- The River Segura: reclaimed water, recovered river
- Authors: M. A. Ródenas; M. Albacete
Abstract: The Region of Murcia is located in southeast Spain, an area known for structural water stress. The most important water source that runs through the Region is the Segura River, which is the main irrigation water resource. Late last century there was a significant environmental problem in the Segura River caused by an increase of inadequately treated wastewater discharges, in a period of low flow rates and intensive use of water resources. The situation reached such a critical point, that the Regional Government presented a General Plan for Wastewater Reclamation, to be developed in 10 years. This paper details the content and guidelines in the Plan, as well as aspects related to policy development and objective achievement: water availability has increased and the Segura River conditions have improved. In short, it can be concluded that wastewater reclamation marks a good starting point for bettering water management in arid areas. Furthermore, the case of the Region of Murcia reveals that comprehensive action lines and optimized engineering and knowledge of wastewater management is highly beneficial.
- Improving biological phosphorus removal in membrane bioreactors – a
- Authors: S. Smith; G. Kim, L. Doan H. Roh
Abstract: With increasing water reuse applications and possible stringent regulations of phosphorus content in secondary and tertiary effluent discharge in Florida, USA, alternative technologies beyond conventional treatment processes require implementation to achieve low phosphorus (P) and nitrogen (N) concentrations. A pilot scale membrane bioreactor (MBR) system, operated in Florida, adopted the University of Cape Town (UCT) biological process for the treatment of domestic wastewater. The system operated for 280 days at a wastewater treatment facility with total hydraulic retention time (HRT) of 7 h and sludge retention time (SRT) of 20 days. Operating conditions were controlled to maintain specific dissolved oxygen (DO) concentrations in the reactors, operate at suitable return activated sludge (RAS) rates and to waste from the appropriate reactor. This process favored biological phosphorus removal and achieved 94.1% removal efficiency. Additionally, chemical oxygen demand (COD) and N removal were achieved at 93.9% and 86.6%, respectively. Membrane operation and maintenance did not affect the biological P removal performance but enhanced the process given the different operating requirements compared to that required with the conventional UCT process alone. Conclusively, the result of the pilot study demonstrated improvement in biological phosphorus removal. The UCT-MBR process tested achieved average effluent nitrogen and phosphorus concentrations of 5 mg/L as N and 0.3 mg/L as P.
- Seawater desalination using forward osmosis process
- Authors: Parida Venketeswari; Ong Say Leong Ng How Yong
Abstract: This study aims to evaluate the feasibility of the forward osmosis (FO) process for seawater desalination. The leakage of boron from the seawater into the draw solution was also studied. According to the WHO guideline, the maximum permissible limit of boron in drinking water is 2.4 ppm. Preliminary results of boron rejection by forward osmosis membrane were found to be 60–70%. Minimal fouling of the FO membrane was observed in the experimental run spanning over 70 days. Under the given set of test conditions, flux of 1.4 L m−2h−1 was found throughout the run and there was no significant decline in the flux. With a flux recovery of 40% which is the same as that of the reverse osmosis (RO) process, FO could be potentially utilized for seawater desalination applications.
- Effects on macronutrient contents in soil-plant irrigated with different
quality waters and wastewaters
- Authors: M. T. Orta de Velásquez; K. Velázquez Pedroza, I. Yáñez-Noguez, I. Monje-Ramírez A. E. Campos-Reales-Pineda
Abstract: The goals of this research were focused on investigating the effects of irrigation with untreated wastewater, ozone-enhanced primary treated wastewaters (O3EPTW), tap water and tap water + fertilizer on the macronutrient content in soil and plant tissues. The effect on plant development was evaluated by growing Lactuca sativa in soils irrigated with these different quality waters and wastewaters, and by determining the macronutrients content in water, soil and plants. In this study, the soils irrigated with O3EPTW showed increased organic matter concentrations, which is advantageous for crop cultivation. The electric conductivity for the O3EPTW irrigated soils remained below those of the tap water + fertilizer and untreated wastewater. The soil irrigated with tap water + fertilizer showed a marked decrease in pH, and its long-term use could lead to soil acidification. Macronutrient levels in plant tissues (N, K and Mg contents) were similar for all irrigation waters, except for tap water which always remained lower than the others. It was concluded that the use of O3EPTW may become a good irrigation alternative that can be employed without the health risks associated with the use of untreated wastewaters, also reducing the adverse effects on soil's salinity or acidification.
