Frederick Bloetscher

Application of photochemical technologies for treatment of landfill leachate

Because of widely varying practices in solid waste management, an all-inclusive solution to long-term management of landfill leachate is currently not available. There is a major technological need for sustainable, economical options for safe discharge of leachate to the environment. Two potential on-site pretreatment technologies, photochemical iron-mediated aeration (PIMA) and TiO(2) photocatalysis were compared for treatment of landfill leachate at laboratory scale. Results of bench scale testing of real landfill leachate with PIMA and TiO(2) photocatalysis showed up to 86% conversion of refractory COD to complete mineralization, up to 91% removal of lead, up to 71% removal of ammonia without pH adjustment, and up to 90% effective color removal with detention times between 4 and 6h, in field samples. The estimated contact times for 90% removal of COD, ammonia, lead, and color were found to be on the order of 10-200 h for PIMA and 3-37 h for TiO(2) photocatalysis. Testing with actual leachate samples showed 85% TiO(2) photocatalyst recovery efficiency with no loss in performance after multiple (n>4 uses). Pre-filtration was not found to be necessary for effective treatment using either process.

Comparative assessment of municipal wastewater disposal methods in Southeast Florida

A comparative assessment of the risks of three effluent disposal alternatives currently available to wastewater utilities in Southeast Florida is presented in this paper. The alternatives are: deep well injection and ocean outfalls following secondary treatment, and surface water (canal) discharges following secondary wastewater treatment, filtration and nutrient removal. Water quality data, relative to disposal of wastewater treatment plant effluent were gathered, along with water quality data on the receiving waters, from utilities. Comparisons and conclusions regarding potential health concerns associated with the three disposal alternatives are presented. The results indicated that health risks associated with deep wells were generally lower than those of the other two alternatives. The proximity of injection wells to aquifer storage and recovery wells was a determining factor relative to injection well risk. Urban ecological risks were also indicated to be lower, though impacts of urban water use/reuse to the Everglades were not studied. Additional data collection and analysis were recommended to understand the effects of wastewater management on the cycling of water, nutrients and other constituents on southeast Florida. In particular, it was recommended that monitoring of effluents for nitrosamines and pharmaceutically active substances be implemented on a broad scale.

Net-zero water management: achieving energy-positive municipal water supply

Net-zero water (NZW) is a new vision for municipal water management, in which significant water is neither imported to, nor exported from the service area, i.e. local water independence. While such a system has long been possible in areas of sufficient water supply and/or sparse population, it is now becoming possible and economical for municipal systems in virtually any modern watershed, through the use of emerging direct potable reuse (DPR) technology. In fact, current implementations are producing design and operating data. Moreover, distributed NZW systems recycling at a high rate are projected to be capable of energy-positive operation, saving more domestic hot water energy than is consumed in treatment. However, NZW and DPR approaches vary widely in terms of source water, source segregation, treatment, and recycling rate. In this study, a workshop was convened to assemble and synthesize a broad cross-section of current NZW and DPR experience, to develop recommendations for water management planning. It was concluded that technology is currently emerging to support widespread NZW management. Recommendations included the introduction of NZW systems into new construction, to be supported by controlled demonstration projects over periods of two years or more; development of supporting regulatory structure with public engagement; development of real-time water quality monitoring devices; and retention of the term “net-zero water” to signify a new water management vision to advance water and energy autonomy.

Environmental Review & Case Study: Evaluating the Significance of Certain Pharmaceuticals and Emerging Pathogens in Raw Water Supplies

Pharmaceuticals and personal care products (PPCPs) are environmental contaminants introduced by the activities of man. PPCPs are not new or emerging from the perspective of knowing about them, but they are of growing interest due to reports in the popular media on occurrence and environmental impacts. As a result, PPCPs may be deemed as emerging issues by the public and utilities. Likewise, the biological constituents are not new—but, for reasons that are unclear, certain ones appear to pose a greater risk to consumers today than they have in the past. Similarly, Cryptosporidium parvum did not appear to pose a risk until 400,000 people became ill, and approximately 100 people died of cryptosporidiosis in Milwaukees water service area in 1993. Today, regulators and public health scientists are trying to identify microbes that pose a similar risk in the future. If these constituents occur in raw water supplies, they may need monitoring and treatment prior to these waters entering the potable water distribution system. The Contaminant Candidate List (CCL) developed by United States Environmental Protection Agency outlines a series of biological contaminants of concern that are not currently regulated but may pose a threat. Should these contaminants move from the CCL to a regulatory framework, water supply utilities will incur added monitoring and testing of their water supply sources, and potentially added monitoring and treatment costs in their operations.

