Search Results (61)

The aim of this study is to determine the characteristics of the chemical and mineral composition of sediment layers in a technogenic settling pond. This pond is located on urban land in Berezniki (Perm Krai, Russia), outside the territory of operating industrial facilities, and contains alkaline saline industrial wastes. The origin of this waste was related to sludge from the Solvay soda production process, which had been deposited in this pond over a long period of time. However, along with the soda waste, the pond also received wastewater from other industries. As a result, the accumulated sediment is characterized by variation in morphological properties both in depth and laterally. Five undisturbed columns were taken to study the composition of the accumulated sediment. The obtained samples were analyzed by X-ray diffraction (XRD), synchronous thermal analysis (STA), and X-ray fluorescence (XRF) analysis. The results showed that the mineral composition of bottom sediments in each layer of all studied columns is characterized by the predominance of calcite precipitated from wastewater. Along with calcite, due to the presence of magnesium and sodium in the solution, other carbonates precipitated—dolomite and soda (natron), as well as complex transitional carbonate phases (northupite and trona). Together with carbonate minerals, the chloride salts halite and sylvin, sulfate minerals gypsum and bassanite, and pyrite and nugget sulfur were established. The group of terrigenous mineral components is represented by quartz, feldspars, and aluminosilicates. The chemical composition of sediments in the upper part of the section generally corresponds to the mineral composition. In the lower sediment layers, the role of amorphous phase and non-mineral compounds increased, which was determined by the results of thermal analysis. The content of heavy metals and metalloids also increases in the middle and lower sediment layers. When categorized according to the Igeo value, an excessive degree of contamination (class 6) was observed in all investigated columns for copper content (Igeo 5.2–6.1). Chromium content corresponds to class 5 (Igeo 4.1–4.6), antimony to class 4 (Igeo 3.0–4.0), and lead, arsenic, and vanadium to classes 2 and 3 (moderately polluted and highly polluted). The data obtained on variations in the mineral and chemical composition of sediments represent the initial information for the selection of methods of accumulated waste management. Full article

Universities and other institutes of higher education could be considered as key actors in the implementation of sustainability pillars, such as the adoption of sustainable practices in wastewater management. However, the adoption of such practices is still an emerging issue. This paper discusses the design and operation of the first combined Oxylag and high rate algal pond (COHRAP) constructed at the university campus in Tunisia for irrigation. Performance was evaluated based on the removal efficiencies of nutrients, chemical oxygen demand (COD), biochemical oxygen demand (BOD), heavy metals, coliforms, and biomass productivity. The potential reuse of sludge and algal biomass is discussed based on the Tunisian national standard regulation for sludge reuse in agriculture (NT 106.20) and the European regulation (EC, 2019/1009) for fertilizer products. Effluent phytotoxicity is tested on the germination and growth on Zea mays L. The results indicate that the COHRAP performance was globally satisfactory; however, biomass productivity (1.4 g m⁻²d⁻¹) was low, indicating the need for adjustments in the operational parameters. Despite the effluent limitations for TSS and Hg, no phytotoxic effect was observed. Regarding the heavy metal content in sludge and algal biomass, the results obtained were in compliance with NT 106.20 and EC, 2019/1009), respectively. The energy consumption of COHRAP is 1.05 kWh/m³ resulting in operational costs of 0.29 euros/m³. This study revealed that COHRAP could be a sustainable option to treat wastewater from university campuses with resource recovery. Such a choice can be improved by the implementation of an algae recovery step. Full article

