Search Results (26)

The design of a water treatment plant requires thorough analysis of water quality, capacity, location, and reliable technologies. Groundwater sources with elevated levels of organic matter, color, arsenic, and dissolved gases represent a particular challenge for treatment. In this study, the application of dissolved air flotation (DAF) was systematically investigated as a pretreatment method for groundwater purification. Jar test experiments were conducted to evaluate the removal of total organic carbon (TOC), color, and arsenic under various coagulant dosages. The results demonstrated that DAF achieved up to 65% TOC removal and significant arsenic reduction, while also improving water color. Compared with conventional pretreatment, optimized DAF conditions provided higher efficiency and practical applicability for real-world water treatment plant design. The findings highlight the potential of DAF as an effective technology for addressing complex groundwater contamination and contribute to expanding its use beyond conventional surface water treatment. Full article

The flocculation-based purification of quarry wastewater continues to pose a significant challenge in mineral processing and environmental engineering, primarily due to persistent turbidity issues and inefficient floc settling behaviour. In this study, we systematically investigate the synergistic effects of organic and inorganic flocculants to reduce turbidity and improve floc settling performance. Through a series of optimised experiments using polyaluminium chloride as an inorganic flocculant, polyacrylamide as an organic flocculant, and calcium oxide as a pH regulator agent, the treatment efficiency was evaluated. Under the optimal conditions with 200 g/m³ CaO as the regulator agent and 2.5 g/m³ PAC and 12 g/m³ PAM as flocculants, the residual turbidity was reduced to 97.30 NTU, meeting stringent industrial discharge standards and enabling zero-discharge water reuse. Zeta potential measurements, optical microscopy, and DLVO theory collectively elucidated the interfacial interactions between flocculants and mineral particles, with zeta potential revealing electrostatic effects, microscopy visualising aggregation patterns, and DLVO theory modelling revealing colloidal stability, thereby mechanistically explaining the enhanced aggregation behaviour. Full article

Brewery wastewater (BWW) often contains a high concentration of organic matter and nutrients, requiring pre-treatment before it can be effectively treated in conventional wastewater treatment plants. This study focuses on the use of coagulation–flocculation techniques to treat real industrial wastewater. Firstly, lab-scale tests have been carried out to determine the most effective coagulant and flocculant type and concentration. The levels of pollutants, including chemical oxygen demand (COD), biological oxygen demand in five days (BOD₅), total nitrogen (N_tot), total phosphorus (P_tot), and orthophosphate (P-PO₄³⁻) have been measured to assess the efficiency of the procedure. Industrial scale tests were performed in optimal conditions in order to evaluate the effectiveness of the treatment on a larger scale and estimate the generation of chemical sludge. The most effective substances for coagulation and flocculation were polyaluminium chloride (PAC) and anion-active flocculant (AAF) ZETAG 4139 0.1%, respectively, at concentrations of 675 mg·L⁻¹ and 40 mg·L⁻¹. During industrial-scale tests, the process allowed the effective removal of TSS (86.8%), N_tot (51.8%), P_tot (95.5%), and P-PO₄³⁻ (99.6%), while the limited removal of organic substances has been highlighted (BOD₅: 34.3%; COD: 26.5%). The dry matter (DM) content of the separated sludge was found to be 4.5–5%, and a yield of 1.01 kg_DM per kg of COD removed was obtained after flocculation treatment of the BWW. These findings can be beneficial for both the scientific community and technical operators, offering insights into the effectiveness of various coagulants and flocculants on industrial-scale wastewater treatment. Full article

