Case study: A GPR survey on a morainic lake in northern Italy for bathymetry, water volume and sediment characterization

We carried out an extensive waterborne GPR survey consisting of 50 profiles with a total length of nearly 37 km on the morainic lake of Candia northerly Turin (Italy). Our aim was to test the capability of GPR to estimate the bathymetry, the water volume and the sediment type. We enhanced and controlled the GPR data processing and interpretation with bathymetry acquired with an acoustic echo sounder and measured conductivity and temperature profile of the water column with a multiparametric probe. We also analyzed the diffraction hyperbola that originated within the sediments in order to estimate the velocity and relative permittivity. With the permittivity and dielectric mixing rules, we estimated the porosity of the sediments above the diffracting objects and drew a map of the bottom lake porosit

Factors affecting phosphorus recovery as struvite: Effects of alternative magnesium sources

Phosphorus depletion around the globe has made it a critical element for sustainable agriculture resulting in significant research into options to recover and recycle this non-renewable resource. Phosphorus recovery as struvite usually requires the dosing of supplemental commercial magnesium and can account for between 10 and 75% of the cost of struvite production. Therefore, cheaper alternatives to commercial magnesium sources such as seawater and concentrates from RO desalination plants have been sought. Here, we examine the effects of alternative magnesium sources on the phosphorus removal efficiency, particle size, rate constant, morphology and purity of struvite precipitated from synthetic solutions. It was found that the phosphorus removal reduced for struvite precipitation using seawater (14%) compared to the control (29%), but increased for struvite precipitation using bittern (37%). Precipitation using seawater also increased the calcium content from <0.1% for the control and bittern to 6.6% and reduced the average particle size from 88 μm for the control to 50 μm for seawater and to 67 μm for bittern in 1 L jar tests. Batch reactor tests indicate that both magnesium sources produced struvite, though the particle size was smaller for trials using alternative magnesium sources which may limit the efficiency of solid-liquid separation

Neither alone nor neglected: the elderly in a 19th-century Italian city

The environmental benefits and burdens of phosphorus recovery in four centralized and two decentralized municipal wastewater systems were compared using life cycle assessment (LCA). In centralized systems, phosphorus recovered as struvite from the solids dewatering liquid resulted in an environmental benefit except for the terrestrial ecotoxicity and freshwater eutrophication impact categories, with power and chemical use offset by operational savings and avoided fertilizer production. Chemical-based phosphorus recovery, however, generally required more resources than were offset by avoided fertilizers, resulting in a net environmental burden. In decentralized systems, phosphorus recovery via urine source separation reduced the global warming and ozone depletion potentials but increased terrestrial ecotoxicity and salinization potentials due to application of untreated urine to land. Overall, mineral depletion and eutrophication are well-documented arguments for phosphorus recovery; however, phosphorus recovery does not necessarily present a net environmental benefit. While avoided fertilizer production does reduce potential impacts, phosphorus recovery does not necessarily offset the resources consumed in the process. LCA results indicate that selection of an appropriate phosphorus recovery method should consider both local conditions and other environmental impacts, including global warming, ozone depletion, toxicity, and salinization, in addition to eutrophication and mineral depletion impacts

Environmental Benefits and Burdens of Phosphorus Recovery from Municipal Wastewater

The environmental benefits and burdens of phosphorus recovery in four centralized and two decentralized municipal wastewater systems were compared using life cycle assessment (LCA). In centralized systems, phosphorus recovered as struvite from the solids dewatering liquid resulted in an environmental benefit except for the terrestrial ecotoxicity and freshwater eutrophication impact categories, with power and chemical use offset by operational savings and avoided fertilizer production. Chemical-based phosphorus recovery, however, generally required more resources than were offset by avoided fertilizers, resulting in a net environmental burden. In decentralized systems, phosphorus recovery via urine source separation reduced the global warming and ozone depletion potentials but increased terrestrial ecotoxicity and salinization potentials due to application of untreated urine to land. Overall, mineral depletion and eutrophication are well-documented arguments for phosphorus recovery; however, phosphorus recovery does not necessarily present a net environmental benefit. While avoided fertilizer production does reduce potential impacts, phosphorus recovery does not necessarily offset the resources consumed in the process. LCA results indicate that selection of an appropriate phosphorus recovery method should consider both local conditions and other environmental impacts, including global warming, ozone depletion, toxicity, and salinization, in addition to eutrophication and mineral depletion impacts

