Search Results (7)

The paper presents new reactive materials, namely marl and travertine, and their thermal modifications and the Polonite^® material, analyzing their phosphorus removal from water and wastewater by sorption. Based on the experimental data, an analysis of the factors influencing the sorption capacity of the materials, such as the material dose, pH of the initial solution, process temperature, surface structure, and morphology, was performed. Adsorption isotherms and maximum sorption capacities were determined with the use of the Langmuir, Freundlich, Langmuir–Freundlich, Tóth, Radke–Praunitz, and Marczewski–Jaroniec models. The kinetics of the phosphorus sorption process of the tested materials were described using reversible and irreversible pseudo-first order, pseudo-second order, and mixed models. The natural materials were the most sensitive to changes in the process conditions, such as temperature and pH. The thermal treatment process stabilizes the marl and travertine towards materials with a more homogeneous surface in terms of energy and structure. The fitted models of the adsorption isotherms and kinetic models allowed for an indication of a possible phosphorus-binding mechanism, as well as the maximum amount of this element that can be retained on the materials’ surface under given conditions—raw marl (43.89 mg P/g), raw travertine (140.48 mg P/g), heated marl (80.44 mg P/g), heated travertine (282.34 mg P/g), and Polonite^® (54.33 mg P/g). Full article

A toolbox of methods must be available for the remediation of lakes and water bodies suffering from eutrophication. One method suggested is hypolimnetic withdrawal based on a closed-circuit system. Prior to the start of a pilot-scale test at Lake Hönsan, Sweden, a laboratory trial with containers filled with water and bottom sediment from this lake was performed. A peristaltic pump distributed equal bottom water volume to four columns, two filled with glass beads and two with the filter material Polonite, and then back to the surface of the containers. The reactive filter medium (RFM) removed phosphate (PO₄-P) efficiently (98.6%), despite the relatively low influent concentration (390 µg L⁻¹). The control column filled with glass beads, removed 2.9% of the PO₄-P. The anoxic sediment, containing 2.47 mg P g⁻¹, released PO₄-P, which was indicated by the increased concentration in near-bottom water. The redirected water after RFM filtration had high pH ($\overline{x}=11.1)$; however, an equalization took place in the water mass to a lower but still increased pH value $\left(\overline{x}=8.7\right)$ compared to the control $\left(\overline{x}=7.02\right)$. This article reports the pros and cons of a full-scale system using the proposed method. Full article

The predominant techniques used for road runoff treatment are sedimentation and filtration. In filtration systems, the ability of the media to adsorb the contaminants is a finite process. Consequently, construction, operation and maintenance managers of such systems should know in advance the service life, i.e., when the used medium should be replaced, and associated costs of operation and maintenance. A batch experiment followed by a packed bed reactor (PBR) experiment addressed the kinetics of the studied media argon oxygen decarburization slag (AOD) and Polonite, followed by the development of a 1D-model to describe the change of concentration of Cu and Zn within time. The batch test results showed that Cu and Zn adsorption followed the Freundlich isotherms for AOD and Polonite. Those results coupled with the linear driving force model and the developed model resulted in good agreement between the PBR results and the simulation. The model was capable to predict (i), the service life at the hydraulic load of 0.18 m/h for AOD (Cu: 395 d; Zn: 479 d) and Polonite (Cu: 445 d; Zn: 910 d), to show (ii) the profile concentration in the PBR within time and the gradient of the concentration along the height of the reactor. Full article

