Sewage Treatment Research Articles

Hydrological simulation scenarios for predicting the future water status of the Niger River in Bamako, Mali, for sustainable development.

The Niger River is critical in providing water for the socio-economic activities and development of Bamako city. However, predicting future water supply and demand is challenging. Therefore, an approach capable of analysing water availability is necessary. This study aims to use the Water Evaluation And Planning (WEAP) software to forecast water availability, treatment scenarios, and the reuse of treated wastewater by 2030. Evaluating the future pollution of the river in Bamako, the simulated flow, Dissolved Oxygen (DO), and Biochemical Oxygen Demand (BOD) along the Niger River from 2017 to 2030 were compared with 2016 values. Notwithstanding the elevated water demand resulting from the accelerated urbanisation and industrialisation, the entire length of the Niger River in Bamako would be contaminated. Even though the water tends to improve downstream, a BOD concentration of 9.83mg/l will exceed the requirement of 5mg/l set by the European Commission's recommendation for surface water quality. The high BOD downstream indicates the river's weakening capacity for self-purification and points to a 0% water demand coverage by 2030. Contrary to irrigation needs, the river cannot be used for domestic purposes due to pollution. Establishing wastewater treatment systems will improve the reuse of treated wastewater and reduce pollution levels in the Niger River by 86%.

Impact and mechanism of polyethylene terephthalate microplastics with different particle sizes on sludge anaerobic digestion.

Municipal wastewater treatment plants (WWTPs) are important sinks for microplastics, and the vast majority of microplastics entering WWTPs are trapped in residual sludge. In order to investigate the effect of microplastics on anaerobic digestion of sludge, polyethylene terephthalate (PET) microplastics with common particle size and physical aging were selected to conduct a comparative study. Regardless of aging, the addition of 300 and 500μm PET microplastics inhibited methane production, with their cumulative methane production reduced by 11.3-24.9% compared to the control group. In contrast, when 100μm microplastics were added, the raw PET promoted methane production, yielding 337L CH4/kg VS, while the aged experimental group showed similar yields to the control group. For the 800μm microplastics treatment group, aged microplastics facilitated methane production while raw microplastics inhibited it, with methane production of 91.0% and 111% of the control group, respectively. The effects were also investigated by model fitting, stage discussion, and microbial community structure analysis. The results discovered that the main rate-limiting steps of adding microplastics with smaller or larger particle sizes (100, 800μm) to methane production were solubilization and hydrolysis, while the main rate-limiting step of microplastics with medium particle sizes (300, 500μm) was methanogenesis. Physically aged PET microplastics with smaller or larger sizes showed a more significant effect on methane production. Furthermore, PET microplastics altered the microbial community structure, shifting methanogens from acetotrophic pathways to hydrotrophic pathways. This study offers new insights into the performance analysis of sludge anaerobic digestion in practical WWTPs.

An estrogenic municipal effluent decreased fathead minnow reproduction to a near stop.

Municipal wastewater treatment plants (WWTPs) release endocrine disrupting chemicals (EDCs) which can impact aquatic species' reproduction (e.g., decrease fecundity). As bioassays can quantify the cumulative effect of mixtures, such as effluents, this study proposes a two-Tier bioassay-based approach to assess EDCs in WWTP effluents. The first Tier is composed of the human receptor transactivation assay for estrogen (hERα) and androgen (hAR), and the Tier 2 comprises an abbreviated 7-day fish short-term reproduction assay (FSTRA; OECD TG 229) in fathead minnow (Pimephales promelas). The approach was assessed on a municipal effluent (12.5, 25 and 50% v/v) and compared to the standard 21-day FSTRA and chemical analysis. The first Tier detected mainly estrogenic activity at 6.7-51.5ng/L of estrogen equivalent (EEQ). The 7-day FSTRA of Tier 2 was able to capture the same arrest in reproduction in the 50% v/v treatment as the 21-day FSTRA. Moreover, around halfway of the 21-day FSTRA, the 12.5% v/v treatment led to a reproduction arrest similarly to the positive control (12.5% v/v+40ng/L of 17α-ethinylestradiol (EE2)). During the 21-day experiment, bisphenols, nonylphenol and 19 pharmaceuticals were detected. Altogether, the results indicate the Tier 1 methodology was robust to identify potential endocrine disruptive activity of the effluent, while the Tier 2 was able to detect reproduction arrest without a clear mechanism of action. Overall, this two-Tier approach provides an initial framework to assess EDCs levels in WWTP effluents, which will help inform on the risk of complex mixtures to protect aquatic ecosystems.