In the face of acute water scarcity and sanitation challenges emblematic of arid and semi-arid regions (ASARs), this study investigated the transformative upgrade of the Aqaba Conventional Activated Sludge Wastewater Treatment Plant (CAS-AWWTP) in Jordan. The project, expanding capacity to 40,000 m³/day, integrated sustainable features including renewable energy and repurposed natural treatment ponds functioning as artificial wetlands. The plant’s treatment performance, byproduct valorization, and alignment with sustainable development goals (SDGs) were assessed. Comparative analysis revealed that the upgraded CAS-AWWTP consistently outperforms the previous natural and extended activated sludge systems. CAS-AWWTP average removal efficiencies of BOD₅, COD, TSS, and T-N were 99.1%, 96.6%, 98.7%, and 95.1%, respectively, achieving stringent reuse standards and supplying approximately 30% of Aqaba Governorate’s annual water budget, thus conserving freshwater for domestic use. Furthermore, the plant achieved 44% electrical self-sufficiency through renewable energy integration, significantly reducing its carbon footprint. The creation of artificial wetlands transformed the site into a vital ecological habitat, attracting over 270 bird species and becoming a popular destination for birdwatching enthusiasts, drawing over 10,000 visitors annually. This transformation underscores the plant’s dual role in wastewater treatment and environmental conservation. The AWWTP upgrade exemplifies a holistic approach to sustainable development, impacting multiple SDGs. Beyond improving sanitation (SDG 6), it enhances water reuse for agriculture and industry (SDG 6.4, 9.4), promotes renewable energy (SDG 7), stimulates economic growth (SDG 8), strengthens urban sustainability (SDG 11), fosters resource efficiency (SDG 12), and supports biodiversity (SDG 14/15). The project’s success, facilitated by multi-stakeholder partnerships (SDG 17), provides a replicable model for water-scarce regions seeking sustainable wastewater management solutions. Full article

Integrated aquaculture–agriculture systems are recognized as sustainable solutions to optimize resources, support livelihoods, and enhance food security in climate-sensitive Sahelian regions. In contexts like Burkina Faso, runoff water harvesting ponds (RWHPs) improve agricultural yields during the rainy season but remain underutilized for the rest of the year. This study assesses the feasibility of integrating fish farming into these ponds. Using the Waso-2 tool, structured perception interviews were conducted with 51 farmers across 17 localities. Welch ANOVA and Games–Howell tests revealed, on a scale of 20, that water insufficiency scored 16.01 among experienced farmers without additional water access as a key obstacle, while pond degradation scored 17.69 for those with water access. For motivations, income generation scored 16.24 among inexperienced farmers, whereas training opportunities scored 17.65 for experienced ones, highlighting varying priorities across strata. Farmers preferred fish farming effluents over NPK for vegetables, scoring 15.99. Some favored raw effluents for immediate use, scoring 13.91, while others preferred decanted water with dried sludge for gradual nutrient release, scoring 12.39. This study demonstrates strong farmer interest in integrated RWHP systems. Enhancing pond retention, supplementing groundwater, and providing tailored training in aquaculture practices, pond maintenance, and water management are recommended to encourage adoption. Full article

Acid mine drainage (AMD) forms in mining areas during or after mining operations cease. This is a primary cause of environmental pollution and poses risks to human health and the environment. The hydrographic system from the Maramureș mining industry (especially the Baia Mare area) was heavily contaminated with heavy metals for many years due to mining activity, and after the closing of mining activity, it continues to be polluted due to water leaks from the abandoned galleries, the pipes, and the tailing ponds. The mineralization in the Băiuț area, predominantly represented by pyrite and marcasite associated with other sulfides, such as chalcopyrite, covelline, galena, and sphalerite, together with mine waters contribute to the formation of acid mine drainage. The Breiner-Băiuț mining gallery (copper mine) permanently discharges acidic water into the rivers. The efficiency of iron scrap (low-cost absorbent) for the treatment of mine water from this gallery was investigated. The treatment of mine water with iron shavings aimed to reduce the concentration of toxic metals and pH. Mine water from the Breiner-Baiut mine, Romania, is characterized by high acidity, pH = 2.75, and by the association of many heavy metals, whose concentration exceeds the limit values for the pollutant loading of wastewater discharged into natural receptors: Cu—71.1 mg/L; Zn—42.5 mg/L; and Fe—122.5 mg/L. Iron scrap with different weights (200 g, 400 g, and 600 g) was put in contact with 1.5 L of acid mine water. After 30 days, all three treatment variants showed a reduction in the concentrations of toxic metals. A reduction in Cu concentration was achieved below the permissible limit. In all three samples, the Cu concentrations were 0.005 for Sample 1, 0.001 for Sample 2, and <LOQ for Sample 3. The Zn concentration decreased significantly compared to the original mine water concentration from 42.5 mg/L to 1.221 mg/L, 1.091 mg/L, and 0.932 mg/L. These values are still above the permissible limit (0.5 mg/L). The Fe concentration increased compared to the original untreated water sample due to the dissolution of iron scrap. This research focuses on methods to reduce the toxic metal concentration in mine water, immobilizing (separating) certain toxic metals in sludge, and immobilizing various compounds on the surface of iron shavings in the form of insoluble crystals. Full article

