Wastewater Discharge Research Articles

Towards sustainable water management for Galdieria sulphuraria cultivation

The red microalga Galdieria sulphuraria has emerged as a promising biotechnological platform for large-scale cultivation and production of high-value compounds, such as the blue pigment phycocyanin. However, a large amount of freshwater and a substantial supply of nutrients challenge both the environmental and the economic sustainability of algal cultivation. Additionally, the extremophilic nature of Galdieria sulphuraria requires cultivation in an acidic culture medium that directly leads to strongly acidic wastewater, which in turn generally exceeds legal limits for industrial wastewater discharge. This research aims to address these challenges, by investigating cultivation water reuse as a strategy to reduce the impacts of Galdieria sulphuraria management. The results indicated that a 25 % water reuse may be easily implemented and showed to be effective at the pilot scale, providing no significant changes in microalgae growth (biomass productivity ~0.21 g L−1 d−1) or in phycocyanin accumulation (~ 10.8 % w/w) after three consecutive cultivation cycles in reused water. Moreover, a single cultivation cycle with water reuse percentages of 71 and 98 %, achieved with membrane filtration and with centrifugation, respectively, was also successful (biomass productivity ~0.24 g L−1 d−1). These findings encourage freshwater reuse implementations in the microalgae sector and support further investigations focusing on coupling cultivation and harvesting in continuous, real-scale configurations. Centrifugation and membrane filtration required substantially different specific electrical energy consumption for water reuse and biomass concentration: in real applications, the former technique would roughly span from 1 to 10 kWh m−3 while the latter is expected to fall within the ample range 0.1–100 kWh m−3, strongly dependent on system size. For this reason, the most suitable separation train should be chosen on a case-by-case basis, considering the prevailing flow rate and the target biomass concentration factor targeted by the separation process.

Implications of Water Quality Index and Multivariate Statistics for Improved Environmental Regulation in the Irtysh River Basin (Kazakhstan)

The selection of sites for permanent environmental monitoring of natural water bodies should rely on corresponding source apportionment studies. Tools like the water quality index (WQI) assessment may support this objective. This study aims to analyze a decade-long dataset of measurements of 26 chemical components at 26 observation points within the Irtysh River Basin, aiming to identify priority zones for stricter environmental regulations. It was achieved through the WQI tool integrated with geoinformation systems (GISs) and multivariate statistical techniques. The findings highlighted that both upstream sections of tributaries (Oba and Bukhtarma rivers) and the mainstream of the basin are generally in good condition, with slight fluctuations observed during flooding periods. Areas in the basin experiencing significant impacts from mining and domestic wastewater treatment activities were identified. The rivers Glubochanka (GL) and Krasnoyarka (KR) consistently experienced marginal water quality throughout the observation period. Various contaminant sources were found to influence water quality. The impact of domestic wastewater treatment facilities was represented by twofold elevated concentrations of chemical oxygen demand, reaching 22.6 and 27.1 mg/L for the KR and GL rivers, respectively. Natural factors were indicated by consistent slight exceedings of recommended calcium levels at the KR and GL rivers. These exceedances were most pronounced during the cold seasons, with an average value equal to 96 mg/L. Mining operations introduced extremal concentrations of trace elements like copper, reaching 0.046–0.051 mg/L, which is higher than the threshold by 12–13 times; zinc, which peaked at 1.57–2.96 mg/L, exceeding the set limit by almost 50–100 times; and cadmium, peaking at levels surpassing 1000 times the safe limit, reaching 0.8 mg/L. The adverse impact of mining activities was evident in the Tikhaya, Ulba, and Breksa rivers, showing similar trends in trace element concentrations. Seasonal effects were also investigated. Ice cover formation during cold seasons led to oxygen depletion and the exclusion of pollutants into the stream when ice melted, worsening water quality. Conversely, flooding events led to contaminant dilution, partially improving the WQI during flood seasons. Principal component analysis and hierarchical cluster analysis indicated that local natural processes, mining activities, and domestic wastewater discharge were the predominant influences on water quality within the study area. These findings can serve as a basis for enhanced environmental regulation in light of updated ecological legislation in Kazakhstan, advocating for the establishment of a comprehensive monitoring network and the reinforcement of requirements governing contaminating activities.