Effect of water conservation and recycling on the potential for, and environmental impact of, phosphorus recovery from municipal wastewater in Australia

Per capita water consumption declined by 25-36% while recycled water use increased by 10% in Australian capital cities from 2000 to 2009. Assuming constant per capita phosphorus loads, these changes present an opportunity for phosphorus recovery as struvite from RO brine generated at water recycling plants. A multi-parametric model for a 50,000 equivalent population wastewater recycling plant found specific power for struvite recovery from RO brine reduced from 590 to 170 kWh/kgP as per capita water consumption declined from 300 to 50 L/c/d. Phosphonate antiscalants used in RO systems at a typical concentration of 30 mg/L reduced the phosphorus removal efficiency from 29% to 20% for phosphorus recovery from synthetic solutions and altered the rhombic struvite precipitate in 1L jar tests. However, the effects were less pronounced in a 5L batch reactor at higher struvite saturation (SI 1.8), indicating the technical feasibility of struvite recovery from RO brine. An alternative magnesium source, seawater, reduced the phosphorus removal efficiency from 29% for the control to 14%, while the use of bittern increased the removal to 37% in 1L jar tests. The use of seawater also increased the calcium content of the precipitate from <0.1% for the control and bittern to 6.6% and altered the rhombic structure in 1L jar tests, though the effects were less pronounced in a 5L batch reactor. While technically feasible, analysis of wastewater catchments with declining water consumption over the 2000 to 2012 period found per capita phosphorus loads declined in 11 of 12 catchments, indicating that on an energy basis, phosphorus recovery from the RO brine is unlikely to compare with production from mined phosphate rock. A life cycle analysis comparing the environmental benefits and burdens of introducing phosphorus recovery into existing infrastructure found struvite recovery from solids dewatering streams was preferred over recovery from RO brine and over direct land application of biosolids at centralised plants. Urine separation reduced the global warming and ozone depletion potentials of decentralised systems, although the soil salinization and terrestrial ecotoxicity potentials increased. While avoided fertilizer provided benefits, it didn’t necessarily outweigh the resources required to achieve phosphorus recovery

Supporting the implementation of drinking water management systems in New South Wales, Australia

Since 2010, New South Wales (NSW) Health has assisted local water utilities to develop and implement risk-based drinking water management systems based on the Australian Drinking Water Guidelines Framework for Management of Drinking Water Quality. This support has benefited regional communities, and especially smaller utilities, by helping to identify and control risks. NSW Health's support projects have resulted in statistically significant improvements across many elements of drinking water management system implementation. Through this program of support, NSW Health has identified possible infrastructure and operational needs and assessed implementation of drinking water management systems. In parallel, NSW Health has worked to assess the risk from Cryptosporidium in drinking water supplies and to develop a formal audit program. Findings from the NSW Health support program informed the development of two NSW Government programs and the commitment of more than $1 billion to help local water utilities address public health and other critical needs. The introduction of risk-based drinking water management systems has driven incremental improvement in drinking water quality management across the state of NSW. HIGHLIGHTS NSW Health supports regional water utilities implement risk-based drinking water management systems.; Standardised questionnaires are used to demonstrate statistically significant improvements in implementation.; Outputs coded into a database and assigned risk ratings to prioritise further support.; Priorities for support inform investment in infrastructure.; Incremental improvements seen in water quality management.