As the quantity and quality of water resources decreases, the need for timely and valid prediction of the WTP of drinking water-used chemicals to produce quality drinking water for the final consumer increases. The question that arises is which prediction model performs better in predicting the chemical dosages used in a WTP of drinking water. ANNs or the MLR analysis models? The present study is a comparative study between the two aforementioned prediction models. The evaluation criteria chosen are: the Root Mean Square Error (RMSE), the Coefficient of Determination (R²), and the Pearson Correlation Coefficient (R). A previously optimised ensemble ANN model was chosen, which consisted of 100 neural networks, with 42 hidden nodes each, 10 inputs, and 4 outputs. On the other hand, four different scenarios in MLR analysis with dependent variables were examined: the ozone (O₃) concentration, the Anionic Polyelectrolyte (ANPE) dosage, the Poly-Aluminium Chloride hydroxide sulphate (PACl) dosage, and the chlorine (Cl_2(g)) dosage. As independent variables, 10 WTP operational and quality water variables were considered. According to RMSE results, the MLR model had better performance for the three (RMSE ANPE = 0.05 mg/L, RMSE PACl = 0.08 mg/L, and RMSE Cl_2(g) = 0.10 kg/h) of the four used WTP of drinking water chemicals, than the ANN model, which performed better for only one (RMSE O₃ = 0.02 mg/L). According to R² and R results, the ANN model had better performance compared to the MLR analysis model for all four variables. Based on the criterion of R² > 0.5, the ANN performance was satisfactory in predicting three variables: ANPE (R² = 0.772), PACl (R² = 0.742), and Cl_2(g) dosage (R² = 0.838, +23% and R = 0.91553, +11%). Respectively, the prediction of the MLR analysis model was evaluated as satisfactory only for the Cl_2(g) dosage (R² = 0.681, R = 0.82500). If someone wants to use the above described (ANN or MLR) scenarios to predict Cl_2(g) dosages, it is better to use the one with the smallest RMSE. If they are interested in fitting purposes, the one with the largest R², is preferable. Also, the ozone concentration variable showed low values of the R², in all cases, possibly due to the large variation in its values. This study further strengthens the opinion that ANNs are useful decision support tools for a WTP of a drinking water operator and can accurately and sufficiently mimic the decisions regarding the used chemical dosages, which is the main daily concern of the plant operator. Full article

This is the first study to describe a novel, patented process for the on-site synthesis and subsequent direct utilisation of Polyferric Chloride (PFC) at low Fe concentration dosing, which aims to facilitate the potential replacement of Polyaluminium Chloride (PAC) during surface water treatment (e.g., from reservoirs) for drinking water production. For this purpose, the PFC was synthesised and subsequently used as a coagulant in simulated surface water samples under different synthesis and coagulation/flocculation conditions, namely for different pre-hydrolysed Fe concentrations, pre-hydrolysis pH, coagulation pH, and flocculation times. The effectiveness of PFC was examined mainly in terms of total organic carbon (TOC) removal and the residual Fe concentration. The obtained results showed that the pre-hydrolysed Fe concentration at 0.5 ± 0.25%, pre-hydrolysis at pH 2.5 ± 0.25, coagulation at pH 5.5–7.0 and a flocculation time of 5 min could result in the highest TOC removal (i.e., residual values < 0.60 mg/L) and the lowest residual Fe concentration (<5 μg Fe/L), which is acceptable for a water quality assessment. These values are also substantially lower when compared to the respective TOC and residual metal concentrations using PAC (usually, the relevant obtained values are around TOC > 1 mg/L and Al > 50 μg/L). Full article

The process of accelerated eutrophication forces the search for innovative, effective methods to restore the quality of surface waters. This study was conducted on shallow, urban Lake Mielenko (Maximum depth 1.9 m; Mean depth 1.3 m) in the context of implementing a new, sustainable method of lake restoration, i.e., phosphorus inactivation by sequential application of two types of coagulants. Approximately 9.9 tons of polyaluminium chloride (trade name PAX 18) were introduced into the profundal zone of Lake Mielenko, and 9.0 tons of iron chloride (trade name PIX 111) in the coastal area. The applications were divided into two spring and two autumn stages. Before restoration, the mean P_min. concentration in Lake Mielenko water was 0.031 mg P/L, and TP was in the range of 0.091 to 0.346 mg P/L. After restoration, the average content of P_min. was 0.007 mg P/L (a decrease of 80%), and the average value of TP was 0.096 mg P/L (a decrease of 72%). The obtained results indicate that phosphorus inactivation does not change nitrogen compounds’ content. However, due to the application of coagulants, P content decreased, i.e., the main factor limiting photosynthesis, which resulted in a significant decrease in primary production in Lake Mielenko. Before restoration, the average content of N-NH₄ was 0.100 mg N/L, N-NO₃—0.145 mg N/L, N_org. 1.70 mg N/L, and TN—1.86 mg N/L. After restoration, the average content of N-NH₄ was 0.096 mg N/L, N-NO₃—0.123 mg N/L, N_org. 1.28 mg N/L, and TN—1.50 mg N/L. This also resulted in a reduction in the N_org. content, as well as a reduction in the amount of chlorophyll a (from 30.51 to 13.41 mg/m³), organic compounds (BOD₅ from 8.9 to 4.6 mg O₂/L), and an increase in water transparency to the bottom (up to 1.45 m on average). The results obtained in Lake Mielenko indicate that the innovative method of phosphorus inactivation, which involves the sequential application of two types of phosphorus-binding preparations, is an excellent solution that ensures higher ecological safety in the coastal areas of the reservoir and also allows for a significant reduction in restoration costs. Full article