Many on-site wastewater treatment systems, such as soil treatment systems, are not sustainable in terms of purification efficiency, nutrient recycling potential, and economics. In this case study, a sequencing batch constructed wetland (SBCW) was designed and added after a package treatment plant (PTP) using reactive filter media for phosphorus (P) removal and recycling. The treatment performance of the entire system in the start-up phase and its possible applicability in rural areas were investigated. Raw and treated effluents were sampled during a period of 25 weeks and analyzed for nitrogen, phosphorus, BOD₇, and bacteria. Field measurements were made of wastewater flow, electrical conductivity, oxygen, and temperature. The entire system removed total-P and total inorganic nitrogen (TIN) by 83% and 22%, respectively. High salt concentration and very low wastewater temperature were possible reasons for these unexpectedly low P and TIN removal efficiencies. In contrast, removal rates of bacteria (Escherichia coli, enterococci) and organic matter (as BOD) were high, due to filtration in the alkaline medium Polonite^® (Ecofiltration Nordic AB, Stockholm, Sweden) and the fine sand used as SBCW substrate. High pH in effluent from the PTP was efficiently reduced to below pH 9 in the SBCW, meeting recommendations by environmental authorities in Sweden. We concluded that treating cold on-site wastewater can impair treatment performance and that technical measures are needed to improve SBCW performance. Full article

Use of reactive filter media (RFM) is an emerging technology in small-scale wastewater treatment to improve phosphorus (P) removal and filter material longevity for making this technology sustainable. In this study, long-term sorption kinetics and the spatial dynamics of sorbed P distribution were simulated in replaceable P-filter bags filled with 700 L of reactive material and used in real on-site treatment systems. The input data for model calibration were obtained in laboratory trials with Filtralite P^®, Polonite^® and Top16. The P concentration breakthrough threshold value was set at an effluent/influent (C/C₀) ratio of 1 and simulations were performed with P concentrations varying from 1 to 25 mg L⁻¹. The simulation results showed that influent P concentration was important for the breakthrough and longevity, and that Polonite performed best, followed by Top16 and Filtralite P. A 100-day break in simulated intermittent flow allowed the materials to recover, which for Polonite involved slight retardation of P saturation. The simulated spatial distribution of P accumulated in the filter bags showed large differences between the filter materials. The modelling insights from this study can be applied in design and operation of on-site treatment systems using reactive filter materials. Full article

This paper aims to examine the potential of permeable reactive barriers (PRBs) as an in-situ removal approach for phosphate polluted agricultural runoff. Four different reactive materials (RMs) of: autoclaved aerated concrete (AAC), Polonite^®, zeolite and limestone were tested. The study was conducted as a column experiment with a sandy loam soil type charging underlying RM layers with phosphorus (P) and a soil column without RM as a reference. The experiment was carried out over 90 days. During this time the P-PO₄ load from the reference column equaled 6.393 mg and corresponds to 3.87 kg/ha. Tested RMs are characterized by high P-PO₄ retention equaling 99, 98, 88 and 65% for Polonite^®, AAC, zeolite and limestone, respectively. At common annual P loss rates of 1 kg/ha from intensively used agricultural soils, the PRB volume ranged from 48 to 67 m³ would reduce the load between 65 and 99% for the RMs tested in this study. Full article

Using a filter medium for organic matter removal and nutrient recovery from blackwater treatment is a novel concept and has not been investigated sufficiently to date. This paper demonstrates a combined blackwater treatment and nutrient-recovery strategy and establishes mechanisms for a more dependable source of plant nutrients aiming at a circular economy. Source-separated blackwater from a student dormitory was used as feedstock for a sludge blanket anaerobic-baffled reactor. The effluent from the reactor, with 710 mg L⁻¹ NH₄–N and 63 mg L⁻¹ PO₄–P, was treated in a sequence of upflow and downflow filtration columns using granular activated carbon, Cocos char and polonite as filter media at a flow rate of 600 L m⁻² day⁻¹ and organic loading rate of 430 g chemical oxygen demand (COD) m⁻² day⁻¹. Filtration treatment of the anaerobic effluent with carbon adsorbents removed 80% of the residual organic matter, more than 90% of suspended solids, and turbidity while releasing more than 76% NH₄–N and 85% of PO₄–P in the liquid phase. The treatment train also removed total coliform bacteria and E. coli in the effluent, achieving concentrations below detection limit after the integration of ultraviolet (UV) light. These integrated technological pathways ensure simultaneous nutrient recovery as a nutrient solution, pathogen inactivation, and reduction of active organic substances. The treated nutrient-rich water can be applied as a source of value creation for various end-use options. Full article