Environmental Life Cycle Assessment of Hydrothermal Carbonization of Sewage Sludge and Its Products Valorization Pathways

ABSTRACT

This study is aimed at evaluating through Life Cycle Assessment (LCA) the environmental performances of an integrated system of an existing Water Resources Recovery Facility (WRRF) and a hypothetical hydrothermal carbonization (HTC) plant applied to the generated sewage sludge (SS). Beside the valorisation of the solid product (hydrochar, HC) as a fuel substituting lignite, the possibility to valorize also the liquid fraction (process water, PW) derived by the HTC, by anaerobic digestion to produce biogas, is here proposed and analysed. Additionally, phosphorus recovery from HC, prior its use, by acid leaching with nitric acid is also suggested and evaluated. Thus, four integrated scenarios, based on SS carbonization, are proposed and compared with the current SS treatment, based on composting outside of the WRRF (Benchmark scenario). The proposed scenarios, based on HTC, show improved performances with respect to the benchmark one, for thirteen of sixteen considered impact indicators. For the Climate Change (CC) indicator, the two HTC scenarios are able to reduce the impacts up to - 98%, with respect to the Benchmark. Further, the introduction of anaerobic digestion of PW proves to reduce impacts more than other configurations in eleven on sixteen impact categories. On the contrary, the introduction of phosphorus recovery process negatively affects the values for most of indicators. Thus, possible solutions to improve the integration of this process are outlined (e.g., the use of sulfuric acid instead of nitric one, or the application of a different ratio between solid and acidified solution during acid leaching of HC to recover phosphorus).

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12649-022-01821-x.

Ozonation effects for excess sludge reduction on bacterial communities composition in a full-scale activated sludge plant for domestic wastewater treatment

Activated sludge process is the most widely diffused system to treat wastewater to control the discharge of pollutants into the environment. Microorganisms are responsible for the removal of organic matter, nitrogen, phosphorous and other emerging contaminants. The environmental conditions of biological reactors significantly affects the ecology of the microbial community and, therefore, the performance of the treatment process. In the last years, ozone has been used to reduce excess sludge production by wastewater treatment plants (WWTPs), whose disposal represents one of the most relevant operational costs. The ozonation process has demonstrated to be a viable method to allow a consistent reduction in excess sludge. This study was carried out in a full-scale plant treating municipal wastewater in two parallel lines, one ozonated in the digestion tank and another used as a control. Bacterial communities of samples collected from both lines of digestion thanks were then compared to assess differences related to the ozonation treatment. Data were then analysed with terminal restriction fragment length polymorphism (T-RFLP) analysis on 16S rRNA gene. Differences between bacterial communities of both treated and untreated line appeared 2 weeks after the beginning of the treatment. Results demonstrated that ozonation treatment significantly affected the activated sludge in WWTP.

A modified Activated Sludge Model to estimate solids production at low and high solids retention time

In this paper, a modified version of the IWA-ASM1 model capable of correctly simulating the production of solids over a wide range of solids retention time (SRT) is presented. The parameters of the modified model have been estimated by integrating the results of respirometric and titrimetric tests with those of studies conducted on pilot scale plants that treat industrial wastewaters of differing characteristics. On the basis of the experimental results and their subsequent processing, it appears that the production of solids may be satisfactorily estimated using the modified model in which fractions X(P) and X(I) are supposed to be hydrolysable with a first-order kinetic. In the cases that were examined, the constant of the aforementioned kinetics was estimated to be k(i)=0.012 d(-1) and k(i)=0.014 d(-1), for tannery and textile wastewater respectively. A reliable calibration of the parameter k(i) was possible when data relative to the experiment conducted in the pilot plants for no less than 60 d and in conditions of complete solid retention was utilized.