Behaviour of dissolved inorganic salts in the cooling water of a nuclear power plant open recirculation system and formation of water discharge.

The main problem in the operation of nuclear power plants (NPPs) is the scale formation of mineral impurities in an open recirculating system (ORS). The discharge of water from an ORS into natural water bodies can alter the chemical equilibrium of wastewater components, necessitating continuous monitoring. The purpose of this study was to analyse the behaviour of dissolved inorganic salts (DIS) in water within an ORS during water treatment, using the Rivne Nuclear Power Plant (RNPP) as a case study. Moreover, the analysis impact of their discharge with return water in the Styr River. The DIS concentration has a significant impact on the efficiency of the system and the environmental of an ORS power plant. Altogether, each of the DIS components was analysed separately using the standard measurement methods, statistical methods of data processing and correlation analysis. In addition, the annual discharge of the DIS components was calculated, and the amount of discharge was assessed for compliance with the maximum discharge limit. Thus, the impact of the formation of DIS and the variations in their concentration levels upon the discharge of wastewater into a natural water body were examined.

Innovative indenone-derivative colorimetric fluorescent probe: A approach for copper ion detection in water.

Copper (Cu2+) is a metal chemical element closely related to human life and is widely used in many fields. However, with the discharge of copper wastewater, the water quality will be seriously affected, leading to excessive intake of Cu2+ and a variety of diseases. Hence, there is a pressing need for an effective detection method for Cu2+ in aqueous environments. Leveraging the remarkable attributes of GFP chromophores and indenone derivatives, we have created a novel colorimetric fluorescent probe P-Cu2+, tailored for efficient copper ion detection. The addition of Cu2+ causes the solution to visibly change from colorless to a pronounced yellow, enabling naked-eye detection and offering promise for real sample analysis.

Deciphering the ecological impact of azo dye pollution through microbial community analysis in water-sediment microcosms.

The uncontrolled release of untreated dyeing wastewater into aquatic ecosystems poses global environmental risks. It alters native microbial communities and associated ecological processes, often going unnoticed. Therefore, the influence of acid orange 7dye (AO7) contamination on the natural microbial community was investigated using a water-sediment microcosm. Compared to sterile microcosms, complete dye decolourization in natural microcosms showed microbial communities' significance in combating xenobiotic contamination. Proteobacteria dominated the water community, whereas Firmicutes dominated the sediment. AO7 exposure induced notable shifts in the structural composition of the bacterial community in both water and sediment. Niveispirillum exhibited a marked decrease, and Pseudomonas demonstrated a notable increase. The - 9.0 log2FC in Niveispirillum, a nitrogen-fixing bacterium, from 24.4% in the control to 0.1% post-treatment, may disrupt nutrient balance, plant growth, and ecosystem productivity. Conversely, elevated levels of Pseudomonas sp. resulting from azo dye exposure demonstrate its ability to tolerate and bioremediate organic pollutants, highlighting its resilience. Functional profiling via KEGG pathway analysis revealed differential expression patterns under AO7 stress. Specifically, valine, leucine, and isoleucine degradation pathways in water decreased by 52.2%, and cysteine and methionine metabolism ceased expression entirely, indicating reduced protein metabolism and nutrient bioavailability under dye exposure. Furthermore, in sediment, glutathione metabolism ceased, indicating increased oxidative stress following AO7 infusion. However, C5-branched dibasic acid metabolism and limonene and pinene degradation were uniquely expressed in sediment. Decreased methane metabolism exacerbates the effects of global warming on aquatic ecosystems. Further, ceased-butanoate metabolic pathways reflect the textile dye wastewater-induced adverse impact on ecological processes, such as organic matter decomposition, energy flow, nutrient cycling, and community dynamics that help maintain self-purification and ecological balance in river ecosystems. These findings underscore the critical need for more comprehensive environmental monitoring and management strategies to mitigate ecological risks posed by textile dyes in aquatic ecosystems, which remain unnoticed.