Synthetic fibers enter wastewater treatment plants together with natural fibers, which may affect treatment efficiency, a fact not considered in previous studies. Therefore, the aim of the present study was to evaluate the efficiency of the coagulation/flocculation process for the removal of a mixture of textile fibers from different water matrices. Natural and synthetic fibers (100 mg/L; cotton, polyacrylonitrile, and polyamide) were added to a synthetic matrix, surface water and laundry wastewater and subjected to coagulation/flocculation experiments with ferric chloride (FeCl₃) and polyaluminum chloride (PACl) under laboratory conditions. In the synthetic matrix, both coagulants were found to be effective, with FeCl₃ having a lesser advantage, removing textile fibers almost completely from the water (up to 99% at a concentration of 3.94 mM). In surface water, all dosages had approximately similar high values, with the coagulant resulting in complete removal. In laundry effluent, the presence of surfactants is thought to affect coagulation efficiency. PACl was found to be effective in removing textile fibers from laundry wastewater, with the lowest removal efficiency being 89% and all dosages having similar removal efficiencies. Natural organic matter and bicarbonates showed a positive effect on the efficiency of FeCl₃ in removing textile fibers from surface water. PACl showed better performance in coagulating laundry wastewater while surfactants had a negative effect on FeCl₃ coagulation efficiency. Full article

Many coagulants such as aluminium sulfate, ferric sulfate, and ferrous sulfate have been investigated in the past, but there is a lack of data on their effectiveness to some specific water quality parameters. This study aimed at investigating the efficiency of the coagulation water treatment process to remove pollutants such as total organic carbon (TOC), total nitrogen (TN), and total suspended solids (TSS) from urban drinking water. The polyaluminium chloride (PAC) coagulant was applied to determine the impact of the treatment process on the structure and diversity of these pollutants in urban drinking water. All water samples were collected from the Yangtze River, Baoshan district, Shanghai, China, over a period of three months which coincided with the late summer and early winter periods. Specific to different coagulant characterizations, a preliminary test was performed with three other coagulants, namely, aluminium sulfate, polyaluminium, silicate sulfate, and ferric sulfate to determine their optimal conditions for floc characterization and removal efficiencies. In summary, the overall performance of the PAC coagulant was better than that of the other three coagulants used in the pre-treatment of the sampled water. The obtained results revealed that under the optimum operating conditions, the doses of the PAC were as follows: 20, 35, 50, 65, and 80 mgL⁻¹, respectively. The water temperature and pH were determined by using a pH meter, the TOC and TN determined by using a TOC analyzer, and the TSS by following the ASTM D2540 method. Furthermore, the response surface methodology by the Box–Behnken optimization analysis was applied to coagulant dosage, temperature, pH, and three corresponding dependent factors (TSS, TOC, and TN) to determine the best optimal conditions for the PAC performance. To determine whether or not the quadratic model adequately explained and predicted the response during the coagulation process, an analysis of variance was performed. Multiple optimal factors were identified for the urban drinking water treatment, including a pH value of 6.9, water temperature of 20.1 °C, and a coagulant dosage of 9.7 mgL⁻¹. Full article

The aim of this study was to evaluate the effectiveness of the coagulation process using highly polymerised polyaluminium chlorides in reducing the level of pollution of water in a mixture of groundwater and surface water. The coagulants used were prehydrolysed polyaluminium chlorides with the trade names PAXHP908 and PAXXL1911 that had alkalinity 85% and different iron contents (<0.01% and 0.7%). The Al species distribution in the PACls (PAXXL1911 ad PAXHP908) samples were analysed by the Ferron complexation timed spectrophotometry. The content of polymer forms of aluminium (Al_b) in the tested coagulants was 40%. The worse results in the removal of organic matter (TOC, DOC, UV₂₅₄), iron, colour and turbidity in the coagulation process were produced by the PAXXL1911, possessing higher content of iron (0.7%). The lower usefulness of the PAXXL1911 was probably caused by the interaction of organic ligands present in the treated water and Fe(III) ions introduced into the water with the coagulant. The effectiveness of the coagulation process with the tested coagulants was also evaluated by measuring the electrokinetic potential ζ, which determines the stability of the colloidal system. Full article

