Performance of an On-Site Wastewater Treatment System Using Reactive Filter Media and a Sequencing Batch Constructed Wetland

Phosphate adsorption from water and wastewater using non-devulcanised and devulcanised tyre rubber

The secondary use of tyre rubber is a potentially sustainable environmental solution. However, the sorption properties of used-tyre rubber have not yet been fully investigated. In this study, the rubber type (vulcanised or devulcanised part-worn tyre rubber) that can sorb phosphate phosphorus from aqueous solutions or wastewater more effectively is determined. The capacity of granules (0.3-1.0 mm in diameter) of non-devulcanised ground tyre rubber and uniquely chemically devulcanised rubber to adsorb phosphorus is evaluated under laboratory conditions. The results show that under the filtration of an aqueous solution or biologically treated wastewater at a flow rate of 0.75 m/h (1.2 L/h), 1 g of the devulcanised rubber medium accumulates 5.16 mg of phosphorus, which is five times more than that accumulated by the non-devulcanised rubber medium. The surface structure of the non-devulcanised rubber medium is more suitable for the sorption of devulcanised rubber granules. The sorption capacity and effectiveness of non-devulcanised rubber for phosphorus removal are more favourable compared with those of the tested natural and waste-prepared sorbents. Further research into this material as a medium for filter layers and for accumulating drainage should be conducted. The findings of this study are important for addressing issues associated with the secondary use of tyre rubber.

Integrated Methods for Household Greywater Treatment: Modified Biofiltration and Phytoremediation

Most countries around the world have experienced water scarcity in recent decades as fresh water consumption has increased. However, untreated wastewater is routinely discharged into the environment, particularly in developing countries, where it causes widespread environmental and public health problems. The majority of wastewater treatment method publications are heavily focused on high-income country applications and, in most cases, cannot be transferred to low and middle-income countries. An experimental study was conducted to evaluate the performance efficiency of pilot-scale physicochemical and biological treatment methods for the treatment of household greywater in Jimma, Ethiopia. During the experiment, grab samples of greywater were taken from the combined treatment system's influent and effluent every 7 days for 5 weeks and analyzed within 24-48 hours. Temperature, DO, EC, turbidity, TDS, and pH were measured on-site, while BOD, COD, TSS, TP, TN PO₄ ^-3-P, NO₃-N, NH₄-N, Cl^-, and FC were determined in the laboratory. During the five-week pilot-scale combined treatment system monitoring period, the combined experimental and control system's mean percentage reduction efficiencies were as follows: turbidity (97.2%, 92%), TSS (99.2%, 97.2%), BOD₅ (94%, 57.4%), COD (91.6%, 54.7%), chloride (61%, 35%), TN (68.24, 42.7%), TP (71.6%, 38.7%), and FC (90%, 71.1%), respectively. Similarly, the combined experimental and control systems reduced PO₄ ^-3-P (12.5 ± 3 mg/L), NO₃-N (4.5 ± 3 mg/L), and NH₄-N (10.19 ± 2.6 mg/L) to PO₄ ^-3-P (3.5 ± 2.6 mg/L, 7.5 ± 1.6 mg/L), NO₃-N (0.8 ± 0.5, 3.6 ± 2.3 mg/L), and NH₄-N (7 ± 2.9 mg/L, 15.9 ± 3.9 mg/L), respectively. From the biofiltration and horizontal subsurface flow constructed wetland combined systems, the experimental combined technology emerged as the best performing greywater treatment system, exhibiting remarkably higher pollutant removal efficiencies. In conclusion, the combined biofiltration and horizontal subsurface flow constructed wetland treatment system can be the technology of choice in low-income countries, particularly those with tropical climates.

Long-term phosphorus sorption and leaching in sand filters for onsite treatment systems

