Water Treatment Methods Research Articles

Investigating Effects of Reverse Osmosis-Treated Water on the Corrosion Rate of Chains in Armoured Face Conveyor for Longwall Mining

Premature failure of armoured face conveyor (AFC) chains due to corrosion is a significant proportion of the unplanned downtime experienced on longwall equipment. The AFC chains are constantly in contact with water and wet coal. The premature failure issue of AFC chains has become more prominent since the introduction of longwall top-coal caving with its additional AFC. Reverse osmosis (RO) is a popular water treatment method for reducing salinity and dissolved solids, but its impact on the corrosion of the AFC chains is unclear. This study has been commissioned to investigate the direct effects of RO water on the corrosion of AFC chains. An immersion test was carried out using AFC chain steel submerged in two water samples: untreated dam water and treated water from an RO treatment plant. Elemental analysis was conducted for both water samples, and four corrosion indices were measured for both water samples. The RO water more vigorously dissolves calcium carbonate scales leading to increased corrosion of the AFC chains although the dam water has much higher levels of calcium, chloride, sulphate, sodium, and magnesium. Bicarbonate ions are the main alkaline factor of water that provides the buffering capacity to acids. Decreased alkalinity without balancing other ions in water causes high corrosivity and decreased scaling tendencies.

Basil seeds loaded with MOFs as an eco-friendly and sustainable adsorbent for efficient removal of hazardous organic pollutants from water

Metal-organic frameworks (MOFs) have the potential to eliminate organic contaminants from water due to their salient features. Unfortunately, the synthesis of MOFs in powdered forms, and the issues related to separation leading to the release of metal ions, are highly inefficient methods for water treatment. Therefore, it remains crucial to overcome such drawbacks and process MOFs into specially designed structures for real-time applications. Concerning this, we report a novel, facile, and eco-friendly strategy of loading MOF into basil seeds for the adsorption of organic pollutants from water. Herein, the MOF particles bind to the mucilage/fibre by strong electrostatic interactions. Consequently, the composite beads exhibit good cationic dye adsorption, with adsorption efficiencies of over 95 %. The adsorption results align well with the pseudo-first-order and Langmuir isotherm models. Moreover, these composite beads exhibit stability even in harsh conditions and saline solutions. Notably, they demonstrate exceptional dye removal (>95 %) at pH 5–8, which corresponds to the region at which the water is significantly consumed. Considering real-time applications, the composite beads efficiently adsorb industrial waste (>95 % removal). Impressively, the composite can be reused for up to 5 cycles and the entire material, being a biopolymer composite, makes the material eco-friendly, offering a new stage for organic decontamination.

Promoting Effect of Silver Oxide Nanoparticles on the Oxidation of Bisphenol B by Ferrate(VI).

Bisphenol B (BPB, 2,2-bis(4-hydroxyphenyl) butane), as a substitute for bisphenol A, has been widely detected in the environment and become a potential threat to environmental health. This work found that silver oxide nanoparticles (Ag2O) could greatly promote the removal of BPB by ferrate (Fe(VI)). With the presence of 463 mg/L Ag2O, the amount of Fe(VI) required for the complete removal of 10 μM BPB will be reduced by 70%. Meanwhile, the recyclability and stability of Ag2O have been verified by recycling experiments. The characterization results and in situ electrochemical analyses showed that Ag(II) was produced from Ag(I) in the Fe(VI)-Ag2O system, which has a higher electrode potential to oxidize BPB to enhance its removal. A total of 13 intermediates were identified by high-resolution mass spectrometry, and three main reaction pathways were proposed, including oxygen transfer, bond breaking, and polymerization. Based on the toxicity assessment through the ECOSAR program, it is considered that the presence of Ag2O reduced the toxicity of BPB oxidation intermediates to aquatic organisms. These results would deepen our understanding of the interaction between Fe(VI) and Ag2O, which may provide an efficient and environmentally friendly method for water and wastewater treatment.

Review of Advanced Water Treatment for Removal of Nanoplastic Pollution

Drinking water is a very important basic need for humans. One of the detected drinking water pollution that greatly affects the quality is the content of nanoplastics. In aquatic ecosystems, nanoplastics are materials that cannot be decomposed. Through this brief review, the efficiency of removing nanoplastics using various water treatment methods will be reviewed. Some of the treatment methods reviewed are nanoplastic removal using filtration, adsorption, coagulant and flocculant addition, and CFS (Coagulation/Flocculation Sedimentation). The research method used is a literature review related to drinking water treatment to eliminate pollution by nanoplastics. The conclusion from the literature review is that the process of treating drinking water by filtration with the addition of coagulants is the most efficient treatment for removing pollution by nanoplastics, reaching 99.9%.