Porous polymers embedded with iron carbon enhanced densified activated sludge formation and wastewater treatment

Municipal wastewater treatment plants in China face significant challenges in effectively removing pollutants from low-strength wastewater with a low carbon-to-nitrogen (COD/N) ratio. This study proposes a novel approach incorporating porous polymers embedded with iron-carbon (PP-IC) into an activated sludge system to enhance treatment. The PP-IC accelerated the formation of densified activated sludge (DAS), characterized by small particle sizes (<200 μm), excellent settleability (sludge volume index: 61 mL/g), and improved pollutant removal efficiency, with total nitrogen and total phosphorus removal rates increasing by 14.4 % and 57.4 %, respectively. DAS formation was achieved within 7 days and stabilized after 42 days. The enrichment of microorganisms, including unclassified_f_Caldilineaceae, Dechloromonas, and Candidatus Accumulibacter, further enhanced pollutant removal. Additionally, Fe2+, Fe3+ and hydroxyl radical (·OH) produced by iron-carbon micro-electrolysis supported DAS formation. Microbial interactions with the iron shavings sustained the long-term stability of the micro-electrolysis process. This synergistic mechanism significantly improved pollutant removal in wastewater treatment.

Mesophilic anaerobic digestion of mixed sludge in CSTR and AnMBR systems: A perspective on microplastics fate.

Most microplastics (MPs) end up in the biosolids produced in wastewater treatment plants (WWTPs) and can pose contamination risks when the biosolids are applied to agriculture. This study evaluated the impact of mesophilic anaerobic digestion on the fate of MPs in WWTP sludge. For this, two laboratory-scale anaerobic digesters were operated in parallel, consisting of a continuous stirred tank reactor (CSTR) and a membrane bioreactor (AnMBR) equipped with an ultrafiltration membrane to decouple the hydraulic and sludge retention times. Both digesters were continuously fed with mixed sludge from a municipal WWTP. The results showed a significant reduction in the MP concentration, with the AnMBR having the higher MP removal efficiency (88.6% vs. 62.1%) and obtaining a higher percentage of biomethanisation (58.3% vs. 43.7%). Polypropylene (PP) and polyacrylonitrile were the main polymers in the mixed sludge, while PP and polyethylene were the dominant polymers in the digested samples. The MP particles in all the samples were predominantly in the 500-104μm size range. Microbiological analysis indicates a greater species diversity in the microbial community of the AnMBR, the results also revealed a symbiotic relationship between the Firmicutes and Patescibacteria phyla in this digester.

Investigating chemical changes, material properties, and off-gas emissions in sewage sludge through thermal plasma treatment.

This study aimed to investigate the thermal plasma treatment of sewage sludge as an alternative waste management solution. Samples were collected from a sewage treatment facility in São Paulo, Brazil, and subjected to thermal treatments in a furnace at temperatures of 400, 600, 800, and 900°C to assess moisture content, mass loss, and ash composition. Subsequently, the samples were processed in a thermal plasma reactor operating at an average power of 30kW. Comprehensive characterization using X-ray fluorescence, X-ray diffraction, and Fourier-transform infrared spectrometry revealed the presence of oxides, particularly those of K, Ca, and Fe, which influence material melting points. Plasma treatment significantly reduced the mass and volume of the sewage sludge, losing up to 72 and 90%, respectively. Gas analysis indicated syngas (CO+H2) production with a high heating value (HHV) of 9049kJ/m³, underscoring the energy recovery potential. Leaching and solubility tests confirmed the treated material as inert and suitable for safe disposal or reuse in construction, with chemical and structural analyses showing that the vitrified material was primarily composed of SiO₂. These findings highlight the effectiveness of thermal plasma treatment in achieving sustainable sewage sludge management by combining waste reduction, energy recovery, and the production of environmentally safe by-products.

