism of yacon peroxidase was investigated, and our studies suggested the enzyme follows a Ping-Pong Bi–Bi mechanism. Finally, 2,4-dichlorophenol was selected as a target pollutant, and we obtained as many as 86.26% of bioconversion using yacon peroxidase. The results presented in this article suggest that yacon is a promising source of peroxidase and can be an alternative for bioprocesses applications.

Investigation and evaluation of membrane fouling in a microbial fuel cell-membrane bioreactor systems (MFC-MBR)

Two membrane bioreactors with and without adding an electric circuit (named as MFC-MBR and C-MBR, respectively) were established to investigate the effects of micro-electric field on membrane fouling. With the aeration rate of 1.5 L/min, the synergistic effect of aeration and micro-electric field was the best in reducing membrane fouling and COD in treatment of a simulated phenol wastewater. Compared with C-MBR, the running time of MFC-MBR was extended for 16 days. Scanning electron microscope (SEM) and energy-dispersive X-ray detector (SEM-EDX) demonstrated that less foulants were attached to the membrane and the attachment was loosend in MFC-MBR. The decreased absolute value of zeta potential indicated repulsion among the negatively-charged sludge particles was reduced and flocculation of the sludge was improved, which alleviated the membrane fouling. The soluble microbial products (SMP) and loosely-bound extracellular polymeric substances (LB-EPS) were also decreased in MFC-MBR. It was found that migration and neutralization of the negatively-charged particles, and degradation of microorganisms contributed to the alleviation of membrane fouling. Moreover, the decreases of carbohydrates in LB-EPS led to higher protein/carbohydrates (PN/PS) ratio, which was a key parameter for alleviating membrane fouling. Meanwhile, the increase of tightly bound extracellular polymeric substances (TB-EPS) could also slow down membrane fouling. Because TB-EPS can be used as a binder to strengthen the flocculation of sludge particles.

Preparation and characterization of a novel Ni-doped TiO2 nanotube-modified inactive electrocatalytic electrode for the electrocatalytic degradation of phenol wastewater

A Ni-TiO2-NTs substrate and SnO2-Sb catalytic layer are formed on a Ni-Ti surface by the anodic oxidation method and sol-gel method, respectively, and a Ni-Ti/Ni-TiO2-NTs/SnO2-Sb electrode is successfully prepared for use as an electrocatalytic oxidation anode for wastewater treatment. Scanning electron microscopy (SEM) analysis shows that the Ni-TiO2-NTs base layer has a highly ordered and vertically formed nanotube array morphology, and the SnO2-Sb catalyst layer has a uniform and dense nanoparticle morphology. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses show that the base layer is made of Ni-TiO2 and the catalyst layer consists of SnO2-Sb. Electrochemical analysis shows that the oxygen evolution potential (OEP) of the electrode is increased to 2.3 V, and the working life is extended to 653 h. Using phenol as the treatment target, the phenol degradation rate reaches 87% in 3 h, and the COD removal rate reaches 54.2%. Compared with the traditional Ti/SnO2-Sb electrode, the current efficiency increases by 1.57 times, and the energy consumption decreased by 59.92%. Therefore, the Ni-Ti/Ni-TiO2-NTs/SnO2-Sb electrode is a promising electrochemical anode material for the treatment of phenol wastewater.

Mushroom tyrosinase immobilized in metal–organic frameworks as an excellent catalyst for both catecholic product synthesis and phenolic wastewater treatment

AbstractBACKGROUNDMetal–organic frameworks (MOFs) have gained increasing attention with ever‐expanding applications. Developing new MOF‐based immobilized enzymes with new applications is required, not only for demonstrating the generality and applicability of using MOFs for enzyme immobilization, but also to provide potential biocatalysts for industrial applications. To the best of the authors’ knowledge, this is the first report of immobilizing mushroom tyrosinase on zeolitic imidazolate frameworks (ZIFs), with two new applications being developed.RESULTSUpon immobilization through a one‐pot in situ encapsulation approach, the resultant tyrosinase@ZIF‐8 was characterized in structural features and catalytic properties. It was much more stable against pH and temperature relative to the free enzyme. The new biocatalyst was highly efficient in catalyzing the synthesis of catecholic products with pharmacological benefits (l‐DOPA, piceatannol and 3′‐hydroxypterostilbene) and in eliminating phenolic pollutants (phenol, p‐cresol, p‐chlorophenol). Excellent productivities were obtained for the synthesis of the three catecholic products (0.14, 1.38 and 1.46 g L−1 h−1, respectively). A complete removal of the three phenolic pollutants was achieved within 2.5 h, superior to other processes mediated by the same enzyme, or others, immobilized on different supports. The reusability of the new biocatalyst can be remarkably improved by entrapment into polyvinyl alcohol‐alginate gel.CONCLUSIONSTyrosinase can be immobilized on a new type of MOF with advantages such as easy preparation and excellent catalytic performance. This novel immobilization strategy for tyrosinase offers an excellent biocatalyst potent for both catecholic product synthesis and phenolic wastewater treatment. © 2021 Society of Chemical Industry (SCI).