Public Perceptions of Water Quality in the Lake Bunyonyi Sub-Catchment, Western Uganda

Lake Bunyonyi ecosystem plays vital roles in water resource conservancy and tourism. Nevertheless, the rapid increase in human population and the unrelenting human activities are threatening the values, functions, and ecological integrity of the lake. In this study, the public perceptions of drinking water quality and its health implications in the Lake Bunyonyi Sub-catchment, Western Uganda are presented. A closed-ended questionnaire was administered to 267 respondents living within one Kilometre away from the lake shores. Besides, observation and interview methods were used to complement data collected by the questionnaire method. Results indicate that the prominent activities around the lake are peasantry and small-scale businesses attributed to soil fertility and rural tourism. Despite the lake being a popular source of drinking water in the sub-catchment, the quality of its water suffers from diffuse pollution and little has been done to avert it. This study recommends regular surveillance and water quality testing to increase people’s awareness of water quality. Besides, the local authorities should train people the alternative environmentally-friendly farming practices like afforestation with correct tree species and agro-forestry practices to increase vegetation cover and reduce soil erosion debris washed into the lake system. Environmental-friendly household water treatment methods (biosand filtration and solar disinfection) should be promoted to improve the quality of drinking water.

Recycling of nutrient medium to improve productivity in large-scale microalgal culture using a hybrid electrochemical water treatment system

Recycling and reusing of nutrient media in microalgal cultivation are important strategies to reduce water consumption and nutrient costs. However, these approaches have limitations, e.g., a decrease in biomass production, (because as reused media can inhibit biomass growth). To address these limitations, we applied a novel membrane filtration‒electrolysis‒ultraviolet hybrid water treatment method capable of laboratory-to-large-scale operation to increase biomass productivity and enable nutrient medium disinfection and recycling. In laboratory-scale experiments, electrolysis effectively remove the biological contaminants from the spent nutrient medium, resulting in a high on-site removal efficiency of dissolved organic carbon (DOC; 80.3 ± 5 %) and disinfection (99.5 ± 0.2 %). Compared to the results for the recycling of nutrient medium without water treatment, electrolysis resulted in a 1.5-fold increase in biomass production, which was attributable to the removal of biological inhibitors from electrochemically produced oxidants (mainly OCl−). In scaled-up applications, the hybrid system improved the quality of the recycled nutrient medium, with 85 ± 2 % turbidity removal, 75 ± 3 % DOC removal, and 99.5 ± 2 % disinfection efficiency, which was beneficial for biomass growth by removing biological inhibitors. After applying the hybrid water treatment method, we achieved a Spirulina biomass production of 0.47 ± 0.03 g L−1, similar to that obtained using a fresh medium (0.53 ± 0.02 g L−1). The on-site disinfection process described herein is practical and offers a cost-saving and environmental friendly alternative for nutrient medium recycling and reusing water in mass and sustainable cultivation of microalgae.

Sulfate Radical in (Photo)electrochemical Advanced Oxidation Processes for Water Treatment: A Versatile Approach.

The search for a simple and clean approach toward the production of sulfate radicals for water treatment gave rise to electrochemical and photoelectrochemical activation techniques. The photoelectrochemical activation method does not just distinguish itself as a promising activation method, it is also used as an efficient water treatment method with the ability to treat a myriad of pollutants due to the complementary effects of highly reactive oxidizing species. This perspective highlights some merits that distinguish sulfate monoanion radicals from hydroxyl radicals. It highlights the electrochemical, photoelectrochemical, and in situ photoelectrochemical routes of generating sulfate radicals for advanced oxidation process approach to water treatment. We provide a detailed account of the few known applications of sulfate radical enhanced photoelectrochemical treatments of water laden with organics. Finally, we placed this area of research in perspective by providing outlooks and conclusive remarks.