Enhanced Phthalate Degradation in Sewage Plant by Heterogeneous Electro-Fenton modifiedd bimetallic Single-Atom Catalyst

Enhanced Phthalate Degradation in Sewage Plant by Heterogeneous Electro-Fenton modifiedd bimetallic Single-Atom Catalyst

Full-scale application and performance of circulated biological and constructed wetland system for batik wastewater treatment

Full-scale application and performance of circulated biological and constructed wetland system for batik wastewater treatment

Hybrid constructed wetlands for tertiary treatment of poultry slaughter wastewater to meet quality standards of discharge and reuse: a full-scale case study in Vietnam.

The construction and operation of a small-scale hybrid constructed wetland (HCW) system for tertiary wastewater treatment was presented. The HCW system includes a vertical sub-surface flow CW (VFCW), a horizontal sub-surface flow CW (HFCW), and a free water surface flow CW (FWSCW). Operated in series, it had a total area of 150 m2. It received 7.5 m3day of secondary effluent wastewater from the existing treatment system of a poultry slaughter enterprise at the production capacity of 500 ducks per day in an on-site experiment of 12months. The results showed that the removal efficiencies of biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), ammonia nitrogen (NH4+-N), nitrate nitrogen (NO3--N), total nitrogen (TN), orthophosphate (PO43--P), total phosphorus (TP), Escherichia coli (E. coli), and total coliforms (T. coli) reached average values of 76.2, 78.7, 77.1, 83.9, 86.3, 84.9, 72.3, 73.9, 98.9, and 96.4%, respectively, while the effluent concentrations of the study system complied with the most difficult limits not only for discharge into the receiving water source but also for reusing wastewater to water plants. The function made by various configurations such as a VFCW, a HFCW, and a FWSCW placed sequentially in the HCW system proved crucial to treat wastewater and make it reusable.

Phosphorus recovery and solid waste reutilization by synergistic treatment of BOF slag and sewage sludge incinerated ash

Phosphorus recovery and solid waste reutilization by synergistic treatment of BOF slag and sewage sludge incinerated ash

Effects of degradable and non-degradable microplastics on SPNEDPR-AGS system: Sludge characteristics, nutrient transformation, key enzyme, and microbial community

The environmental risk of microplastics (MPs) in aerobic granular sludge (AGS) system is unclear. This study evaluates the effects of non-biodegradable polyvinyl chloride microplastics (PVC-MPs) and biodegradable polylactic acid microplastics (PLA-MPs) on AGS systems. The results showed that both destroyed the performance of AGS systems, with PVC-MPs achieving this by disrupting the AGS structure, while PLA-MPs mainly by causing the expansion of filamentous bacteria induced through the stimulation by lactic acid metabolite (R0: 5.52 ± 0.49 μg/L; RPLA5: 11.67 ± 0.56 μg/L). Moreover, both MPs inhibited nitrogen removal by disrupting partial nitrification and endogenous denitrification and suppressed key microbes such as Candidatus Competibacter and Nitrosomonas. Metabolic pathway analysis and molecular docking have further confirmed the mechanisms by which MPs affect critical metabolic pathways and key enzymes. Consequently, the hazards of biodegradable MPs to the stable operation of sewage treatment plants should also be of concern.

Nutrient removal performance and microbial community analysis in an integrated wastewater treatment system with macroalgae (U. meridionalis) and Bacillus

Nutrient removal performance and microbial community analysis in an integrated wastewater treatment system with macroalgae (U. meridionalis) and Bacillus

Effects of multiple temperature variations on nitrogen removal and microbial community structure in tidal flow constructed wetlands.

Tidal-flow constructed wetlands (TFCWs) provide distinct advantages for nitrogen removal by enhancing microbial activity through dynamic water level fluctuations. However, effects of temperature on nitrogen transformation processes and microbial community dynamics in TFCWs remain unclear. We analyzed the effects of TFCWs on nitrogen transformation and microbial community structure under different temperature conditions (23, 16, 12, and 8 °C) through 140 days of temperature-controlled experiments. The nitrogen removal efficiency was considerably enhanced at 23 °C, with transformation rates for ammonia nitrogen (NH4+-N) and total nitrogen (TN) reaching 9.28 ± 0.06 g/m³/day and 8.35 ± 0.08 g/m³/day, respectively. Conversely, at 8 °C, the nitrogen removal efficiency declined, with NH4+-N and TN transformation rates decreasing to 7.38 ± 0.05 g/m³/day and 6.78 ± 0.05 g/m³/day, respectively. Temperature markedly influenced the microbial diversity and community structure, as evidenced by the considerably higher Shannon diversity indices for bacterial communities at 23 °C (5.12 ± 0.21) compared with those at 8 °C (4.52 ± 0.40). Positive microbial interactions were more prevalent at lower temperatures (12 and 8 °C), leading to stronger symbiotic relationships, although the network complexity diminished. The microbial community composition of taxa such as Firmicutes, Proteobacteria, and Thaumarchaeota exhibited greater resilience at lower temperatures. Changes in dissolved oxygen levels also drove changes in bacterial and archaeal communities. These findings underscore the pivotal role of temperature in regulating ecological function and nitrogen removal efficiency of TFCWs and highlight the importance of accounting for temperature variations in the design and management of wastewater treatment systems.

