Biochar from co-pyrolysis of biological sludge and woody waste followed by chemical and thermal activation: end-of-waste procedure for sludge management and biochar sorption efficiency for anionic and cationic dyes.

Nine biochars were produced by co-pyrolysis of sawdust and biological sludge following the "design of experiment" approach. Two kinds of sludge (both deriving from the treatment of mixed industrial-municipal wastewater) and two types of woody waste were selected as categorical predicting variables, while contact time, pyrolysis temperature, and sludge percentage were used as quantitative variables. Biochars were analysed for their product characteristics and environmental compatibility based on the European Standards (EN 12915-1:2009) for materials intended for water treatment (i.e. ash content, water leachable polycyclic aromatic hydrocarbons (PAHs) and elements), as well as for specific surface area (SSA), using them as response variables of a multivariate partial least square multiple regression, whose results provided interesting insights on the relationships between pyrolysis conditions and biochar characteristics. Biochars produced with sludge and/or providing the highest SSA values (258-370 m2 g-1) were selected to undergo a sustainable chemical treatment using a by-product of the gasification of woody biomass, complying in all cases with European Standards and achieving therefore the end-of-waste status for sewage sludge. The biochar deriving from the highest percentage of sludge (30% by weight) and with the highest SSA (390 m2 g-1) was thermally activated achieving SSA of 460 m2 g-1 and then tested for the sorption of direct yellow 50 and methylene blue in ultrapure water and real wastewater, compared to a commercial activated carbon (AC). The biochar showed Langmuir sorption maxima (Qm) 2-9 times lower than AC, thus highlighting promising sorption performances. Qm for methylene blue in wastewater (28 mg‧g-1) was confirmed by column breakthrough experiments.

Water safety plans and risk assessment: A novel procedure applied to treated water turbidity and gastrointestinal diseases.

Water Safety Plans (WSPs), as recommended by the World Health Organization (WHO), can help drinking water suppliers to identify potential hazards related to drinking water and enable improvements in public health outcomes. In this study we propose a procedure to evaluate the health risk related to turbidity in finished water by determining the cases of drinking water-related gastrointestinal diseases. The results of several epidemiological studies and three-year time series turbidity data, coming from three different drinking water treatment plants (WTPs) located in Tuscany (Italy), have been used to determine the relationship between drinking water turbidity and gastroenteritis incidence and to assess the health risk attributable to the turbidity of tap water. The turbidity variation occurring in the treated water during the monitored period showed an incremental risk compared to the baseline value from 9% to 27% in the three WTPs. Risk reduction due to each treatment step was also evaluated and it was found that a complete treatment train (clari-flocculation, sand filtration, activated carbon filtration and multi-step disinfection) reduces risk by over 600 times. Our approach is a useful tool for water suppliers to quantify health risks by considering time series data on turbidity at WTPs and to make decisions regarding risk management measures.

Occurrence of selected pharmaceuticals in wastewater treatment plants of Tuscany: An effect-based approach to evaluate the potential environmental impact.

Municipal wastewaters may pose a risk to the aquatic environment and ultimately to human kind. Their treatment is a fundament step but the actual WWTPs performances cannot be taken for granted, claiming instead for continuous evaluation campaigns. Our waters are indeed threatened by the continuous input of various persistent micropollutants that are part of human daily routine life; the potential effects of their presence in the receiving waters have to be quantified. The present paper reports data of a monitoring campaign focused on nine pharmaceuticals belonging to different therapeutic groups in three WWTPs in Tuscany (Italy). All the three WWTPs use conventional activated sludge process with pre-denitrification and no tertiary treatment. The analytical determination has been achieved through off-line solid phase extraction and analysis in liquid chromatography coupled with mass spectrometry. The overall ecotoxicological effect of effluents was evaluated through a battery of tests using organisms belonging to different trophic levels. All nine pharmaceuticals were detected in the influent of all WWTPs at least in one sampling campaign. The most concentrated compounds were acetaminophen, diclofenac and amoxicillin followed by atenolol, ketoprofen, clarithromycin, carbamazepine, doxycycline and E2; their average concentrations (considering all measurements from all plants) were, respectively: 3914 ±â€¯2620; 2065 ±â€¯739; 2002 ±â€¯2170; 1223 ±â€¯1042; 961 ±â€¯1003; 356 ±â€¯370; 233 ±â€¯100; 196 ±â€¯189; 4 ±â€¯4 ng/L. The highest concentrations were found in the plant that treats urban and hospital wastewaters. Amoxicillin, atenolol and diclofenac were more concentrated in winter than in summer, while ketoprofen, doxycycline and 17-ß-estradiol are higher in summer. These results are probably due to the different consumption of each drug during the year, depending on their therapeutic usage. Measured drugs can be divided into three categories: those ones that are generally well removed inside the WWTP (such as acetaminophen, ketoprofen and atenolol), the partly removed ones (doxycycline, clarithromycin and 17-ß-estradiol) and the refractory ones to biodegradation during activated sludge process (carbamazepine, diclofenac and amoxicillin). Regarding ecotoxicological assays, the most sensitive organisms were V. fisheri and R. subcapitata, whereas D. magna almost never reacted to the wastewaters. Seasonal variability was not clearly observed among plants and collecting time. The toxicity score evaluated all the results coming from the bioassays battery, indicating that WWTPs treatments always determined a toxicity reduction, even though a residual toxicity was still measured. This observation, together with chemical data, clearly indicate WWTPs as an important source of pharmaceuticals in the Arno river with an important environmental toxicity; therefore, the reduction of pharmaceutical load originated from point source such us WWTPs would ask in the future the adoption of refinery steps in WWTPs able to increase RE of drugs.