The role of tannins in conventional and membrane treatment of tannery wastewater

The role that tannins play in tannery wastewater treatment has been evaluated employing a pilot Membrane Bioreactor (MBR) plant and a full scale Conventional Activated Sludge Process (CASP) plant conducted in parallel. The proposed methodology has established the preliminary use of respirometry to examine the biodegradability of a selection of commercial products (synthetic and natural tannins); the subsequent analysis, by means of spectrophotometric reading and RP-IPC (Reverse-Phase Ion-Pair) liquid chromatography, estimates the concentrations of natural tannins and naphthalenesulfonic tanning agents in the influent and effluent samples. The results show that a consistent percentage of the Total Organic Carbon (TOC) in the effluent of the biological phase of the plants is attributable to the presence of natural and synthetic (Sulfonated Naphthalene-Formaldehyde Condensates, SNFC) tannins (17% and 14% respectively). The titrimetric tests that were aimed at evaluating the levels of inhibition on the nitrifying biomass samples did not allow a direct inhibiting effect to be associated with the concentration levels of the tannin in the effluent. Nonetheless, the reduced specific growth rates of ammonium and nitrite oxidising bacteria imply that a strong environmental pressure is present, if not necessarily due to the concentration of tannins, due to the wastewater as a whole. The differences that have emerged by comparing the two technologies (CASP and MBR), in regards to the role that tannins play in terms of biodegradability, did not appear to be significant.

Characterization of tannery wastewater and biomass in a membrane bioreactor using respirometric analysis

Respirometric techniques and an activated sludge model (ASM) were applied for the characterization of tannery wastewater and biomass in a pilot plant membrane bioreactor (MBR) operating at high sludge age. The traditional respirometric tests and the IWA-ASM1 were modified to take into account the specific operating conditions, the solid-liquid separation technology and the wastewater complexity. As a result the wastewater biodegradable COD was fractionated into four components: readily biodegradable, rapidly hydrolysable, slowly hydrolysable and inorganic (due to the presence of reduced sulphur compounds). The kinetic and stoichiometric parameters of the biomass (heterotrophic and nitrifying) were estimated through the integration of model simulations and respirometric tests results. In particular the ammonium and nitrite-oxidizing biomasses were separately characterized: the growth kinetics of ammonium and nitrite-oxidizing bacteria resulted noticeably lower than the traditional reference values (mu(max,AOB)=0.25d(-1)e mu(max,NOB)=0.23d(-1) at 20 degrees C, respectively). The ASM was finally used to confirm that the results of the wastewater and biomass characterization allow to properly simulate the mixed liquor suspended solids in the MBR pilot plant and the COD concentration in the effluent.

Reuse of industrial wastewater for the irrigation of ornamental plants

This paper describes the results of experimental activities carried out for verifying the possibility of reusing reclaimed wastewater originated from textile (70%) and domestic (30%) activities for the irrigation of container-grown ornamental shrubs. Aspects that concern the refinery treatment of reclaimed wastewater and the effect of irrigation on some ornamental plant species were investigated. An experimental site consisting of a refinery treatment pilot plant (filtration and disinfection) and an agronomic experimental area was set-up. The combined treatment of PAA and UV, used for the disinfection, showed to be very effective for inactivation of E. coli with most of PAA and UV dose combinations able to assure total inactivation. The plants (Buxus, Photinia, Pistacia and Viburnum), sprinkle and drip irrigated with well water (WW), reclaimed wastewater (RW) and a water mixed (MW) between reclaimed wastewater and well water (1:1 by vol), showed interesting results. A similar growth among different treatments was achieved for Buxus and Pistacia, while Viburnum and Photinia plants showed a higher sensibility to MW and RW. Photinia, in particular, turned out to be very sensitive to sprinkle irrigation with the reclaimed water, while the drip irrigation had no such bad effects, as reported in previous works.

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).