Managed phreatic zone recharge for irrigation and wastewater treatment

Managed phreatic zone recharge with marginal water, using (existing) drainage systems, raises the water table and increases water availability for crops. This is a newly developed method of freshwater conservation and marginal water treatment and disposal, but risks crop and environmental contamination. The fate of contaminants of emerging concern (CECs) within the irrigated water is addressed. We introduce numerical and analytical models, inspired loosely by a field site where treated domestic wastewater is used for subsurface irrigation. The treated wastewater would otherwise have been discharged into rivers, thereby spreading downstream. Model results show that minimal amounts of CECs are transported to deeper aquifers. Crops are not contaminated, except during dry years where small amounts of mobile CECs rise to the root zone, but then only directly above each irrigation drain. Under an annual precipitation surplus, less-mobile solutes are thus unlikely to ever enter the root zone. The primary mechanism of solute transport is lateral advection within the phreatic aquifer. Despite spatio-temporal heterogeneity in water flux magnitudes and directions, contaminant retardation does not significantly alter mass balance outcomes, only how fast it gets there. Therefore, persistent CECs pose the greatest risks, though overall environmental and crop contamination risks appear low. To maximize complementarity with subsurface irrigation systems, future advances in water treatment technologies should focus on removing persistent CECs. However, the system may be unsuitable for climates with annual precipitation shortages, as CECs may accumulate in the root zone and crops.

Dynamic simulation analysis of city tail water treatment by constructed wetland with biochar substrate.

Constructed wetland (CW) is an important method of ecological water treatment, and CW has obvious advantage in treating low-pollution water. In order to improve the treatment efficiency of CW, the first-order and second-order kinetics simulations of pollutant removal in CW were carried out to optimize operating conditions. The experimental study of city tail water treatment under unmodified biochar (different additions) or different modified biochar conditions showed that the first-order kinetic equation relatively accurately reflect the removal of pollutants by substrate. The relatively optimal range of biochar addition (2.21-3.79%) in the first-order kinetic analysis covered the relatively optimal mass ratio (2.95%). The first-order kinetic equation fitting showed that the half-life of ammonia nitrogen removal by NaOH (0.1 mol·L-1)-modified biochar was reduced by about 10% without plant. The half-life of total phosphorus removal by KMnO4 (0.1 mol·L-1) modified biochar was reduced by about 50%. The half-life of chemical oxygen demand removal by H2SO4 (0.75 mol·L-1) + 8 freeze-thaw cycles modified biochar was reduced by about 9.0%. When the half-life was small, the pollutant removal rate was high. The results of this study further confirmed the effectiveness of the simulation results of pollutant removal in CW with biochar by the first-order kinetic equation. This study further optimized the CW operating conditions and improved the treatment efficiency of nitrogen and phosphorus in the CW.

Diarrheal disease and associations with water access and sanitation in Indigenous Shawi children along the Armanayacu River basin in Peru.

Diarrheal disease, particularly in children under 5 years old, remains a global health challenge due to its high prevalence and chronic health consequences. Public health interventions that reduce diarrheal disease risk include improving access to water, sanitation, and hygiene. Although Peru achieved the 2015 Millennium Development Goal (MDG) indicators for water access, less progress was achieved on sanitation. Furthermore, many Indigenous Peoples were overlooked in the MDG indicators, resulting in a prioritization of Indigenous Peoples in the 2030 Sustainable Development Goals (SDGs). This study aimed to estimate the prevalence of childhood diarrhea, characterize access to water and sanitation, and determine the association of childhood diarrhea with water access and sanitation indicators in 10 Shawi Indigenous communities along the Armanayacu River in the Peruvian Amazon. A cross-sectional survey (n=82) that captured data on diarrheal disease, sociodemographic variables, and water and sanitation exposures was conducted in 10 Shawi communities. Nutritional status of children under 5 was also assessed via physical examination. Descriptive and comparative statistics were conducted. A small proportion (n=7; 8.54%) of participating children reported an episode of diarrhea in the previous month. Almost half (46.30%) of participating children had stunting, wasting, or both. Although not statistically significant, children living in households that used latrines were 4.29 times (95% confidence interval (CI) 1.01-18.19) more likely to report an episode of diarrhea than children living in households that practiced open defecation. Although not statistically significant, children living in households that used water treatment methods were 4.25 times (95%CI 0.54-33.71) more likely to report an episode of diarrhea than children living in households that did not. The prevalence of childhood diarrhea was lower for Shawi than for other Amazon areas. The higher prevalence of childhood diarrhea in households that used latrines and water treatments warrants further investigation into local risk and protective factors. These Shawi communities scored low for the WHO/UNICEF Joint Monitoring Programme indicators for water and sanitation, indicating that they should be prioritized in future water, sanitation, and hygiene initiatives. Research will be required to understand and incorporate local Indigenous values and cultural practices into water, sanitation, and hygiene initiatives to maximize intervention uptake and effectiveness.