The sorption capacities of sand filters used for onsite wastewater treatment and their associated risks of phosphorus (P) leaching on contact with rainwater were investigated in column experiments and with modelling tool for over 300 days. Columns packed with sand were exposed to real domestic wastewater of different characteristics and hydraulic loading modes. The wastewater fed into the columns was effluent collected from three different treatment units in the field: a septic tank (ST), biofiltration tank (BF) and Polonite® filter bag (PO). The risk of P leaching to groundwater and surface water was also assessed, by exposing the same sand columns to natural rainwater. Overall results indicated that sand soils can exhibit different adsorption and desorption capacities for electrical conductivity (EC), Total-P, phosphate-P and total suspended solids, depending on the characteristics of influent wastewater, loading rate and total operation time. The removal efficiencies of the sand columns increased in the order ST (98.16%) > PO (93.36%) > BF (81.57%) for PO4-P and slightly decreased ST (97.11%) > PO (92.06%) > BF (76.76%) for Total-P columns. All sand columns loaded with actual wastewater solutions from septic tanks and biofiltration tank have demonstrated high risks of phosphorus leaching (>99.99%) to the groundwater. The modelling was successful captured behavior of EC tracer and adsorption of PO₄-P with acceptable prediction uncertainty in the PO < 8% columns. The modelling results indicated that the decrease of loading rate from 83.3 mL d-1 to 20.83 mL d-1 led to an average increase of removal efficiency and prolong operational lifetime and mass of adsorbed Total-P in the sand soil. This study concludes that sand is a valuable filter medium at low loading rate for phosphorus removal in full-scale operations of onsite treatment systems, however very vulnerable for leaching P when in contact with rainwater.

Research and Modelling the Ability of Waste from Water and Wastewater Treatment to Remove Phosphates from Water

This research investigated the ability of two materials, which are waste generated during water treatment and wastewater treatment, to remove phosphates from water. The selected materials were quartz sand used in drinking water treatment plants (OQS) and incinerated (600 °C) sewage sludge (ISS). The materials were chosen for their composition: both contain aluminium, iron, and calcium. The experiments were carried out in the laboratory (in batch and in columns stand). Modelling of the sorption processes was performed on the basis of results from experiments in batches. The maximum adsorption capacity of the OQS was 1.14 mg/g obtained using the linearized Langmuir model and the maximum adsorption capacity of the ISS was 0.86 mg/g for the linearized Langmuir model (in batch). A pseudo-first-order model obtained using a nonlinear fit can accurately explain phosphate adsorption kinetics using both adsorbents: OQS and ISS. During the column filtration experiment, a higher sorption capacity of the ISS filter media was achieved −2.1 mg of phosphate phosphorus per gram of filter media. The determined adsorption capacity of the investigated materials was average, but the reuse of this waste would help to solve the issues of the circular economy.

Sand from groundwater treatment coated with iron and manganese used for phosphorus removal from wastewater

This article presents investigations into the removal of PO₄-P from biologically treated wastewater using raw material taken from drinking water treatment filters - quartz sand grains coated with iron and manganese oxide coating (OG). The experiments carried out in laboratory stands used real household wastewater and demonstrated that OG filter media accumulated and removed from wastewater two times more PO₄-P than known reactive filter media Filtralite P. The mean effectiveness of PO₄-P removal from wastewater by filtering at a rate of 2.2 m/h and using OG filter media reached 68%. The pH of the filtrate from OG filter media was stable and reached 7.7 ± 0.2 thus meeting requirements for the discharge of treated wastewater into the natural environment. OG grains are mechanically resistant, do not pollute the filtrate and could therefore be used as filter media for tertiary wastewater treatment.

Assessment of the Efficiency, Environmental and Economic Effects of Compact Type On-Site Wastewater Treatment Plants—Results from Random Testing

This study presents the results of random testing of selected on-site wastewater treatment plants (WWTPs) constructed in Poland in Masovia Voivodship in the years 2011–2016. The vast majority of tested on-site WWTPs were compact (container) type treatment plants, based on low rate activated sludge (AS), sequencing batch reactors (SBR), or a hybrid (activated sludge supported with biological film, AS + BF) method. Compact type plans are becoming more and more popular in single households in Poland, due to the option of co-financing. According to certificates provided by producers and distributors, container on-site wastewater treatment plants are efficient in BOD5 removal, with the expected removal rate being over 80%. The aim of this study was (1) to analyze BOD5 in effluents sampled from randomly selected on-site WWTPs, (2) to evaluate predicted and real environmental effects of the implementation of on-site WWTPs in selected communes within Masovia Voivodship, and (3) to calculate unit environmental and economic effects of container on-site WWTPs in three different technologies. Results of this study show that in most cases, there is a gap between the declared and the real BOD5 removal efficiency. There is also a difference between the performance of different container type technologies. The lowest real environmental effect was obtained for AS technology, and the highest for the hybrid one. The predicted environmental effect has only been almost achieved in the case of hybrid systems. Based on net present value (NPV) benefits, technologies can be set up as follows: AS > SBR > AS + BF, making the AS method the most effective technology from the point of view of the economy.