Membrane bio-reactor for textile wastewater treatment plant upgrading

Textile industries carry out several fiber treatments using variable quantities of water, from five to forty times the fiber weight, and consequently generate large volumes of wastewater to be disposed of. Membrane Bio-reactors (MBRs) combine membrane technology with biological reactors for the treatment of wastewater: micro or ultrafiltration membranes are used for solid-liquid separation replacing the secondary settling of the traditional activated sludge system. This paper deals with the possibility of realizing a new section of one existing WWTP (activated sludge + clariflocculation + ozonation) for the treatment of treating textile wastewater to be recycled, equipped with an MBR (76 l/s as design capacity) and running in parallel with the existing one. During a 4-month experimental period, a pilot-scale MBR proved to be very effective for wastewater reclamation. On average, removal efficiency of the pilot plant (93% for COD, and over 99% for total suspended solids) was higher than the WWTP ones. Color was removed as in the WWTP. Anionic surfactants removal of pilot plant was lower than that of the WWTP (90.5 and 93.2% respectively), while the BiAS removal was higher in the pilot plant (98.2 vs. 97.1). At the end cost analysis of the proposed upgrade is reported.

Reclaimed municipal wastewater as source of water and nutrients for plant nurseries

A three year experimental activity was carried out to evaluate the possibility of reusing Reclaimed Wastewater (RWW) in Pistoia's nursery area (Central Italy). The research was aimed at: 1. identifying the best tertiary treatment facilities in order to make the effluent in compliance with the current Italian legislation for RWW reuse, 2. evaluating the effects of RWW irrigation on some ornamental, 3. quantifying fertilizing value and environmental impacts of RWW irrigation. In this paper the results of the last year experimental activity are presented. Experimental results indicated that filtration and disinfection with peracetic acid plus UV were very effective in indicator bacteria removal; as a matter of fact, neither Escherichia coli nor Total Coliforms were detected in any samples of pilot plant effluent. Results of an agronomical experiment indicated the suitability of the tertiary effluent for the irrigation: at the end of the growing season a higher (or equal) total dry mass was detected in RWW irrigated plants than well-water (WW) irrigated ones. Finally, the tertiary effluent can be considered as an important source of fertilizer for container-grown plants. As a matter of fact RWW irrigation showed to be able to replace at least one of the traditional fertilization treatments.

Membrane bio-reactor for advanced textile wastewater treatment and reuse

Textile wastewater contains slowly- or non-biodegradable organic substances whose removal or transformation calls for advanced tertiary treatments downstream Activated Sludge Treatment Plants (ASTP). This work is focused on the treatment of textile industry wastewater using Membrane Bio-reactor (MBR) technology. An experimental activity was carried out at the Baciacavallo Wastewater Treatment Plant (WWTP) (Prato, Italy) to verify the efficiency of a pilot-scale MBR for the treatment of municipal wastewater, in which textile industry wastewater predominates. In the Baciacavallo WWTP the biological section is followed by a coagulation-flocculation treatment and ozonation. During the 5 months experimental period, the pilot-scale MBR proved to be very effective for wastewater reclamation. On average, removal efficiency of the pilot plant (93% for COD, 96% for ammonium and 99% for total suspended solids) was higher than the WWTP ones. Color was removed as in the WWTP. Anionic surf actants removal of pilot plant and WWTP were very similar (92.5 and 93.3% respectively), while the non-ionic surfactants removal was higher in the pilot plant (99.2 vs. 97.1). In conclusion the MBR technology demonstrated to be effective for textile wastewater reclamation, leading both to an improvement of pollutants removal and to a draw-plate simplification.