The association of arsenic exposure with mortality due to cancer, diabetes, Alzheimer's and congenital anomalies using Poisson regression

The present study aims to determine the relationship between the concentration of arsenic in the groundwater of Hamadan province and the mortality rate due to various types of malignancies, congenital anomalies, diabetes mellitus and Alzheimer's. Mortality data due to various causes of death in Hamadan province were collected for five years (2016–2020). Sampling of drinking water was determined in the reference laboratory using polarography method. Poisson regression was used to investigate the relationship between arsenic level and the death rate due to various types of disease, at a significant level (p value < 0.05). According to the results of Poisson regression, among the various causes of death (N = 8042), Alzheimer's 5.94 (3.67–9.61), diabetes mellitus 4.05 (3.5–5.37), congenital malformations 2.98 (1.88–4.72), breast cancer 2.72 (1.56–4.71), leukemia 1.90 (1.24–2.92), stomach cancer 1.64 (1.28–2.10), Liver cancer 1.58 (1.58–2.30), other digestive organs 5.86 (3.38–10.16), meninges and brain cancer 1.57 (1.02–2.41) showed the highest relationship with arsenic contamination. The results of this study could be evidence for a positive and significant relationship between arsenic concentrations and mortality rates due to cancers, diabetes mellitus, Alzheimer disease, and congenital malformations. Therefore, it's necessary to use appropriate water treatment methods to remove arsenic at the source in contaminated areas.

Natural Organic Matter Removal in Surface Water Treatment via Coagulation—Current Issues, Potential Solutions, and New Findings

Considerable changes have been observed in surface waters’ quality in recent years. They include an increase in dissolved organic carbon (DOC) concentrations, as well as a shift of natural organic matter (NOM) composition in favor of low molecular weight (LMW), and they are expected to occur on a wider scale in the future. Those predictions are particularly worrying given the importance of surface water as the main potable water source for numerous communities across the globe. Conventional methods of surface water treatment for drinking purposes mostly focus on the process of coagulation. The progressing changes in the quality of surface waters, however, render the conventional treatment via coagulation inefficient. The issue of the presence of natural organic matter in drinking water sources, its anticipated changes, and the related treatment problems are all complex and pressing matters that need addressing. This paper aims to provide a critical review of recent findings regarding NOM removal via coagulation in reference to the current NOM-related issues and their potential solutions. The paper discusses the application of different types of coagulants, and their respective advantages and disadvantages. Coagulation-integrated processes including adsorption, membrane filtration, biological processes, and oxidation are also addressed. Lastly, insights on the future approach to the discussed issues and conclusions are presented.

Optimization of effluents using a neural network in the treatment of industrial wastewater

The growth of the planet's population leads to an increase in the problem of access to fresh water. The main sources of water on Earth are brackish and sea water. In connection with the water crisis, water purification becomes an extremely important process, and its achievement is carried out through desalination and various methods of water treatment. In this context, research into the possibility of using neural networks to improve the operation of sewage treatment plants is necessary. The purpose of the research was to optimize and analyze the efficiency of the work of treatment facilities in the treatment of industrial wastewater. Soft computing methods were used to optimize the proposed models. In this study, the exact results of the application of the neural network were determined using analytical and comparative approaches. Treatment of all wastewater and waste generated in the treatment industry involves a number of processes including air flotation, chemical coagulation, settling and biological treatment using fully mixed activated sludge. Various learning functions have been considered, including forward-propagation artificial neural networks (ANNs) such as multilayer perceptron (MLP), cascaded forward-propagation ANNs, and support vector regression (SVR) models. The learning process includes the use of Levenberg-Marquardt optimization algorithms and sequential minimum. The article also provides graphical images illustrating the different types of pollutants, the costs associated with treatment plants, and the color changes in wastewater observed after the treatment process. The obtained results show a high degree of similarity between the predicted and experimental data, which emphasizes the effectiveness of the backpropagation ANN model for accurate predictions. In addition, the integration of machine learning into the production of detergents can be extremely effective in promoting the efficient and sustainable use of water resources. Overall, the paper provides valuable insights into the use of machine learning to address freshwater scarcity

Construction of transfer-free regular through-pore polyimide composite microfiltration membranes via amphiphilic dendron-assisted breath-figure method for water treatment

