The digestate produced from anaerobic treatment of agricultural biomasses and zootechnical effluents presents a high load of organic and ammonia nitrogen. European directive limits spreading on soils of these substances, considered polluting in high concentration. Without a sufficient size of agricultural land is then necessary a treatment for nitrogen removal at the aim of agronomic reuse of treated water. The process, composed of several technologies, enables not only recycling of water, but also recovery of by-products, usable as soils fertilizers or improvers, and production of a hygienized and stabilized compost.

    Wastewater of production cycles of fruit juices, beer, wine and liquors contains biodegradable substances as sugars and alcohol. The treatments more advisable for depuration of effluents of this sector are biological ones. Performances of processes can be improved thanks to combination of aerobic technologies to anaerobic ones. The best solution in case of small spaces is the MBR (Membrane Bio-Reactor), that joins aerobic oxidation to membrane filtration: treated water is dischargeable according to the law or recyclable in working process and concentrate, if it has a suitable quality level, can be used as soil improver.

    Wastewater of chemical and pharmaceutical industries has generally an abundant amount of COD, surfactants, acids and fluorides, substances that can be removed by physico-chemical, biological and evaporation treatments. Evaporators for purification of effluents of these industrial fields are built in stainless steel or metal alloys or in silicon carbide, materials that can assure a high resistance to corrosion exerted by acids. Addition of an ultrafiltration section allows the recovery of solution, recyclable in production process.

    Water employed for human consumptions and for civil activities has to respect specific safety standards. The assurance of water drinkability is guaranteed by filtration, chemical disinfection (chlorination, ozonation), UV rays sterilization. Also waters of public pools, hotels, spa, thermal and medical centres have to be subjected to treatments of ultrafiltration, multimedia filtration, disinfection with UV, ozone and other chemicals for reduction of pollutants and removal of pathogens. Application of innovative technologies enables furthermore abatement and prevention of Legionella bacteria.

    Wastewaters of food industry stand out for high contents of organic substances (as sugars, carbohydrates, starches, proteins) or salts. The first ones, rich of COD (Chemical Oxygen Demand), are efficaciously purified by biological processes, as UASB (Upflow Anaerobic Sludge Blanket), MBR (Membrane Bio-Reactors), SBR (Sequencing Batch Reactors), that eliminate pollutants through digestion of carbon. The biogas yielded during the treatment can be employed as energy source. The best system for saline solutions purification is the evaporation, able to produce until to 70-90% of distilled water and to 30-10% of concentrate. The creation of vacuum in ebullition chamber and the use of multiple effects systems guarantee energy efficiency of plant, lowering operating costs.

    Processes of paper production need a primary water without hardness or with low salinity, obtainable with softening and desalination treatments. Wastewaters hold suspended solids, COD, BOD and salts, that can be taken off by application of biological technologies, as the UASB, and physico-chemical processes, as flotation. The procedure for melting of lignin, furthermore, produces the black liquor, contaminated from chemical substances, that can be treated with evaporation technology: concentrate can sometimes be recycled or valorized as secondary raw material.

    Working process of petrochemical industry generates effluents with suspended solids, mineral oils and other hydrocarbons. For removal of these pollutants are needed separation treatments. Due the high concentration of noxious substances in these wastewaters, the more advisable choice from environmental point of view is “zero liquid discharge”: operating costs are reduced thanks to the total recycling of water in production process and recovery of by-products of treatment.

    Several industrial fields need treated water for input in production cycles. In particular, food, electronic, chemical, pharmaceutical and cosmetic industries require ultrapure water – that is with a high conductivity and without bacterial load – for use as ingredient in products formulation. Between applications that permit to obtain it, there are ion exchange, for calcium and magnesium removal; deionization, able to eliminate until to 100% of salts; reverse osmosis, that, as well as desalinates water, retains pathogens and pesticide; ultrafiltration, with membranes able to hold suspended solids, viruses and bacteria.

    Access to public purifiers for discharge of sewage is often limited from opening times and flood of tank trucks. Installation of a treatment plant on site results in economical benefit for enterprises specialized in sewers and septic tanks emptying, as allows to shorten duration of interventions. The process, composed of different sections, removes from wastewater oils, heavy metals, suspended solids and COD. Thanks to employ of physico-chemical treatment, in addition to biological one, water can be recycled for washing of vans and areas designated to discharge, with a further reduction of operating costs.

    Contaminated sites are areas in that, following the carrying out of industrial activities, the quality of soils and of surface and ground waters has been altered from polluting substances in concentrations higher than those forecasted by law. Remediation interventions require aspiration of liquids from soil or, in case of high pollution levels, removal and washing of soil. Treatment of contaminated water can of consequence be done in plants installed on site or in the establishments of companies specialized in soils washing. In the first case it is possible opt for mobile units, also with possibility of rental.

    In the process waters of working of metal surfaces – as galvanizing, varnishing, anodizing – are in general present high polluting substances, as heavy metals, phosphates, acidic and alkaline solutions, surfactants, oils and organic compounds, that can be removed only through combination of several technologies, between that evaporation, filtration, ion exchange. Due the possibility that remains of contaminants stay in treated water, “zero liquid discharge” systems, allowing a total recovery of water in production cycle, represent the more reliable solution in this field.

    Urban waste dropped off at landfill generates drippings and leachate having physico-chemical characteristics variable on the basis of typology of waste and of environmental conditions. In general, these effluents hold heavy metals, COD, chlorides, sulfates and other substances as nitrogen, nitrates, ammoniac, boron. Their treatment requires the combination of different technologies, as evaporation, membrane filtration, ion exchange. Leachate rich in COD can be treated with biological technology UASB, able to yield biogas thanks to process of organic substances digestion. From digestate produced from anaerobic treatment of organic fraction of waste, furthermore, can be obtained compost and by-products usable as fertilizers.