Physiological and biochemical responses of Phragmites australis correlate with water quality in lagoon wastewater treatment system

Physiological and biochemical responses of Phragmites australis correlate with water quality in lagoon wastewater treatment system

Microalgae - bacteria based wastewater treatment systems: Granulation, influence factors and pollutants removal.

Wastewater treatment based on microalgae and bacteria symbiosis is an environmentally friendly, sustainable technology that has attracted attention recently because of its high efficiency in treating pollutants, saving energy, and short-term biomass recovery. Among them, the granular microalgae and bacteria combination emerges with the advantages of rapid gravity settling, good resistance to adverse environmental conditions, outstanding wastewater treatment performance, and easy biomass recovery. This review aims to clarify the microalgal-bacterial granule (MBG) - based process for wastewater treatment. In particular, MBG characteristics, granulation mechanism, and influence factors on the process are also discussed. The review contributes to the knowledge system related to MBG research in recent years, thereby pointing out research gaps that need to be filled in the future.

Sewage pollution from onsite sewage disposal systems and an offshore wastewater treatment plant outfall in coastal waters of Keaukaha, Hawaiʻi Island

Sewage pollution from onsite sewage disposal systems and an offshore wastewater treatment plant outfall in coastal waters of Keaukaha, Hawaiʻi Island

BCQDs enhanced Bi-based photocatalysts for dye degradation and visual sewage treatment

BCQDs enhanced Bi-based photocatalysts for dye degradation and visual sewage treatment

Treatment of compound pollution in simulated livestock and poultry wastewater by algae-bacteria symbiosis system.

Livestock and poultry breeding wastewater contains a large number of heavy metals and antibiotics; the volume is huge, and it is difficult to treat, which causes serious pollution of the environment. Some studies have shown that symbiotic systems can effectively improve the efficiency of sewage treatment, but there is still a lack of research on the treatment of livestock and poultry wastewater. This experiment not only provides a more in-depth discussion of previous studies, but also demonstrates the feasibility of symbiotic treatment of livestock and poultry wastewater and explores the survival mode and operation mechanism of algal and bacterial symbiosis. The results show that the presence of bacteria greatly promoted the growth of microalgae, with production of 0.50-0.59g/L biomass and 17.5% lipid content. Lipid levels in the algae from the symbiotic system were 1.3 times higher than for the system of pure algae, which is attributed to the bacteria releasing extracellular substances to promote their own growth and providing small molecules of organic matter and other essential elements which can be used by microalgae. In addition, during the removal of complex pollutants in the symbiotic system we found that the main contributor to the removal of heavy metal ions was the adsorption by Chlorella, while the decomposition of antibiotics mainly originated from bacteria. Furthermore, in the context of this experiment was obtained the highest removal rate of SM2 reached 28.8%, while the removal rate of Cu(II) reached 60.6%-66.7%. The technology of symbiotic treatment of wastewater from livestock and poultry breeding fills a gap and lays a theoretical foundation for the improvement of wastewater treatment.

Encapsulation of bio-wasted derived persimmon peel extract in loaded polyvinyl alcohol/gelatin aerogel for enhanced inactivation of pathogenic bacteria in domestic sewage treatment

Encapsulation of bio-wasted derived persimmon peel extract in loaded polyvinyl alcohol/gelatin aerogel for enhanced inactivation of pathogenic bacteria in domestic sewage treatment

Pollutants degradation performance and microbial response evaluation about expressway service area sewage treatment of continuous flow anoxic-oxic moving bed biofilm reactor system

Pollutants degradation performance and microbial response evaluation about expressway service area sewage treatment of continuous flow anoxic-oxic moving bed biofilm reactor system