Regular through-pore membranes exhibit extremely high productivity and size-selective capabilities. Previous studies have demonstrated that the use of a polymer alone on a solid substrate surface hinders the formation of regular through-pore membranes. In this study, amphiphilic dendrons were used as surfactants to concentrate the functional groups and strengthen the weak bonding forces between the molecules, which is conducive to the formation of regular through-pores in the membrane. The amphiphilic dendrons were mixed with commercial-grade polyimide (PI) using chloroform as the solvent, and the solution was evenly coated on the surface of the filter paper. Using the breath-figure method, an ultrathin regular through-pore PI layer was formed directly on the surface of the filter paper. The SEM image shows that regular through-pores were formed only on the surface of the substrate. The preparation process used in this study eliminates the need to transfer ultrathin and weak membranes to the substrate surface, which simplifies the membrane-making process. Pure water and yeast solution filtration tests were conducted on the composite membrane prepared with a 5 mg/ml dendron solution. A pure water permeance of 118,826 L m-2h−1 bar−1 (LMH/bar) was obtained, the yeast solution permeance and rejection are 17,410 LMH/bar and 92.85 %, respectively. The yellow, turbid, muddy water was successfully purified to clean water. The original performance of the fouled membrane was restored after only 30 s of water flushing. This study proposes a new approach to fabricate high-efficiency regular through-pore PI composite microfiltration membranes.

APPLICATIONS AND CHALLENGES OF THE REVERSE OSMOSIS MEMBRANE PROCESS: A REVIEW

Reverse osmosis is one of the most prevalent methods of generating potable water owing to its low power usage, excellent rates of contaminant removal, simple design, large output capacity, and much cheaper initial and maintenance costs than comparable alternatives. In this review, the most important published research related to the reverse osmosis process was reviewed. It was found that the majority of reported studies were related to using the reverse osmosis process for water desalination and wastewater treatment. Research has proven that the reverse osmosis process is a very effective method for desalinating water and treating industrial effluent containing heavy metals, organics, and other pollutants. Fouling was found to be one of the greatest obstacles encountered by the reverse osmosis method in water treatment, which raises operating costs due to the need for frequent cleaning, reduces the membrane's lifespan, and reduces the permeate flux. In general, microfiltration/ultrafiltration pretreatment and backwashing were among the most effective strategies suggested by researchers to reduce fouling and ensure the longevity and proper operation of the system.

Design of Bi4O5Br2/g‐C3N4 heterojunction for efficient photocatalytic removal of persistent organic pollutants from water

AbstractDyes and antibiotics as typical persistent organic pollutants (POPs) are widely present in the environment, but can hardly be removed completely by traditional water treatment methods. Here, we designed Bi4O5Br2/g‐C3N4 composite nanosheets for efficient photocatalytic removal of POPs in water. The Bi4O5Br2/g‐C3N4 composite with a heterojunction structure exhibited high adsorption and photocatalytic activity for removal of tetracycline (TC) and ciprofloxacin (CIP) with excellent cyclic stability, owing to its large specific surface area as well as enhanced charge separation and visible light utilization. Our characterization revealed that h+ and ·OH are responsible for the photocatalytic degradation of TC and CIP. This work provides insights into the design of photocatalytic materials with synergy of adsorption and photocatalytic degradation, and offers a heterojunction construction strategy for addressing the increasingly severe environmental issues.

Recent development in the formation and surface modification of cellulose-bead nanocomposites as adsorbents for water purification: a comprehensive review

Abstract Water pollution is an issue of global concern that demands effective and sustainable solutions through water purification. Adsorption is a popular method for water treatment because it is inexpensive and has a high performance rate. Although commercial activated carbon is the generally preferred adsorbent for adsorption, its widespread use is affected by the high cost and challenges encountered during column adsorption. Biopolymers like cellulose and its derivatives have the potential to replace expensive adsorbents due to their unique characteristics. In recent years, cellulose-bead nanocomposites have gained significant attention as promising adsorbents due to their ability to circumvent the challenges encountered when using powdered adsorbents. To fabricate cellulose beads, cellulose fiber is separated from its source, dissolved in appropriate solvents, shaped into spherical particles and subsequently modified (via esterification, oxidation, crosslinking agents, etc.) to improve its adsorption capacity. This comprehensive review paper presents a detailed analysis of the recent development in the formation and surface modification of 3-D structured cellulose nanocomposites. The outcome of this review on modified cellulose-bead demonstrates their successful fabrication and high adsorption capacities for different contaminants. It is anticipated that cellulose beads, as a bio-adsorbent in industrial settings, will be a low-cost alternative to the more expensive adsorbents shortly.