Environmentally friendly non-saponification solvent extraction and separation process for RE(III) (RE = Eu, Gd and Tb) in acetic acid solution using HEHEHP/n-heptane

The key to achieving sustainable metal extraction development is to avoid the generation of high-salt wastewater from the source. Here, a new system for the extraction and separation of lanthanide elements Eu(III), Gd(III) and Tb(III) from the acetic acid solution using HEHEHP (2-ethylhexyl hydrogen-2-ethylhexylphosphonate) was studied. The corresponding parameters including contact time, HEHEHP concentration, concentrations of rare earth metal ions and acetic acid in the initial solution, aqueous/organic phase volume ratio (R(A/O)), and temperature were considered to optimize the conditions for the separation of different rare earth elements. The results showed that the separation coefficients of Tb(III)/Gd(III) and Gd(III)/Eu(III) in the acetic acid system were approximately 6.2 and 1.7, with HEHEHP of 0.15 mol/L and R(A/O) of 2:1, and the extraction efficiency of RE(III) reached approximately 73.1%, which was higher than that in the hydrochloric acid and sulfuric acid systems. The mechanism associated with the extraction reaction was evaluated and discussed by the maximum loading capacity method, chromatographic analysis, and FT-IR spectrometric analysis. The mechanism followed a cation exchange reaction and acetic acid did not participate in the extraction process. The feasibility of the separation of Tb(III) from Eu(III) and Gd(III)was also given in terms of the separation coefficients between different elements at different extraction conditions. Since saponification is not necessary in the acetic acid extraction system, it can considerably reduce wastewater discharge to the ecological environment from the source.

A novel nanofiltration membrane with a dual-charged layer to simultaneously remove anions and cations from acid mine drainage

A novel nanofiltration (NF) membrane with a positively and negatively dual-charged layer was finely designed in this study. The membrane was prepared by co-deposition of 4-tert-butylpyrocatechol (TBC) and polyethyleneimine (PEI) and electrostatic interaction to assemble positively and negatively charged functional layers on a substrate which is polyamide (PA)-based NF membrane. The NF membrane achieved excellent retention capacity through the combined effects of Donnan repulsion and electrostatic field trapping. The prepared membrane had a dense but thin surface layer with an average pore size of 0.84 nm, enabling an improved membrane flux of 8.66 L/(m2·h·bar) and high rejection to divalent inorganic salt ions (93.56 % Mg2+, 99.56 % SO42-). The membrane was used to treat acid mine drainage (AMD) and achieved an excellent retention capacity for ions in AMD (93.25 % Mg2+, 91.58 % Ca2+, 94.22 % Mn2+, 95.96 % SO42-), meeting industrial wastewater discharge standards. In addition, the NF membrane demonstrated good anti-fouling performance during the AMD treatment and significant potential for environmental remediation applications.

Situbondo communal waste management study: application of the anaerobic baffled reactor method at the Salafiyah Syafi'iyah Islamic boarding school

Background : This study examines the planning of a communal wastewater treatment plant (IPAL) at the Salafiyah Syafi'iyah Islamic Boarding School, Situbondo Regency, using the Anaerobic Baffled Reactor (ABR) method. Methods: This study uses the ABR method supported by literature studies as the basis for the preparation of the writing. The study also involved observation and field observation. Findings: (1) the domestic wastewater discharge generated by 4,410 people or 74 rooms is 364,408 m³/day, while the non-domestic wastewater discharge is 0.20 m³/day, bringing the total wastewater discharge to 364,608 m³/day. (2) The ABR method was chosen because it has several advantages, such as relatively small land requirements, ease of construction, operation and maintenance, no need for electrical energy, and more efficient costs. (3) The dimensions of each ABR compartment were designed to be 11.4 m long, 2.3 m wide, and 2.6 m high, which ensures even distribution of wastewater and effective treatment. Conclusion: The three research results led to the author's understanding that the ABR method is a suitable and efficient solution for wastewater treatment at Salafiyah Syafi'iyah Islamic Boarding School. For further planning, it is recommended to conduct detailed calculations regarding the Wastewater Management System (WMS) and consider the use of alternative methods such as Constructed Wetland or Anaerobic Filter Reactor, especially considering the area of the pesantren which is surrounded by rice fields. Novelty/Originality of this study: This study offers an innovative solution for wastewater treatment in Islamic boarding school environments by applying the Anaerobic Baffled Reactor (ABR) method. This study not only designs an efficient and cost-effective system but also considers the specific context of Islamic boarding schools, paving the way for applying environmentally friendly technologies in Islamic educational institutions.