The concentrations of estrogens and xenoestrogens in the environment are rising rapidly, posing significant and multifaceted risks to human health and ecosystems. It is imperative for governments to develop policies that leverage sustainable technologies to mitigate the presence of pharmaceutical estrogenic compounds in the environment. This review examines the global environmental and human health risks associated with indigenous estrogens and synthetic pharmaceutical xenoestrogens, while critically evaluating sustainable approaches to their management. A total of 28 studies, published between December 2013 and 18 January 2024, and sourced from PubMed and Scopus, were systematically reviewed. Most of these studies focused on estrogenic compounds in aquatic environments where they contribute to reproductive and developmental abnormalities in fish and may enter the human food chain, primarily through fish consumption. Sustainable methods for removing or neutralizing estrogenic compounds include adsorption, filtration, and enzymatic degradation. Additionally, technologies such as activated sludge processes and high-rate algal ponds demonstrate promise for large-scale applications; however, further research and standardized operational guidelines are needed to optimize their efficiency and sustainability. This review has concluded that ECs can have severe consequences on the environment, most notably, impairment of reproductive functions in fish and humans, underscoring the urgent need for governments to implement drug take-back programs, establish evidence-based guidelines for wastewater and pharmaceutical waste treatment, and set enforceable thresholds for estrogenic compounds in surface and drinking water. Existing regulations such as the UK’s Regulation on the registration, evaluation, authorization, and restriction of chemicals and the United States’ National Primary Drinking Water Regulations can be modified to include ECs as dangerous chemicals to aid in maintaining safe EC levels”. Such measures are critical for reducing the environmental concentrations of pharmaceutical estrogenic compounds and safeguarding both public health and ecological integrity. Full article

Plastics are vital for society, but their usage has grown exponentially and contributes to the growth of pollution worldwide. The World Health Organization, WHO, already reported that microplastics (MPs) are found everywhere, in waste and fresh water, and in the air and soil. Regarding water effluents, waste-water treatment plants only minimize the problem, trapping only larger size particles. In contrast, smaller ones remain in oxidation ponds or sewage sludges, or are even released to aquifers environment. Classic procedures for MPs detection are still quite laborious, and are usually conducted off-line, involving several steps and expensive equipment. Electrical Impedance Spectroscopy, EIS, is a technique that allows the analysis of a system’s electrical response, yielding helpful information about its domain-dependent on physical-chemical properties. Due to the superficial electronegativity of MPs’ particles, EIS may allow to attain the purpose of the present work: to provide a fast and reliable method to detect/estimate MPs’ concentration in water effluents. Among the most common microplastics are Polyethylene, PE, and Polyvinyl Chloride, PVC. Using the developed setup and experimental data collection methodology, the authors could differentiate between MPs’ suspensions containing the same concentration of the different evaluated MPs, PVC and PE, and assess PVC concentration variation, in the interval between 0.03 to 0.5 g (w/w), with an error, estimated based on the obtained impedance modulus, around or below 3% for the entire stimulus signal frequency range (from 100 Hz to 40 MHz) for the PVC particles. Full article

The management of domestic wastewater in rural areas has always been challenging due to characteristics such as the wide distribution and dispersion of rural households. There are numerous domestic sewage discharge methods used in rural areas, and it is difficult to treat the sewage. To address this problem, decentralized wastewater treatment systems (DWTSs) have been installed around the globe to reuse and recycle wastewater for non-potable uses such as firefighting, toilet flushing, and landscape irrigation. This study compares the currently implemented treatment processes by investigating them from the point of view of their performance and their advantages and disadvantages to provide new ideas for the development of rural wastewater treatment technologies. According to conventional treatment technologies including activated sludge (OD, A/O, A/A/O, SBR), biofilm (biofilter, MBBR, biological contact oxidation, biofluidized bed) and biogas digesters, natural biological treatment technologies including artificial wetlands (surface flow, vertical flow, horizontal submerged flow artificial wetlands), soil percolation systems (slow, fast, subsurface percolation and surface diffusion) and stabilization pond technology and combined treatment technologies are categorized and further described. Full article