For solving the problem of low efficiency about dyes and slow precipitation rate for powdered activated carbon (PAC), this study successfully prepares a kind of powdered activated carbon-based composites (PACMC) to remove Rhodamine B (RhB) in wastewater as an adsorbent. PACMC derived from potassium humate and polyaluminium chloride (PACl)-modified PAC were fabricated via a chemical precipitation method. We confirmed the micro-morphology and chemical composition of PACMC by scanning electron microscopy energy-dispersive X-ray spectrometer (SEM-EDS) and fourier infrared spectroscopy (FT-IR), certifying that PACMC was synthesized by chemical reaction of raw materials. PACMC has layered porous structure and functional groups, which is beneficial to the transport and diffusion of RhB molecules. The specific surface area (10.098 m²·g⁻¹) and average particle size (142.9 µm) of PACMC and the specific surface area (710.1 m²·g⁻¹) and average particle size (11.9 µm) of PAC were measured. By comparison, it can be seen that PACMC has larger average particle size conducive to solid–liquid separation. The static adsorption experiments were carried out to investigate the adsorption properties of RhB by PACMC. The results showed that the adsorption capacity of PACMC for RhB was 2–3 times as high as that of PAC. The pH value of the solution had a significant effect on the adsorption of RhB by PACMC and the maximum adsorption was observed at pH = 4.5 (q_e = 28.56 mg·g⁻¹, C₀ = 40 mg·L⁻¹). The adsorption of RhB by PACMC can be well described by the pseudo-second-order kinetics. The kinetic results revealed that the adsorption process involved several steps, where the chemical adsorption and intra-particle diffusion both played the important roles. The isothermal adsorption data were in accordance with the Dubinin–Radushkevich model, which indicated that the adsorption was dominated by the chemisorption mechanism. Therefore, the adsorption mechanisms included chemical binding/chelation effect and electrostatic adsorption effect. Full article

In this paper, to enhance the toughness and heat resistance properties of polylactic acid (PLA)/polybutylene succinate (PBS) composites, the PLA/PBS matrix was modified by different glass fiber (GF), GF/SiO₂, and GF/(Polyaluminium chloride) PAC fillers. Additionally, the effect of filler type, filler content, components interaction and composite structure on the mechanical and thermal properties of the PLA/PBS composites was researched. The results showed that the addition of GF, GF/SiO₂ and GF/PAC make the PLA/PBS composites appear significantly higher mechanical properties compared with the pristine PLA/PBS composite. Among the different inorganic fillers, the 10%GF/1%SiO₂ fillers showed excellent strengthening, toughening and heat resistant effects. Compared with the pristine PLA/PBS matrix, the tensile strength, elastic modulus, flexural strength, flexural modulus and Izod impact strength improved by 36.28%, 70.74%, 67.95%, 66.61% and 135.68%, respectively. Considering the above, when the weight loss rate was 50%, the thermal decomposition temperature of the 10%GF/1%SiO₂ modified PLA/PBS composites was the highest 412.83 °C and its Vicat softening point was up to 116.8 °C. In a word, the 10%GF/1%SiO₂ reinforced PLA/PBS composites exhibit excellent mechanical and thermal properties, which broadens the application of biodegradable materials in specific scenarios. Full article