Pollution Assessment of the Tigris River Sediments Resulting from Wastewater Discharge in Baghdad, Iraq

This study aimed to study the concentrations of some trace elements, such as Pb, Ni, Cd, Cu, Cr, Zn, Mn, and Fe and evaluate the level of pollution resulting from sewage on the Tigris River sediment by selecting eight stations distributed along the River (Central bank of Iraq, Jadriya Bridge, Al-Dora (Al-Dora silo), Sinak Bridge, Ahrar bridge, River street, Medical city, Al-Kadhimiya) in Baghdad City. The study was conducted during two seasons, winter and summer. Geochemical pollution indices such as geoaccumulation factor and contamination factor were used to evaluate the degree of acidity of river sediment. The results showed that the summer season of the Tigris River recorded relatively higher concentrations than the winter season. This may be because of the decrease in the dilution factor of these elements in the sediment due to the low water levels during the summer. According to the I-geo results, the sixth site's sediment is unpolluted with Fe, Mn, Cr, Ni, Zn, Pb, and Cd in both seasons and mildly polluted with Cu in the summer. The Cu contamination factor, classified as class 3, indicates significant contamination to severely pollute in summer, while Fe, Pb, Cu, and Zn conbankred unpolluted in both seasons. Fe, Mn, Cr, Ni, Pb, Cd, and Zn are not polluted in any season. However, Cu's contamination factor is classified as class 3, meaning significant contamination occurs during summer.

Assessment of environmental impacts from authorized discharges of tritiated water from the Fukushima site to coastal and offshore regions

In August 2023, the long-planned discharging of radioactive wastewater from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) started after the confirmation of its feasibility and safety. As this water contains elevated amounts of tritium even after being diluted, a lot of resources have been invested in the monitoring of the Fukushima coastal region where the discharge outlet is located. We compare the first 3H surface activity concentrations from these measurements (up to the end of November 2023) with the available background values to evaluate a possible impact of the long-term discharging on humans and environmental levels of the radionuclide of interest in the same or nearby area. From our results, we can conclude that the joint effect of horizontal and vertical mixing has been significant enough to reduce tritium concentrations at the monitored locations in the region close to the FDNPP port two days after the end of the respective phase of the discharging beyond the detection limit of the applied analytical methods (∼0.3 Bq L−1) which is by five orders of magnitude lower than safety limit for drinking water set by the World Health Organization (WHO). Moreover, the distant correlation analysis showed that tritium concentrations at stations located further than 1.4 km were very close to pre-discharge levels (∼0.4 Bq L−1). We also estimated that the 3H activity concentration in the offshore Fukushima region would be elevated by 0.01 Bq L−1 at maximum over a year of continuous discharging, which is in concordance with the already published modeling papers and much less than the impact of the FDNPP accident in 2011.

Wastewater Discharge Transports Riverine Microplastics over Long Distances.

Wastewater discharge from wastewater treatment plants continuously pumps microplastics into rivers, yet their transport distances within these waterways remain unknown. Herein, we developed a conceptual framework by synthesizing the microplastic data from the Yangtze River Basin to evaluate its transport distances, quantifying a significant spatial dependence between large-scale wastewater discharge and riverine microplastics (p < 0.05). The presence of microplastics at a specific sampling site could be attributed to wastewater discharge within a large-scale range spanning >1000 km upstream, encompassing a substantial portion equivalent to one-third of the Yangtze River Basin. The dominance analysis indicated that the contribution of wastewater discharge in rivers with higher discharge (>100 m3/s) to riverine microplastic pollution exceeded 65% within the Yangtze River Basin. The spatial dependence framework of riverine microplastics on wastewater discharge advances our prior understanding of the prevention and control of riverine microplastics by demonstrating that such pollution is not limited to nearby environmental factors.