Disposal of biosolids, the solid fraction of sewage treatment, is a global environmental issue. Biosolids contain valuable organic matter and plant nutrients; however, they also contain contaminants including trace elements, xenobiotics, and pathogens. The quality of the biosolids greatly depends on the source of wastewater (i.e., industrial vs. domestic) and the treatment processes. We aimed to determine the potential of three distinct biosolids and one pond sludge to grow indigenous plants for ecosystem restoration. For each amendment, we tested six indigenous species, Veronica salicifolia, Corokia cheesemanii, Griselinia littoralis, Phormium tenax, Poa cita, and Cordyline australis in bark mixed with biosolids and/or pond sludge at rates of 0–50%. There was a significant positive correlation between plant growth and biosolid addition up to a species-dependent plateau. Growth decreased at the highest rates. At a rate of 10% for fresh biosolids and 30% for aged biosolids provided consistent optimal growth across all species. The pond sludge was unsuitable for the establishment of indigenous seedlings. At the optimal rates, there were significant increases in foliar N, P, K, S, and Zn. None of the trace elements accumulated in the plants at phytotoxic concentrations or levels that presented a risk to ecosystems. Future work should determine how plants raised with biosolids perform once planted out in the field. Full article

In recent years, the mining industry of slate stone in Spain, from Castille and Leon, has grown significantly due to construction and building sector demands. The continuous accumulation of cutting sludges in ponds from mining and processing operations brings associated environmental problems if the cutting sludges are not properly treated. A potential environmental mitigation measure is the valorization of cutting sludges for the development of new binder materials through geopolymerization. Therefore, this research focused its attention on studying the feasibility of slate stone cutting sludges as a source of aluminosilicates for geopolymer conformation. For this experiment, the mining raw material was analyzed through a typical characterization test campaign in order to validate its feasibility as a source of aluminosilicates for geopolymerization. Subsequently, geopolymers were prepared with slate stone cutting sludges and a 12 M concentration using different Na₂SiO₃/NaOH ratios (5, 2.5, 1.6, 1.25, and 1). Geopolymer samples were tested, and their physical and mechanical characteristics were evaluated. The test results show that an alkali activator with a 2.5 ratio led to better mechanical and physical properties, with a 7-day compressive strength value of 27.23 MPa. Therefore, this research aims to demonstrate that slate stone cutting sludge could constitute a sustainable binder material for construction purposes. Full article

Soil salinization negatively affects rice growth and yield; however, how different sludge sources regulate rice growth and yield under salt stress was rarely investigated. This study evaluated the performance of two salt-tolerant rice cultivars, Chaoyou 1000 and Longliangyou 506, grown in two sediment sources, pond sediment (PS) and river sludge (RS), under salt stress (56 ds m⁻¹ brine irrigation) with conventional soil (CS) used as the control. The results showed that the rice yield under the PS and RS treatments was enhanced by 51.0% and 43.6% as compared with CS, respectively, owing to an improvement in spikelet per panicle, 1000-grain weight, dry matter accumulation, and the chlorophyll content in both rice cultivars. Compared with CS, the total nitrogen accumulation, nitrogen grain production efficiency, nitrogen harvest index, and nitrogen partial productivity under the PS and RS treatments were increased by 18.9–28.9%, 17.0–20.6%, 7.2–16.6%, and 43.8–50.9%, respectively. Moreover, rice grown in PS and RS showed higher activities of nitrogen metabolism-related enzymes (nitrate reductase, glutamine synthetase, and glutamate synthetase) at the heading stage and higher K⁺ and K⁺/Na⁺ contents in the leaves. Overall, a balanced utilization of sediment resources (especially pond sediment) can effectively alleviate salt stress and improve the yield and nitrogen use efficiency in rice. Full article

The use of bacterial and microalgal consortia to remove nitrogen from wastewater has garnered attention as a potential alternative to conventional systems. This approach not only reduces energy consumption but also aids in nutrient recovery. Light is essential for algae photosynthesis; however, nitrifying bacteria are also influenced by light radiation. This mini-review summarizes the current knowledge concerning photoinhibition, the light stimulation of ammonia-oxidizing bacteria (AOB), resistance to light radiation, the implementation of microalgal–bacterial systems, and the possible mechanisms involved. Nitrosomonadaceae AOB and Nitrospiraceae nitrite-oxidizing bacteria (NOB) often coexist in a microalgal–bacterial system. Studies have suggested that AOB can tolerate light radiation at 200 μmol m⁻²·s⁻¹ in microalgal–bacterial systems, whereas NOB are almost completely suppressed, which can result in partial nitrification in the bioreactor. An appropriate light level can stimulate AOB growth in microalgal–bacterial granular reactors and may improve algae metabolic activity. Granular sludges or artificial “light-shielding hydrogel” could effectively protect nitrifying bacteria from light intensities up to 1600 μmol m⁻²·s⁻¹ in wastewater treatment reactors. Microalgal–bacterial systems along with the associated “algal shading effect” have been widely used in pond aquaculture. This approach minimizes the need for costly mechanical aeration through photo-oxygenation and facilitates nutrient recovery by filter-feeding fish. Full article