With the annual increase in the sludge production in China’s sewage treatment plants, the problem of sewage sludge treatment and disposal is becoming more and more serious. Anaerobic fermentation can convert complex organic matter in sewage sludge into short-chain fatty acid, hydrogen, methane and other resources and is an effective method for sewage sludge treatment and disposal. At the same time, sewage sludge often contains flocculants, which will inevitably affect the effect of anaerobic fermentation. As a high-performance flocculant, polyaluminum chloride (PAC) is widely used in wastewater treatment and sewage sludge dewatering processes. Previous studies indicated that lower levels of PAC inhibit the effect of the anaerobic fermentation process of sewage sludge; on the other hand, it is necessary to understand the effects of higher levels of PAC in anaerobically fermented sewage sludge. The results showed that higher levels (0.2–1 g Al/g total solids (TS)) of PAC could promote acid production from anaerobically fermented sewage sludge. Moreover, mechanism studies suggest that higher levels (0.2–1 g Al/g total solids (TS)) of PAC caused excessive adsorption of the charge on the surface of the sewage sludge colloid and reversed the charge. The sewage sludge colloid was stabilized again, which increases the concentration of soluble proteins, polysaccharides, and soluble extracellular polymers (S-EPS) in the fermentation broth, thereby improving the anaerobically fermented sewage sludge efficiency. The results provided from this study may act as technical reference and guidance for the engineering application of sewage sludge anaerobic fermentation. Full article

The paper presents the results of the research on the restoration of the shallow Lake Domowe Duże in Szczytno (area 0.6 km², average depth 3.4 m). Restoration treatments were carried out in the years 2010–2012 and consisted in the inactivation of phosphorus using polyaluminium chloride. Technical restoration was supported by biomanipulation treatments consisting in stocking the lake with predatory fish. Water quality study were carried out before remediation and annually for a decade (2010–2019) during and after the application of coagulant. It was shown that the efficiency of removing excess phosphorus from water column was high (decrease from 0.23 mgP L⁻¹ to 0.05 mgP L⁻¹). The effects achieved during the coagulant application were maintained for 5 years after the end of the project. Currently, the phosphorus pool is still twice as low as before the treatments, but it is gradually increasing. The main external factor limiting permanent improvement of water quality is the open hydrological system and transport of biogenic matter by surface inflows draining anthropogenically transformed areas. Maintaining permanent improvement of water quality will require continuation of restoration measures. Full article

The application of lanthanum modified bentonite (Phoslock^®) and polyaluminium chloride (PAC) is popular in the restoration of European temperate lakes; however, the effects of the application on the concentrations of phosphorus (P) in both the water and the sediments have been poorly evaluated to date. We studied the effects of the application of Phoslock^® + PAC on the concentrations of total phosphorus (TP), particulate phosphorus (PP), soluble reactive phosphorus (SRP), total suspended solids (TSS) and chlorophyll a (Chla) in the water, and different P forms in the sediments, in an isolated part of Lake Yanglan. The results showed that the concentrations of TP, PP, SRP, TSS and Chla decreased significantly after the addition of Phoslock^® + PAC. Moreover, the concentrations of labile-P, reductant-soluble-P and organic-P in the sediments were also significantly decreased after the Phoslock^® + PAC application. However, the concentrations of both the stable apatite-P and residual-P in the sediments after application of Phoslock^® + PAC were much higher than the pre-addition values, while the concentrations of metal-oxide-P did not differ significantly between the pre- and post- application conditions. Our findings imply that the combined application of Phoslock^® and PAC can be used in the restoration of subtropical shallow lakes, to reduce the concentrations of P in the water and suppress the release of P from the sediments. Full article

Polyaluminium chloride (PAC) has been widely used as a chemical coagulant in water treatment. However, little is known about the impact of PAC performance on the microbial community in sediments. In this study, the archaeal, bacterial, and fungal communities in urban river sediments with and without PAC treatment were investigated. Prokaryotic diversity decreased at the PAC addition site (A2) and increased along with the river flow (from A3 to A4), while eukaryotic diversity was the opposite. The abundance of core microbiota showed a similar trend. For example, the dominant Proteobacteria presented the highest relative abundance in A1 (26.8%) and the lowest in A2 (15.3%), followed by A3 (17.5%) and A4 (23.0%). In contrast, Rozellomycota was more dominant in A2 (56.6%) and A3 (58.1%) than in A1 (6.2%) and A4 (16.3%). Salinity, total dissolved solids, and metal contents were identified as the key physicochemical factors affecting the assembly of core microorganisms. The predicted functions of archaea and fungi were mainly divided into methane cycling and saprotrophic nutrition, respectively, while bacterial function was more diversified. The above findings are helpful to enhance our understanding of microorganism response to PAC and have significance for water treatment within the framework of microecology. Full article