On-Site Inactivation for Disinfection of Antibiotic-Resistant Bacteria in Hospital Effluent by UV and UV-LED.

The problem of antimicrobial resistance (AMR) is not limited to the medical field but is also becoming prevalent on a global scale in the environmental field. Environmental water pollution caused by the discharge of wastewater into aquatic environments has caused concern in the context of the sustainable development of modern society. However, there have been few studies focused on the treatment of hospital wastewater, and the potential consequences of this remain unknown. This study evaluated the efficacy of the inactivation of antimicrobial-resistant bacteria (AMRB) and antimicrobial resistance genes (AMRGs) in model wastewater treatment plant (WWTP) wastewater and hospital effluent based on direct ultraviolet (UV) light irradiation provided by a conventional mercury lamp with a peak wavelength of 254 nm and an ultraviolet light-emitting diode (UV-LED) with a peak emission of 280 nm under test conditions in which the irradiance of both was adjusted to the same intensity. The overall results indicated that both UV- and UV-LED-mediated disinfection effectively inactivated the AMRB in both wastewater types (>99.9% after 1-3 min of UV and 3 min of UV-LED treatment). Additionally, AMRGs were also removed (0.2-1.4 log10 for UV 254 nm and 0.1-1.3 log10 for UV 280 nm), and notably, there was no statistically significant decrease (p < 0.05) in the AMRGs between the UV and UV-LED treatments. The results of this study highlight the importance of utilizing a local inactivation treatment directly for wastewater generated by a hospital prior to its flow into a WWTP as sewage. Although additional disinfection treatment at the WWTP is likely necessary to remove the entire quantity of AMRB and AMRGs, the present study contributes to a significant reduction in the loads of WWTP and urgent prevention of the spread of infectious diseases, thus alleviating the potential threat to the environment and human health risks associated with AMR problems.

Salinity responsive mechanisms of sulfur-based mixotrophic denitrification and ectoine induced tolerance enhancement

Increasing discharge of saline wastewater poses a challenge for heterotrophic and sulfur autotrophic denitrification (HSAD) in nitrogen removal. This study explored the response mechanism of mixotrophic denitrifying microorganisms to high-salt stress and feasible mitigation strategies. Results showed that denitrification efficiency was promoted at 2 % salinity but significantly decreased at 6 %, with NO3–-N removal rate decreased from 95.77 % to 38.01 %. The contribution of sulfur autotrophic denitrification (SAD) remained higher than heterotrophic denitrification (HD). High salinity stimulation led to an increase in reactive oxygen species (ROS) content, while the nicotinamide adenine dinucleotide (NADH) content, adenosine triphosphate (ATP) level, and electron transport system activity (ETSA) decreased by 10.74 %, 46.6 % and 56.28 % at 6 % salinity, respectively. Additionally, high salt inhibited the activity of nitrate reductase (NAR) and nitrite reductase (NIR), reducing the abundance of denitrifying bacteria. Notably, the addition of 250 mg/L of ectoine at 6 % salinity alleviated stress, promoted the secretion of extracellular polymeric substances (EPS) to protect the microorganisms, reduced microbial oxidative stress, and maintained metabolic and denitrification enzyme activities. Ectoine acted as an osmotic pressure regulator and protective agent, maintaining intracellular enzymes and macromolecular structure, thus enhancing denitrification efficiency. Microbial community analysis demonstrated a 3.99 % increase in HD functional bacteria abundance with ectoine addition, highlighting its crucial role in regulation community succession and stability. Structural equations modeling analysis identified the regulatory relationship paths involved in the response and mitigation of HSAD to high salinity stress. This study deepens understanding of the inhibition mechanism of HSAD caused by high-salt wastewater and provides a feasible technical solution for salt stress alleviation in sulfur-based mixotrophic denitrification.