This research examines whether ultrasonic waves can enhance the hydrolysis, stability, and dewatering of activated sludge from raw urban wastewater. Sampling and physical examination of the activated sludge that was returned to the aeration pond were carried out using ultrasonic waves that were guided at frequencies of 30 and 50 kHz for periods of 0.5, 1, 3, 5, 10, 15, and 30 min. Various tests, including volatile suspended solids, inorganic solids, volatile solids, sludge resistant time, capillary suction time, total suspended solids, total solids, and volatile soluble solids, were carried out to advance further the processes of hydrolysis, stabilization, and dehydration of samples. According to the observations, the volatile soluble solids at a frequency of 30 kHz and $t=15$ min were raised by 72%. The capillary suction time of 30 and 50 kHz in 1 min demonstrated a drop of 29 and 22%, respectively. It is crucial to consider that, at 10 min and the frequency of 50 kHz, the greatest efficiency was found. The 30 kHz and 1 min yielded the optimum sludge dewatering conditions. Finally, artificial neural networks (ANN) are utilized to propose predictive models for concentration, and the results were also very accurate ($\mathrm{M}\mathrm{A}\mathrm{E}=1.37\%$). Regarding the computational costs, the ANN took approximately 5% of the time spent on experiments. Full article

Bali Province, Indonesia, experiences serious water shortages and groundwater over-abstraction due to rapidly increasing water demand. Therefore, this study aimed to assess the potential for water reclamation and reuse in Bali Province, focusing on the operational performance of two wastewater treatment plants (WWTPs). Although the Suwung WWTP could increase its treatment capacity to produce reclaimed water for irrigation and landscape, there are multiple management issues to be addressed, including fluctuating water demand, limited customer base beyond hotels, concerns about water quality and safety, and cultural perceptions of reclaimed water. In addition, despite the organic loading rates being lower than the design value, the treatment performance of the Suwung WWTP was found to be significantly lower than that of the ITDC WWTP, which achieved high BOD, COD, and TSS removal rates by performing good maintenance of aerators and post-treatment based on dissolved air flotation (DAF). Causal loop analysis indicates that aerator malfunctioning causes multiple problems, such as low dissolved oxygen, poor BOD removal, sludge carryover, and low sludge concentrations. Therefore, regular maintenance of aerators, as well as the development of aerators robust against malfunctioning, are fundamental to producing effluents from stabilization ponds that meet the requirements for irrigation and landscape reuse. Full article

In this study, the iron-based carbon composite (hereafter FCN-x, x = 0, 400, 500, and 600 calcination) was synthesized by a simple high-temperature pyrolysis method using iron-containing sludge coagulant generated from wastewater treatment settling ponds in chemical plants. The FCN-x was used for the adsorptive reduction of aqueous phase Cr(VI) effectively. The FCN-x was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier infrared spectrometer (FT-IR), X-ray photoelectron spectrometer (XPS), and Brunauer-Emmett-Teller theory (BET). FCN-x adsorption of Cr(VI) was examined in batch experiments using CrO₄²⁻ as a function of physicochemical parameters. The chemical kinetics of Cr(VI) adsorption by FCN-500 were modeled by 1st and 2nd order empirical pseudo kinetics. Based on these experiments, FCN-500 has been selected for further studies on Cr(VI) adsorptive reduction. The maximum Cr(VI) adsorption by FCN-500 was 52.63 mg/g showing the highest removal efficiency. The Cr(VI) adsorption by the FCN-500 was quantified by the Langmuir isotherm. XPS result confirmed the reduction of Cr(VI) to Cr(III) by the FCN-500. The iron-based carbon composites have high reusability and application potential in water treatment. The electroplating wastewater with 117 mg/L Cr(VI) was treated with FCN-500, and 99.93% Cr(VI) was removed within 120 min, which is lower than the national chromium emission standard of the People’s Republic of China. This work illustrates the value-added role of sludge generated from dye chemical plants to ensure environmental sustainability. Full article