Long-term operation of a novel electrically-enhanced biomass concentrator reactor for wastewater treatment.

Membrane biological reactors (MBRs) are a key technology in wastewater treatment nowadays. However, due to their high construction cost and energetic requirements, alternatives based on the same principle of biomass retention have been designed and operated. Amongst these, biomass concentrator reactors (BCRs), using a coarser filter medium instead of a membrane, have shown to be able to remove a wide range of contaminants from wastewater and groundwater. A new BCR-derived technology enhanced with an electric field, called the electrically-enhanced biomass concentrator reactor (E2BCR), was designed and tested for urban wastewater treatment at different organic loads for a period of 180 days. The electrically-enhanced reactor showed better chemical oxygen demand (COD) removal performances than a non-enhanced control reactor (92.4% and 83.6% respectively) thanks also to electrocoagulation effects, and a lower fouling tendency, and proved to be more energy efficient in comparison with the control reactor in terms of energy consumption per mass of COD removed.

Effects of process operating conditions on the autotrophic denitrification of nitrate-contaminated groundwater using bioelectrochemical systems.

Nitrates have been detected in groundwater worldwide, and their presence can lead to serious groundwater use limitations, especially because of potential health problems. Amongst different options for their removal, bioelectrochemical systems (BESs) have achieved promising results; in particular, attention has raised on BES-driven autotrophic denitrification processes. In this work, the performance of a microbial electrolysis cell (MEC) for groundwater autotrophic denitrification, is assessed in different conditions of nitrate load, hydraulic retention time (HRT) and process configuration. The system obtained almost complete nitrate removal under all conditions, while nitrite accumulation was recorded at nitrate loads higher than 100mgNO3-L-1. The MEC system achieved, in different tests, a maximum nitrate removal rate of 62.15±3.04gNO3--Nm-3d-1, while the highest TN removal rate observed was 35.37±1.18gTNm-3d-1. Characteristic of this process is a particularly low (in comparison with other reported works) energy consumption: 3.17·10-3±2.26·10-3kWh/gNO3-N removed and 7.52·10-2±3.58·10-2kWhm-3 treated. The anolyte configuration in closed loop allowed the process to use less clean water, while guaranteeing identical performances as in other conventional configurations.

Direct measurement of nutrient concentrations in freshwaters with a miniaturized analytical probe: evaluation and validation.

This work deals with the evaluation of the aqueous concentrations of dissolved reactive phosphorus (DRP), total phosphorus (TP), and ammonium nitrogen (N-NH4) in surface water by means of direct online instrumentation. A portable, submersible, and automated analyzer designed to measure dissolved and total nutrient concentrations characterized by miniaturization of the entire analytical process was tested against laboratory methods. A total number of 36 water samples of different origin (i.e., rain, river, lake, and sewage waters) were analyzed and used in the comparison of DRP, TP, and N-NH4 data. Raw data were distributed in a broad range of concentrations: 5-299 µg P/L for DRP, 7-97 µg P/L for TP, and 11-332 µg N/L for N-NH4. Regression analysis underlined a high significant correlation between the measures of the probe and those of the laboratory (0.6 < R 2 < 0.9; p < 0.001) and pointed out the effectiveness of the new instrument in representing a broad range of nutrient concentrations.

Microbial fuel cells for direct electrical energy recovery from urban wastewaters.

Application of microbial fuel cells (MFCs) to wastewater treatment for direct recovery of electric energy appears to provide a potentially attractive alternative to traditional treatment processes, in an optic of costs reduction, and tapping of sustainable energy sources that characterizes current trends in technology. This work focuses on a laboratory-scale, air-cathode, and single-chamber MFC, with internal volume of 6.9 L, operating in batch mode. The MFC was fed with different types of substrates. This study evaluates the MFC behaviour, in terms of organic matter removal efficiency, which reached 86% (on average) with a hydraulic retention time of 150 hours. The MFC produced an average power density of 13.2 mW/m(3), with a Coulombic efficiency ranging from 0.8 to 1.9%. The amount of data collected allowed an accurate analysis of the repeatability of MFC electrochemical behaviour, with regards to both COD removal kinetics and electric energy production.

Accounting for water quality effects of future urbanization: diffuse pollution loads estimates and control in Mantua's lakes (Italy).

The three shallow lakes of Mantua (Upper, Middle and Lower) formed by the Mincio River are today classified by Italian water authorities as sensitive areas, after, in the second half of the 20th century, the hydrologic regime of the lakes was heavily modified, and the influence of industrial activities operating in the 1960s--without much environmental consideration--created a substantial decline in the water quality of the lakes. The City of Mantua is one of the most vital industrial centers of Northern Italy, and development plans are under way, that should approximately double the extension of the urban and industrial area within the next 20 years. This paper deals with estimating the effects of the aforementioned urbanization on the future water quality of the three lakes.

Field monitoring and evaluation of innovative solutions for cleaning storm water runoff.

Urbanization increases the variety and amount of pollutants transported to receiving waters. Sediment from development and new construction; oil, grease, and toxic chemicals from automobiles; nutrients and pesticides from turf management and gardening; viruses and bacteria from failing septic systems; road salts; and heavy metals are examples of pollutants generated in urban areas. Sediments and solids constitute the largest volume of pollutant loads to receiving waters in urban areas. When runoff enters storm drains, it carries many of these pollutants with it. In older cities, this polluted runoff is often released directly into open waterways without any treatment. Increased pollutant loads can harm fish and wildlife populations, kill native vegetation, foul drinking water supplies, and make recreational areas unsafe. The objective of the study, performed by University of Pavia (Italy), University of Brescia (Italy) and GreenTechTexas International (US), reported herein is to evaluate the use of an innovative stormwater technology (EcoDräin) to reduce pollution due to urban runoff in existing urban areas. The paper describes the methodology and the results achieved with tests conducted in laboratory in Pavia University in Italy and in two pilot areas in Italy and in Australia to investigate the EcoDräin's effectiveness for oil and heavy metals retention and sediment trapping. In the tests performed in a marina near Sydney in Australia a reduction has been achieved in oil and grease concentration higher than 95% and a reduction in metal concentration (particularly Copper, Lead and Zinc) close to 98%. The paper also describes the methodology of the analysis on the absorbing material after its use and the consequent determination of the most efficient and environmentally safe way to dispose of consummated absorbent.

Assessing the environmental impact of WWTP expansion: odour nuisance and its minimization.

As part of the effort to provide proper wastewater disposal for the City of Milan, the expansion of the WWTP located in Peschiera Borromeo has been planned and is currently under completion. The plant, sized for a population of less than 300,000, will soon treat the wastes from the south-east areas of Milan for a total capacity of over 500,000 p.e. The paper describes the approach to find a satisfactory solution of an alleged odour problem that is slowing down the completion of the plant restructuring. This included a survey of the existing plant and analysis of its final design, identification of odour emission sources and their quantification, and the examination of different alternatives for odour abatement. These were carried out using air quality modelling techniques consisting of dynamic, continuous "puff" models capable of reproducing diffusion even at very low pollutant concentrations. Several intervention hypotheses were tested and compared with the few existing regulatory norms and guidelines for odour pollution. In all but the minimum and the no-action hypotheses, proposed actions would results in a drastic reduction of nuisance effects at the receptors. Under the strongest intervention hypothesis (the one adopted by the WWTP agency), odour impact would be virtually eliminated.