Experimental study of manganese dioxide doped with metal for the treatment of phenolic wastewater

The wastewater containing phenol is harmful, and the process is complicated, photocatalytic oxidation technology is believed to be the greenest and promising strategy for contaminants removal because of the solar energy utilization and no additional oxidants. Herein, manganese dioxide(MnO2) doped with metal was fabricated by a low-temperature hydrothermal method, the specific surface area of MnO2 photocatalyst was significantly enhanced by doping metal ion. This making the photocatalytic performance improved obviously, and further applying for phenol degradation under visible light irradiation at room temperature.

Effect of Culture Condition and Growth Kinetics on Phenol Biodegradation by an Indigenous Rhodococcus pyridinivorans Strain PDB9T NS-1

The US Environmental Protection Agency listed phenolic compounds as priority pollutants, and their occurrence in water systems poses serious health risks to humans and other living species. The culture conditions are extremely crucial for microbial growth, enzymatic and cellular metabolic activities. Thus, the effects of different culture parameters like pH, temperature (°C), and agitation speed (RPM) on the indigenous Rhodococcus pyridinivorans strain PDB9T NS-1 were modeled using response surface methodology (RSM) and central composite design (CCD). The results showed that the main effect of pH and interaction between pH and agitation speed had a significant to a moderately significant effect on phenol degradation by the indigenous R. pyridinivorans strain PDB9T NS-1. Almost complete phenol degradation was obtained at an optimal setting of pH 7.5, 187 rpm, and 34 °C in 18 h. Growth and phenol degradation kinetics of the actinomycetes was examined in a batch shake flask under the optimized conditions. The growth of Rhodococcus species at varying initial levels of the phenol followed a Pamukoglu and Kargi substrate inhibition model with half-saturation constant (Ks ) of 54.21 mg/l, maximum specific growth rate (µ max) of 0.169 (1/h), substrate inhibition constant (Ksi ) of 243.26 mg/l. The results obtained from the optimization of culture conditions and growth kinetics by the indigenous R. Pyridinivorans strain PDB9T NS-1 suggest the potential of the system in the treatment of phenolic wastewater.

Cu(II) doped FeOCl as an efficient photo-Fenton catalyst for phenol degradation at mild pH

In this work, the Cu(II) doped iron oxychloride composites (Cu-FeOCl) were successfully synthesized and applied to the photo-Fenton degradation of phenol for the first time. Effect of various objective parameters on catalytic performance have been systematically evaluated, such as the doping amount of Cu(II), catalyst dose, pH value and H2O2 dose. The Cu(II) doping in FeOCl accelerated significantly the decomposition of H2O2 to generate hydroxyl radicals (•OH). Furthermore, the introduction of Cu(II) would produce lattice defects on the surface of FeOCl, which was benefit for the separation efficiency of the photogenerated electron-hole pairs. The 0.5Cu-FeOCl composite exhibited excellent degradation performance over a wide pH range of 3–8. The 0.5Cu-FeOCl/H2O2/Vis system degraded 95.2% of phenol (20 mg/L) within 14 min and removed 79.9% TOC within 120 min with low dosage of H2O2 (3 mM). The main intermediates of phenol degradation were identified by LC-MS, and a possible photo-Fenton catalytic mechanism for phenol degradation by 0.5Cu-FeOCl catalyst was proposed. This study would provide some new insights into developing photo-Fenton catalysts and treatment of phenolic organic wastewater.