Hydro-chemical characteristics of Biring and Tangting Rivers (Nepal) and evaluation of water quality for drinking and irrigation purposes

Although river water is vital for drinking, irrigation and domestic needs, it faces threats from natural processes and human activities. Small and medium-sized rivers, especially in Nepal, remain understudied despite their vital importance in providing water to densely populated areas. This study evaluated the suitability for drinking and irrigation and the hydro-chemical characteristics of the Biring and Tangting rivers in Koshi province, Nepal. The results showed that turbidity, pH, EC, TDS, TH, NH4+, K+, Ca2+, Mg2+, Na+, Cl−, SO42−, HCO3− and NO3− values of all sampling sites in the Biring and Tangting rivers, except for the turbidity value of 10.39 NTU recorded in the PT9 site of the Tangting River, did not exceed maximum limit values set for drinking water. However, according to Water Quality Index results, the water of both rivers was in poor condition for drinking due to domestic wastewater discharges and cremation activities which caused high NH4+ levels. The major cations in both rivers were listed as Ca2⁺ > Na⁺ > K⁺ > Mg2⁺, while the major anions were listed as HCO₃⁻ > Cl⁻ > SO₄2⁻ > NO₃⁻. Gibbs and Piper diagrams showed that geogenic weathering of carbonate rocks prevailing in the region affected the hydrochemistry in both rivers. Evaluation based on seven different irrigation indices and US salinity laboratory diagram revealed that the water of both rivers was suitable for irrigation despite some magnesium-related limitations.

Risk Factors of Mariculture Supply Chain Based on Green Development: A Case Study of Changhai County in China

China is a global leader in aquaculture, and mariculture has become an important part of Chinese agriculture and one of the important growth points of the rural economy. However, environmental changes and industrial restructuring have brought new risks to the aquaculture supply chain. Recently, people have also paid more and more attention to the marine environment because a good marine environment is the foundation of the healthy development of mariculture. This study analyses the risks in the aquaculture supply chain from the perspective of the marine environment, using Changhai County, Liaoning Province, as an example. The study identified marine environmental issues such as over-sized aquaculture, irrational aquaculture structure, resource integration gaps, nuclear wastewater discharge and offshore oil pollution. Recommendations included restructuring aquaculture, professional training, establishing cooperative mechanisms, and improving seafood quality testing and marine environment monitoring. Addressing these challenges is essential to ensure the stable and healthy development of seafood markets and the sustainability of the aquaculture industry.

Incentive mechanism for allocating wastewater discharge responsibility based on cooperative game theory

Clarifying responsibility for wastewater discharges and enhancing reasonable allocation of wastewater emission permits are critical for controlling wastewater discharge in the context global sustainable development plans. The traditional wastewater allocation approach has several drawbacks, such as sub-regional "free-riding," imbalanced regional development and demand, and unfair allocation mechanism. This study developed a model based on cooperative game theory to allocate responsibility for wastewater discharge in China's Tuojiang River Basin. In this model, the level of impact of a watershed sub-region on the water environment is determined, according to which the wastewater discharge responsibility is assigned. The stronger the impact of upstream sub-regions on downstream wastewater discharge, the greater the responsibility for wastewater discharge. Furthermore, by implementing the wastewater cooperation model, sub-regions can monitor and incentivize each other, through which wastewater discharges can be reduced by 16.38%, compared to the baseline mechanism and overall discharges can be reduced by 5007.99 tons. This study provides recommendations for appropriate management authorities to improve the allocation of wastewater discharge responsibility at the watershed scale.

A Comparative Analysis of Chinese and American News Discourse Based on Appraisal Theory

This paper takes news reports about Fukushima nuclear wastewater discharge from China Daily and Washington Post as the research corpus, conducts a comparative analysis on the corpus from three subsystems of appraisal theory including attitude, engagement and graduation, then statistically analyzes the use of appraisal resources in the discourses and their distributional characteristics to explore attitudes and stances of the Chinese and American media towards Japanese wastewater nuclear discharge. The results show that the overall distribution of appraisal resources in China Daily and Washington Post is comparable and the difference in the frequency of using attitude resource is not significant, but the uses of engagement resources and graduation resources in China Daily are higher than those in Washington Post.

