Inhibitory effects of veterinary antibiotics on anammox activity: short- and long-term tests

The suitability of the anammox process for the treatment of swine digester liquor was assessed through the evaluation of the short- and long-term inhibitory effect of three veterinary antibiotics commonly administered to Italian swine livestock. The toxicity of doxycycline, tiamulin and enrofloxacin was evaluated through batch tests designed to estimate specific anammox activity. Moreover, the short-term toxicity of combined concentrations of doxycycline and enrofloxacin was evaluated so as to verify whether a synergistic effect could be established. According to the inhibition recorded in the presence of the maximum antibiotics concentrations predicted for digester liquor, target compounds do not seem to represent a real hazard for anammox bacteria because at those concentration levels, the activity was just slightly reduced. Moreover, in granular systems, inhibition could be easily counterbalanced by increasing the biomass concentration in the reactor, thus assuring the design treatment capacity for antibiotic-rich wastewaters.

Membrane filtration and sonication for industrial wastewater reuse

This paper presents an experimental study aimed at estimating the efficiency of the innovative process of ultrafiltration (UF) combined with sonication (Son.) for the refinement of treated effluent to be reused in wet textile processes. Such a novel approach, which has not yet been employed on a full industrial scale, has been experienced at pilot scale on the secondary effluent of the Baciacavallo wastewater treatment plant (WWTP), which treats part of the effluent from one of the largest textile industry districts in Italy. The combined treatment efficiency was assessed both on ozonated and non-ozonated Baciacavallo secondary effluent. The membrane filtration process was optimized in terms of running time, backwash, chemical addition and cleaning procedures. The sonication treatment was optimized on laboratory-scale with synthetic solutions (demineralized water added with dyestuffs) in terms of hydroxyl radicals formation rate, frequency, acoustic power, hydrogen peroxide addition, contact time and pH. The optimal conditions have been applied on the pilot-scale sonicator which was used in combination with the UF treatment. According to the experimental results, the best configuration within the Baciacavallo WWTP was the sonication of non-ozonated wastewater followed by the UF. The combined treatment guaranteed the compliance with the target values for wastewater reuse in wet textile industries. This study is part of the Research Project PURIFAST (Purification of industrial and mixed wastewater by combined membrane filtration and sonochemical technologies) LIFE + ENV/IT/000439.

Experimental study on municipal and industrial reclaimed wastewater refinement for agricultural reuse

The present study is aimed at verifying the possibility of reusing municipal and industrial reclaimed wastewaters for the irrigation of container-grown ornamental shrubs, paying attention to the refinery treatment. The research has been carried out in the district of Pistoia (Central Italy), which represents one of the main nursery areas in Europe. Two experimental sites, each consisting of a refinery treatment pilot plant (filtration and disinfection) and an agronomic area, were set-up. In this paper the attention is focused on the selection of the refinery treatment. The combined process of peracetic acid (PAA) and ultraviolet irradiation (UV) chosen for the disinfection treatment proved to be very effective for the inactivation of microorganisms for both municipal and industrial wastewaters. The high efficiency is recognised as being brought about by the formation of free radicals due to the photolysis of the PAA when in the presence of the UV rays. A preliminary cost analysis has been carried out in order to highlight the most economically advantageous solution which guarantees the compliance to the Italian limits for wastewater reuse in agriculture (Escherichia Coli 10 CFU/100 mL).

Olive mill wastewater biological treatment by fungi biomass

Olive oil extraction is one of the most important traditional food industries in the Mediterranean region, especially in Italy. In addition to olive oil, this industry produces by-products, in particular olive mill wastewaters (OMWs) and olive husks, which represent a serious environmental problem. OMWs can be rarely treated in a municipal WWTP, using conventional wastewater treatments. A novel biological process has to be considered in order to treat OMWs. Literature data show that yeasts and different kinds of fungi are able to reduce both the organic and the phenolic content of the OMW. The present work is aimed at investigating the growth of a biomass rich in fungi in a batch reactor filled with OMW and its capacity to degrade the organic and phenolic load. The aerobic OMW degradation obtained using this biomass reached a COD and TP removal efficiency of 86 and 70%, respectively. Respirometric tests have been carried out in order to measure the biomass activity on different substrates: OMW and phenolic compounds (gallic and p-coumaric acids). The polyphenolic biodegradation efficiency of fungi biomass was higher than the one of a non-acclimated activated sludge biomass. Fungi biomass was able to completely degrade pure phenolic compounds.

Oxidative processes for olive mill wastewater treatment

The present work describes an experimental study carried out in order to investigate the efficiency and feasibility of physical (lime coagulation) and advanced oxidation processes (Ozone and Fenton's process) for olive oil mill wastewater treatment. Particular attention was paid to the degradation of both organic and phenolic compounds. Lime coagulation reaches maximum removal at a pH of 12, with a TP (total polyphenols) and COD reduction of 37 and 26%, respectively. Ozone oxidation is also pH-dependent, showing the higher removal efficiency (91% for TP and 19% for COD) with an initial pH value of 12. Experimental results show a lower efficiency of Fenton's process than ozone in TP removal, reaching a maximum value of 60%. Oxidation trials carried out on gallic and p-coumaric synthetic solutions confirmed ozone and Fenton's efficiency at degrading phenolic compounds. Biological trials, both aerobic and anaerobic, highlighted a significant increase of biodegradability of treated OMW samples if compared to the untreated ones. Respirometric tests showed an increase in BOD of about 20% and anaerobic batch tests provided a methane production up to eight times higher.

MBR pilot plant for textile wastewater treatment and reuse

An experimental study was carried out in order to evaluate the possibility of upgrading the conventional activated sludge WWTP of Seano (Prato, Italy) which treats municipal and textile wastewaters, by using membrane bioreactor (MBR) technology. The MBR pilot plant, set up within Seano WWTP, was fed with mixed municipal-industrial wastewaters during the first experimental period and with pure industrial wastewaters during the second. Performances and operation of the MBR were evaluated in terms of permeate characteristics and variability (COD, colour, surfactants, total N and P) and other operational parameters (sludge growth and observed yield). According to the experimental results the MBR permeate quality was always superior to the Seano WWTP one and it was suitable for industrial reuse in the textile district of the Prato area. Respirometric tests provided a modified IWA ASM1 model which fits very well the experimental data and can be used for the design and the monitoring of a full-scale MBR pilot plant.

Olive mill wastewater treatment: an experimental study

Olive oil production, one of the main agro-industries in Mediterranean countries, generates significant amounts of olive mill wastewaters (OMWs), which represent a serious environmental problem, because of their high organic load, the acidic pH and the presence of recalcitrant and toxic substances such as phenolic and lipidic compounds (up to several grams per litre). In Italy, traditional disposal on the soil is the most common way to discharge OMWs. This work is aimed at investigating the efficiency and feasibility of AOPs and biological processes for OMW treatment. Trials have been carried out on wastewaters taken from one of the largest three-phase mills of Italy, located in Quarrata (Tuscany), as well as on synthetic solutions. Ozone and Fenton's reagents applied both on OMWs and on phenolic synthetic solutions guaranteed polyphenol removal efficiency up to 95%. Aerobic biological treatment was performed in a batch reactor filled with raw OMWs (pH = 4.5, T = 30 degrees C) without biomass inoculum. A biomass rich of fungi, developed after about 30 days, was able to biodegrade phenolic compounds reaching a removal efficiency of 70%. Pretreatment of OMWs by means of oxidation increased their biological treatability.