Synthesis and characterization of an antibacterial nanocomposite derived from two metal-organic frameworks for dye adsorption and antibacterial activity applications

In recent years, humans have been forced to create effective water treatment methods because of the increasing water contamination caused by various industrial activities. This study focuses on synthesizing a nanocomposite consisting of two metal-organic frameworks based on ZIF-8 with effective antibacterial characteristics and water-stable, highly porous UiO-66-NH2. After characterizing the synthesized nanocomposite, its application as (i) an adsorbent for methylene blue (MB) removal from a polluted aqueous environment and (ii) an antibacterial agent; was considered. The impact of different factors on the uptake of MB, including dye concentration, adsorption temperature, and the initial pH of the solution, was studied. When the temperature was raised to 45 °C, the maximum adsorption capacity of UiO-66-NH2 @ZIF-8 for MB improved to 215.78 mg/g. Moreover, the pseudo-second-order model accurately described the experimental MB uptake results. According to the thermodynamic analysis, the spontaneous endothermic adsorption process of MB onto the synthesized UiO-66-NH2 @ZIF-8 was the consequence of an entropy impact instead of an enthalpy change. Additionally, the synthesized nanocomposite exhibited antibacterial efficacy against two different bacteria, gram-negative E. coli and gram-positive S. aureus, with a minimum inhibitory concentration (MIC) of 30 mg/L against both strains. The results indicated that the synthesized MOF@MOF nanocomposite is efficient in dye removal for water treatment and has excellent potential in disinfection applications.

The impact of chlorine, ultraviolet-C, and microwave treatment on the survivability of Blastocystis sp. cysts.

Blastocystis sp. is a common widely distributed gut protozoan, with water transmission identified as one of its transmission routes. This study aimed to investigate the effect of chlorine, ultraviolet (UV)-C, and microwave (MW) treatments on the in vitro viability of cysts of Blastocystis sp. Purified Blastocystis sp. cysts were molecularly subtyped. Viable cysts were subjected to different free chlorine concentrations (1, 2, and 4 ppm), different doses of UV-C (5.13, 10.26, 20.52, and 40.47 mJ/cm2), and MW irradiation times (10, 15, 30, and 45 s). Viability reduction percentage, log10 inactivation, and micrometre-based optical microscopy examined cyst number and appearance after each disinfection trial. The three disinfectants' efficacy and application conditions were assessed. The analysed isolates of Blastocystis cysts were subtype 3, possessed varying sizes and shapes, but two identical genomes. The cysts of Blastocystis sp. were resistant to chlorine at all doses and exposure durations tested. UV-C at a dose of 40 mJ/cm2 and MW treatment for 15 s were able to completely disinfect the cysts. The MW was the most effective disinfectant against Blastocystis cysts based on all evaluated factors. MW irradiation is the most efficient water treatment method for eradicating Blastocystis cysts in an easy and safe manner.

Synergistic enhancement of Ce–ZnO/g-C3N4 photocatalytic performance using N,O-bis-vacancy induction and S-scheme heterojunctions

The photocatalytic decontamination of organic pollutants is an environmentally friendly and efficient water treatment method. The introduction of vacancies, heterojunctions, and doping can enhance the performance of photocatalysts for such applications. In this study, N,O double-vacancy Ce–ZnO/g-C3N4 S-scheme heterojunction photocatalysts were prepared. It is found that the electron separation and transfer efficiencies are considerably improved by the presence of nitrogen vacancies in graphitic carbon nitride (g-C3N4) and oxygen vacancies in ZnO, in addition to the S-scheme heterojunction created between the two materials. In the degradation of methylene blue and ciprofloxacin, the degradation rates exhibited by Ce–ZnO/g-C3N4 are significantly higher than those of the g-C3N4/ZnO system. This remarkable photocatalytic performance of Ce–ZnO/g-C3N4 may result from three key factors: (i) Ce doping, which produces impurity energy levels; (ii) the generation of electron capture centres by the N and O vacancies; and (iii) the synergistic effect of the S-type heterojunction formed at the interface between the two materials. This study therefore provides new approaches for the use of doping, vacancies, and heterojunctions to induce the efficient degradation of organic pollutants.