- Comparative assessment of managed aquifer recharge versus constructed
wetlands in managing chemical and microbial risks during wastewater reuse:
- Authors: A. F. Hamadeh; S. K. Sharma G. Amy
Abstract: Constructed wetlands (CWs) and managed aquifer recharge (MAR) represent commonly used natural treatment systems for reclamation and reuse of wastewater. However, each of these technologies have some limitations with respect to removal of different contaminants. Combining these two technologies into a hybrid CW-MAR system will lead to synergy in terms of both water quality and costs. This promising technology will help in the reduction of bacteria and viruses, trace and heavy metals, organic micropollutants, and nutrients. Use of subsurface flow CWs as pre-treatment for MAR has multiple benefits: (i) it creates a barrier for different microbial and chemical pollutants, (ii) it reduces the residence time for water recovery, and (iii) it avoids clogging during MAR as CWs can remove suspended solids and enhance the reclaimed water quality. This paper analyzes the removal of different contaminants by CW and MAR systems based on a literature review. It is expected that a combination of these natural treatment systems (CWs and MAR) could become an attractive, efficient and cost-effective technology for water reclamation and reuse.
- The transport of three emerging pollutants through an agricultural soil
irrigated with untreated wastewater
- Authors: Juan C. Durán-Álvarez; Yamani Sánchez, Blanca Prado Blanca Jiménez
Abstract: The aim of this work was to determine the mobility of naproxen, carbamazepine, and triclosan through a wastewater-irrigated agricultural soil. Transport experiments were carried out using undisturbed soil columns taken at 10 and 40 cm depths. The mobilization of the pollutants was evaluated using two hydrological regimes transient flow for superficial columns and steady-state conditions for the sub-superficial columns. Results demonstrated that preferential flows are present in the superficial soil, and transient flow conditions facilitate the movement of the pollutants through the soil. Conversely, displacement of the contaminants in the sub-superficial soil columns was slower than that observed in the superficial soil. Triclosan was not found in the leachates of the soil columns at the two depths, indicating the strong retention of the compound by the soils. Conversely, naproxen and carbamazepine were determined in leachates of the soil columns at both depths. Retardation in the transport of carbamazepine was higher than that observed for naproxen in the two tested soils. Naproxen and triclosan showed some degree of dissipation, while carbamazepine was recalcitrant. It was concluded that the natural depuration system studied is capable of retaining and removing the studied pollutants and thus the risk of groundwater pollution is minimized.
- Sustainable water management with multi-quality recycled water production:
the example of San Luis Potosi in Mexico
- Authors: Valentina Lazarova; Lucina Equihua Alberto Rojas
Abstract: This paper presents and discusses the performance, reliability of operation, socio-economic and environmental aspects and benefits of the Tenorio Project in San Luis Potosi. This is the first project in Mexico making possible the production of multi-quality recycled water for planned water reuse for different purposes, including industrial cooling in a power plant, agricultural irrigation, groundwater restoration and environmental enhancement. Long-term water quality monitoring demonstrated the reliability of operation of the selected treatment trains, which were well adapted to local conditions and the given reuse application. The major challenge was the control of the conductivity and silica content in recycled water for industrial reuse, which needed complementary investigations and the implementation of an additional treatment by ion exchange. The reliable operation of the power plant with recycled water encouraged other industries to explore water reuse as an option, as well as the possibility of improved treatment. Once the main technical and social challenges of the original project were overcome, the project acquired a new dimension with the request of the industrial client to improve water quality by means of reverse osmosis. In return, the power plant proposed giving their right for water withdrawal from the aquifer to the City of San Luis Potosi, allowing thus the availability of freshwater for augmentation of the potable water supply.