HIDE: a new hybrid environment for the design of custom-made hip prosthesis

This technical note describes a new software environment (HIPCOM design environment, HIDE) for the design of custom-made total hip replacements. These devices are frequently designed using general-purpose mechanical computer-aided design (CAD) programs using a set of bone contours extracted from the computer tomography (CT) images as anatomical reference. On the contrary, the HIDE system was developed to let the operator directly design the stem shape onto the CT images in a single-step operation. The operator can directly import CT data in DICOM format or use special functions to reconvert to a digital stack, the CT images printed on a radiological film. Once the stack of CT images is loaded, the operator can design the implant shape by imposing control sections directly on the CT images. The interpolation of these control sections produces the basic 3D shape of the custom-made stem. The shape is then exported to the CAD-computer-aided manufacturing (CAM) program to refine the design and to generate the part program to manufacture the implant with a CNC tooling machine. Using HIDE, the duration of design steps it affected was reduced by more than 50% with respect to the standard method in use at the manufacturer site. HIDE also improved the accuracy and the repeatability of the whole procedure. The learning curve became flat after only ten cases. These good results were achieved because of the integration of the vectorial description of the prosthetic component with the raster description of the CT data that allowed the designer to use all details available in the CT images.

Development of a software for the design of custom-made hip prostheses using an open-source rapid application development environment

The present work describes a technology transfer project called HIPCOM devoted to the re-engineering of the process used by a medical devices manufacturer to design custom-made hip prostheses. Although it started with insufficient support from the end-user management, a very tight scheduling and a moderate budget, the project developed into what is considered by all partners a success story. In particular, the development of the design software, called HIPCOM Interactive Design Environment (HIDE) was completed in a time shorter than any optimistic expectation. The software was quite stable since its first beta version, and once introduced at the user site it fully replaced the original procedure in less than two months. One year after the early adoption, more than 80 custom-made prostheses had been designed with HIDE and the user had reported only two bugs, both cosmetics. The scope of the present work was to report the development experience and to investigate the reasons for these positive results, with particular reference to the development procedure and the software architecture. The choice of TCL/TK as development language and the adoption of well-defined software architecture were found to be the success key factors. Other important determinants were found to be the adoption of an incremental software engineering strategy, well suited for small to medium projects and the presence in the development staff of a technology transfer expert.

Effect of Reclaimed Wastewater on the Growth and Nutrient Content of Three Landscape Shrubs

An experiment was set up to determine the effects of treated municipal wastewater irrigation and fertilization on growth, leaf morphological characteristics, chlorophyll content, and ion uptake of three container-grown landscape shrubs characterized by different growth habits (Abutilon ‘Kentish Belle’, Viburnum tinus ‘French White’, Weigelia florida ‘Bouquet Rose’). The study was conducted in Tuscany (Central Italy) in a typical landscape plant production area. One-hundred plants per species were watered with treated sewage effluent from the nearby wastewater treatment facility (RW) and 100 with well water after ponding (WW) from the nursery where the research plots were located. Fifty plants per species and within each irrigation treatment received controlled-release fertilizer application at transplant and 50 received no fertilization. The experiment showed no major limitations to the use of sprinkle-irrigated wastewater for container-grown landscape plant production and a general, positive, influence on growth of the plants. However, the species under observation showed a different behavior in response to the effluent irrigation for all the parameters considered. Weigelia was the most responsive and Abutilon the least. The influence of fertilizer addition at transplanting was less evident and the combined effect of RW and fertilization was rarely found and seemed to be species-specific.

Skin contamination and low airborne nickel exposure of electroplaters

The present study was performed to evaluate the role of hand and facial contamination in the absorption of soluble nickel compounds in 41 male subjects employed in electroplating operations in 25 small factories in the province of Florence (Italy). Personal exposure to airborne nickel ranged from 0.10 to 42 micrograms/m3; the median (range) urine, hands and face nickel levels were 4.2 (0.7-50) micrograms/l, 39 (1.9-547) micrograms, 9.0 (1.0-86) micrograms, respectively. Face nickel values explained the bulk of the variance in urine nickel levels (42%). In stepwise multiple regression analysis all other variables were not significant. The log-linear model can be expressed as: log (urine-Ni) = 0.295 + 0.593 log (face-Ni). Our results suggest that skin contamination, especially facial skin, plays an important role in nickel absorption in exposed workers.