Evaluation of coastal ocean discharges and environmental impacts in southeast Florida.

This article outlines the current literature regarding anthropogenic inputs of nutrients and microorganisms into the coastal oceans. The concern about nutrients and microorganisms in coastal marine waters is that they may cause a shift in local populations of organisms and encourage invasive algae and coral diseases. The lack of baseline data on marine populations makes it difficult to determine the source of marine population shifts. This report focuses on the question of whether there is sufficient data to implicate coastal ocean outfall discharges of secondary treated wastewater effluent in southeast Florida as a causative agent in impacts to coastal communities. The literature does not appear to support evidence of population shifts from any particular source.

Salinity mapping for Florida bay using Landsat TM images and in-situ observations

The salinity of Florida Bay has been increasing for decades due to anthropogenic interventions and natural disturbances of natural sheetflow through the Everglades and adjacent natural systems. Yet little data has been gathered and geospatially analyzed. This study developed a set of multivariate hydro-spatial statistical models to predict the dry and wet season surface salinity concentrations in Florida Bay. The modeling was carried out using in-situ salinity observations from USGS for 2004–2006, and processed Landsat TM 4–5 images for the closest 21 days. To improve the accuracy, the study area was clustered in 3 sub-regions leading to 6 cases (3 sub-regions ∗ 2 seasons). The statistical model produced R2 values ranging from 0.53 to 0.83, which are acceptable considering the large size and geographic complexity of the study domain. The two salinity maps created for the Florida Bay area provide a visual representation of the temporal and spatial variation between seasons.

Using Multiple Tracers to Evaluate Coastal Water Quality Impacts for Sewered and Non-Sewered Areas

When onsite treatment and disposal systems (OSTDS) are not properly sited or installed, they can be a potential risk to public health and a source of environmental degradation. There are estimated to be over 2.3 million onsite sewage treatment and disposal systems currently in use in Florida, serving approximately 4.5 million people. These systems discharge over 426 million gallons of treated effluent per day in to the subsurface soil environment. Nearly 40% of those systems are found along Floridas southeastern Atlantic coastline. Onsite system failure can result in problems that include direct exposure to inadequately treated sewage, ground and surface water pollution, and contamination of shellfish beds. Throughout the State of Florida, where the water table is high, septic tanks have proven to be problematic from a water resource perspective. Impacts are traced to a lack of regulation prior to the 1980s and to high densities of septic tanks on small lots. Moreover, many of these high-density developments were historically inhabited only in the winter months when the water table is low and performance optimal. When the water table is high, septic tanks cannot operate properly because the water table is above the drainage pipes, interfering with the normal hydraulic specifications and complicating pollutant migration modeling. Thus, the potential for groundwater and surface water contamination is increased, and clearly there is a need to quantify the contribution of environmental degradation attributable to OSTDS. The research team has investigated differences in sewered and non-sewered areas in Broward and Palm Beach Counties in Florida to attempt to quantify the nutrient loading contribution from septic tanks and also to determine the extent of observed nutrient contamination from other sources in a major urban setting. Recently, a unique opportunity to study a rural area in Taylor County, allowed the research team to investigate newer tracers. Taylor County (see Figure 1) is located in Northwest Florida along the Gulf of Mexico coastline directly south of Tallahassee. The total area of the County is 789,000 acres (3,191 km 2 ), of which approximately 15% is comprised of water bodies. Taylor County has four rivers, numerous canals, creeks, and springs, and nearly 60 miles of Gulf of Mexico coastline. The major tourist attractions are fishing and scalloping, particularly from July through September. Half of its southern coast is part of the Big Bend Sea Grasses Aquatic Preserve and is classified as Outstanding Florida Waters . Prior studies have been conducted by the Suwanee River Water Management District (SRWMD) and the Taylor County Health Department (TCHD) in Taylor County to determine if water quality criteria are being met. An ongoing beach monitoring program posts advisories approximately 46% of the time due to high concentration of indicator bacteria (>400 CFU/100mL for fecal coliform, >100 CFU/100mL for Enterococcus ). Maintenance of the microbiological quality and safety of water systems used for drinking, for recreation, and for the harvesting of seafood is imperative. Contamination of these water systems can result in high risks to human health and significant economic losses due to closures of beaches and shellfish harvesting areas.