Deep-sea microorganisms-driven V5+ and Cd2+ removal from vanadium smelting wastewater: Bacterial screening, performance and mechanism

The disorderly discharge of industrial wastewater containing heavy metals has caused serious water pollution and ecological environmental risks, ultimately threatening human life and health. Biological treatment methods have obvious advantages, but the existing microorganisms exhibit issues such as poor resistance, adaptability, colonization ability, and low activity. However, a wide variety of microorganisms in deep-sea hydrothermal vent areas are tolerant to heavy metals, possessing the potential for efficient treatment of heavy metal wastewater. Based on this, the study obtained a group of deep-sea microbial communities dominated by Burkholderia-Caballeronia-Paraburkholderia through shake flask experiments from the sediments of deep-sea hydrothermal vents, which can simultaneously achieve the synchronous removal of vanadium and cadmium heavy metals through bioreduction, biosorption, and biomineralization. Through SEM-EDS, XRD, XPS, and FT-IR analyses, it was found that V(V) was reduced to V(IV) through a reduction process and subsequently precipitated. Glucose oxidation accelerated this process. Cd(II) underwent biomineralization to form precipitates such as cadmium hydroxide and cadmium carbonate. Functional groups on the microbial cell surface, such as -CH2, C=O, N-H, -COOH, phosphate groups, amino groups, and M-O moieties, participated in the bioadsorption processes of V(V) and Cd(II) heavy metals. Under optimal conditions, namely a temperature of 40 °C, pH value of 7.5, inoculation amount of 10%, salinity of 4%, COD concentration of 600 mg/L, V5+ concentration of 300 mg/L, and Cd2+ concentration of 40 mg/L, the OD600 can reach its highest at 72 h, with the removal efficiency of V5+, Cd2+, and COD in simulated vanadium smelting wastewater reaching 86.32%, 59.13%, and 61.63%, respectively. This study provides theoretical insights and practical evidence for understanding the dynamic changes in microbial community structure under heavy metal stress, as well as the resistance mechanisms of microbial treatment of industrial heavy metal wastewater.

Wastewater as a nutrient source for hydroponic production of lettuce: Summer and winter growth

Solutions combining soilless cropping systems with wastewater reuse can offer benefits in the agriculture sector, reducing pressure on water resources, promoting sustainable production, and reclaiming wastewater. However, assessing the sanitary risks associated with wastewater reuse is of utmost importance. This study aimed to investigate the hydroponic growth of lettuce (Lactuca sativa var. crispa L.) in wastewater from an urban treatment plant with different levels of treatment and evaluate potential sanitary risks. Crop growth took place in a greenhouse, during summer and winter periods, using wastewater after primary (PTW) or secondary (STW) treatment, and a nutrient solution (NS), as control. Physical and chemical water quality parameters, morphological crop growth parameters, and environmental conditions inside the greenhouse were monitored. Toxicity analyses were carried out through cell viability assays with the Caco-2 cell line and total coliforms and Escherichia coli (E. coli) were determined. Wastewater-grown plants achieved acceptable growth, even though presenting lower fresh weight than NS-plants. STW-plants’ growth was limited essentially by nutrient deficiency, and PTW-plants were affected by nutrient deficiency, pH values, solid load, and N-NO2 concentration. Higher temperatures in summer led to faster crop growth, and lower temperatures in winter allowed better nutrient uptake by the crop. Wastewater-grown plants did not evidence toxicity in leaf extracts up to 1 % w/v. Coliform enumeration data indicated an accumulation in plant roots, with high removal from the wastewater. E. coli was not detected on plants’ leaves and total coliforms were within acceptable limits. Furthermore, the results point to an improvement in the wastewater quality, with minimum removal values of 75.2 % BOD5, 83.1 % COD, 43.4 % P, 44.9 % N, and 90.4 % K. The results demonstrated the viability of wastewater reuse for hydroponic production allowing a better understanding of its processes and contributing to mitigating water scarcity for food production, and the impacts of treated wastewater discharge in freshwater courses, particularly those associated with nutrient delivery to aquatic systems.

Development of a simple and low-cost method for the elimination of indicator bacteria from domestic wastewater discharges to the Huacapa River in Guerrero, Mexico

Development of a simple and low-cost method for the elimination of indicator bacteria from domestic wastewater discharges to the Huacapa River in Guerrero, Mexico