[The space of passion]

The figures and speech of passion are clinically polymorphous and heterogeneous: from the baroque of the mystical ecstasy, the iconophily of religious and political ideologies, the collector's usual fetishism and the paranoiac insanity of hatred to the passions of knowing and loving. These are at the same time a passion for life as well as for self-destruction, for showing oneself as well for not knowing oneself, for representing oneself as well as for non representing oneself. Passion bares the impossible of mourning, its real point that gives a boost to the continual work. Passion confronts us to the essence of the being, to its fundamental distress. The being, whose shadow is projecting itself on the object of the passion, gives a name and a face to that object, and receives back its marks. That explains why passion is always accompanied by suffering. Moreover, passion is suffering according to its etymology: until the XVIth century, the word "passionate" meant somebody who suffered physically. The nature of the object of the passion (a relic, a part of a sentence, an indication, the track of an object or any other subject) changes nothing to the structure of the speech of passion.

Respiratory disorders and lung function impairment in pyrite miners

A research study was carried out at a pyrite mine in Niccioleta, southern Tuscany, during the period 1980-1983 to investigate the possible effects of gaseous and particulate pollutants on the respiratory function of mine workers. The study was undertaken to fill the gap in recent scientific information in this field and also collect data which could be used for future planning of epidemiological and environmental controls at the mine. For the most exposed underground workers a dust exposure of 1.04 mg/m3 of inhalable dust and 0.60 mg/m3 of respirable dust was found. The average quartz content was less than 1.5% in both types of dust. Median exposures of the most exposed risk group were 6.0 ppm for carbon monoxide (CO), 0.22 ppm for nitrogen dioxide (NO2), 0.09 ppm for sulfur dioxide (SO2). The health effects of gaseous and particulate pollutants were studied by comparing the respiratory symptoms and lung function data of the miners with those of a reference group. A significantly increased prevalence of simple chronic bronchitis was found among underground miners when compared to the reference group. This condition was not associated with functional impairment of obstructive nature. Chest x-rays revealed 14 cases of p type pneumoconiosis.

Pulmonary alveolar lipoproteinosis in rats following intratracheal injection of pyrite particles

Wistar rats were injected intratracheally with pyrite particles and after 6 and 12 mo, lungs were evaluated for histological changes. Results were compared with rats that were given particles of galena, lead silicate, travertine, and quartz. Under the light microscope no significant changes were observed in the lungs from animals treated with galena, lead silicate, and travertine. In the lungs from animals that received quartz, a typical nodular fibrosis was observed. Moreover, both pyrite-treated rats and quartz-treated rats developed pulmonary alveolar lipoproteinosis; the lesions were much less prominent and severe in animals injected with pyrite than with quartz. These results indicate that pyrite, like only a few other types of dust that are different from quartz, can evoke the development of pulmonary alveolar lipoproteinosis in rats.

[Interlaboratory quality control for the determination of blood lead. Initial experiences in Tuscany]

Results of an interlaboratory precision comparison programme of blood lead determination are presented. The samples consisted of bovine haemolyzed whole blood to which were added in pool small quantities of lead nitrate aqueous solutions to obtain two different concentrations of the metal (i.e. about 30 and 70 micrograms/dl). After each pool was well mixed it was divided into 15 ml portions in screw-top linear polyethylene vials and stored at -25 degrees C. The analytical methods used by the five public health laboratories participating in the programme were based on atomic absorption spectrophotometry. Three laboratories used methods which incorporate discrete sampling techniques (i.e. tantalum boat, electrothermal atomisation) and the remaining two, a method incorporating a sample preconcentration by solvent extraction and flame atomisation. During the six months period of the programme, fifty five results were obtained for each of the two pools of blood. Common statistical methods and the graphic system devised by Youden were used for data analysis. An acceptable agreement among results from the five laboratories has been obtained. The usefulness of this type of programme in improving analytical proficiency has been confirmed.