Fe-Mn doped powdered activated carbon pellet as ozone catalyst for cost-effective phenolic wastewater treatment: Mechanism studies and phenol by-products elimination

A novel bimetallic doped PAC (Fe-Mn/PAC) pellet was prepared with a facile sol-gel method and used as an ozone catalyst for phenolic wastewater (PWW) treatment. Adoption of Fe-Mn/PAC pellet in microbubble ozonation enhanced the 1-h chemical oxygen demand (COD) and phenol removal in PWW to 79% and 95%, respectively. With ozone dosage of 10 mg/L, 1 g/L Fe-Mn/PAC pellet exhibited ozone conversion of 92%. In comparison to microbubble ozonation process, Fe-Mn/PAC induced microbubble-catalytic ozonation process promoted ozone decomposition rate by 1.9 times. In terms of •OH production, Fe-Mn/PAC pellet enhanced •OH exposure by 10 times, with a Rct value of 2.92 × 10 -8. Rct kinetic model also suggested that Fe-Mn/PAC pellet obtained higher kinetic rate constants for initiating and promoting •OH generation. Usage of Fe-Mn/PAC pellet in microbubble ozonation for phenolic wastewater treatment also reduced the total ozone consumption by 70%. In Fe-Mn/PAC induced microbubble-catalytic ozonation process, the ratio between ozone consumption and COD removal (ΔO3/ΔCOD) was 0.91. Fe-Mn/PAC pellet characterization with X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FT-IR) and X-ray powder diffraction (XRD) analysis revealed successful doping of Fe-Mn on PAC substrate and larger numbers of carbon-oxygen/hydroxyl surface groups, which played key roles in ozone decomposition and •OH production.

Efficient Treatment of Phenol Wastewater by Catalytic Ozonation over Micron-Sized Hollow MgO Rods.

Phenol is a nocuous water pollutant that threatens human health and the ecological environment. CoOx-doped micron-sized hollow MgO rods were prepared for the treatment of phenol wastewater by catalytic ozonation. Magnesium sources, precipitants, initial precursor concentration, Co/Mg molar ratio, and catalyst calcination temperature were optimized to obtain the best catalysts. Prepared catalysts were also well characterized by various methods to analyze their structure and physical and chemical properties. In this process, CoOx/MgO with the largest large surface area (151.3 m3/g) showed the best catalytic performance (100 and 79.8% of phenol and chemical oxygen demand (COD) removal ratio, respectively). The hydrolysis of CoOx/MgO plays a positive role in the degradation of phenol. The catalytic mechanism of the degradation of O3 to free radicals over catalysts has been investigated by in situ electronic paramagnetic resonance (EPR). The catalyst can be reused at least five times without any activity decline. The prepared CoOx/MgO catalyst also showed excellent catalytic performance for removal and degradation of ciprofloxacin, norfloxacin, and salicylic acid.

Co-metabolism based adaptation of anaerobes to phenolic saline wastewater in a two-phase reactor enables efficient treatment and bioenergy recovery

Anaerobic biological treatment of saline phenolic wastewater has some limitations such as slow adaptation, low biodegradability, and salinity-derived washout of biomass, though this technology has some benefits in terms of bioenergy recovery, simplicity in operation, and economic rationality. Therefore, we propose a packed-bed circular baffled reactor (PB-CBR) along with a co-metabolism strategy for phenol adaptation at salinity level of 10 g-NaCl/L. Phenol and glucose were gradually increased and decreased to 0.9 and 1.0 g/L, respectively. Stable and efficient performance was achieved with > 99.9% phenol removal, ∼98% overall biodegradability, and ∼ 0.3 L CH4/gCOD. A sudden increase in phenol to 2 g/L was then examined, where phenol removal dropped to ∼ 19% after 30 d; after another 30 d, the removal was negligible even when phenol was decreased to 1.7 g/L. The compartment-wise analysis of PB-CBR showed that phases-separation, along all compartments, maintained the overall efficiency, particularly when facing salinity or phenol shocks; otherwise, earlier compartments achieve ∼ 95% of efficiency. The microbial community analysis showed that Corynebacteriaceae, Syntrophaceae, Kosmotogaceae, and Synergistaceae were key players in phenol-degradation. Using readily biodegradable co-substrate enhanced the biodiversity. Eventually, and according to a cost-benefit analysis, the present work offers a promising opportunity to treat phenol-based saline effluents in an efficient, sustainable, and affordable way.