Bio-Inspired Method for Advanced Industrial Sludge Treatment with Closed Cycle Drying Process Filippo Rapisarda1, Riccardo Zammataro2, Giuseppe Di Lorenzo3 1 4R Ecologia & Costruzioni S.r.l., Chiaramonte Gulfi (RG), Italy 2 Department of Electric, Electronics and Computer Engineering, University of Catania, Catania, Italy 3 Euromecc S.r.l. S.S., Misterbianco (CT), Italy Abstract - The article describes a new bio-inspired process them into a single system. This means that the individual for the Advanced Treatment of Industrial Sludge with a Closed process deficiencies may be reset in a single cycle. In the Cycle Drying Process (TAFIPACC).This process represents an TAFIPACC process, the treatment of a certain type of waste, innovation in the way of treating sludge and other shovellable such as industrial sludge, will allow reducing its volume and residues deriving from machining and widespread industrial associated emissions, improving and minimizing the mobility processes in the largest industrial installations, such as refineries, of contaminated elements present in them. The high costs of steel mills, chemical plants, glass processing installations, numerous sludge treatment techniques currently in use have cosmetics manufacturing facilities, pharmaceutical triggered the development of alternative techniques such as the manufacturing plants, paper mills. The process starts from the one proposed. For the time being, it appears to be a more use of mixers in the production of concrete, and makes a thermal economical solution, which significantly reduces the mobility contribution to the material during mixing stage, thus separating of pollutants resulting in less environmental impact. part of these substances directing them to an integrated process of fractional distillation. The article introduces "clean-up" as a II. THE PROCESS new process through an innovative stage of evaporation and distillation in a closed cycle which is able to separate and collect TAFIPACC is a new automatic methodology for the pollutants and volatile components that would be otherwise treatment of polluted sludge that puts at the centre of the dispersed into the atmosphere as in the case of more traditional process 3 mc planetary mixers made of vibrated concrete [2] methods of open-cycle sludge drying. flanked by a series of devices that allow the extraction of the volatile portion of the worked refusal. Keywords - Industrial lime, treatment, pollution, energy Such a machine will be equipped, on the underside, with a recovery,environment, distillation device for heating, which has never before been applied to a concrete mixer. It allows a desired increase of the temperature I. INTRODUCTION of the content within the mixing tank, causing the evaporation Nowadays different industrial plant sludge treatment of volatile substances so that they separate from the sludge methods are in use. The main ones are: during treatment. - Centrifugation: it consists of separating water from sludge The functionality of this device implies the use of the by means of application of a centrifugal force[1]; heated air that will be made circulate in a cavity created around - Incineration: waste is eliminated by means of incineration, the mixing tank. The flow and temperatures will be regulated with the scope of obtaining energy. Only 70% of the volume of so as to control the thermal increments (critical factor under waste is eliminated with a subsequent ash disposal; study). - Inerting - Stabilization: the process of making highly Flanked to the mixer, an air recirculation circuit will be critical rejection for consistency and chemical-physical arranged. A high prevalence ventilator will suck up the air characteristics manipulatable and inhibiting the release of filled by vapour emitted from the mixing and heated sludge. contaminants. The set of the two mechanisms involves the The air is then pushed through the radiators of two heat transformation of waste into an easily movable solid, with little pumps. In its recirculation the air will pass from the first surface area exposed to the surrounding environment, inside radiator, where the less volatile part of the vapour will which the pollutants are trapped, stuck in insoluble condense to extract almost clean water. compounds; The air will then pass from the second, cooler radiator - Thermal Desorption: solid waste, such as soil and sludge, enabling condensation of the most volatile elements, i.e. is heated causing the vapourization of all those contaminants hydrocarbons at increased pollutant content to confer on the characterized by a boiling point inferior to the heating dedicated disposal. By doing this, it is avoided that these temperatures. The TAFIPACC method assembles by hazardous pollutants (e.g. harmful hydrocarbons, Benzene, integrating two types of processes closely related to each other: Fluorene, Pyrene, etc.), may be dispersed into the atmosphere, inerting - stabilization / thermal desorption and combining as is the case in many traditional systems for industrial sludge drying which inflict great damage for the environment. In these Copyright held by the author(s). first two radiators the initial hot air will cool; crossing the hot radiators of heat pumps it will regain temperature before 139 returning into the mixer, obtaining indeed an energy  The power plant where the epicyclic reduction recovery. Before entering the mixer, the fluid will pass through locates (Fig.2a); a rolling valve which will decrease the pressure inside the  The mixing tank with a 4 m diameter (Fig. 2b). mixer (facilitating the evaporation) and increase pressure in the branches of the closed cycle where radiators are located (thus facilitating condensation in cold radiators). A bag filter that saves impurities and dust entrance presides over the cleaning of this condensation line. The mixer will also be equipped with a moisture detection probe that, by sending data to the supervising automation device, will allow constant monitoring of the drying progress and automatically maintain the determined values of residual moisture. The machine will be sized to treat the quantity equal to 3 ton / h of polluted sludge and consequently produce 3 mc / h of high quality vibrated concrete, therefore it is suitable to be Fig. 2. (a) Power plant; (b) Mixing tank. applied (using appropriate equipment available on the market) for the packaging of different kinds of high quality goods (e.g. The electric motor, placed above the reducer cap, through tiles, building blocks, interlocking paving, heavy blocks for an epicyclic water seal reducer and gears transmission, various uses, etc.). This places an added value to the sludge transfers the movement to the mixing equipment. treatment process with a profitable use of the output material. Every motor is connected to its own reducer which presents To treat 3 tons of sludge, around 4.7 tons of clean inert and 0.6 sprocket wheel which in turn gets started with the fifth wheel, tons of cement will be used. namely a type of axial bearing for low rotational speed and These are the initial reference values that will be tested and high axle load applications. The fifth wheel is composed of an optimized during the research. By treating 3 tons of sludge it is internal ring, fixed to the power loom, and the external slip ring supposed that 30% of the liquid part from the sludge will be supporting the whole disk. extracted by the circulation of air in the distillers. Of this liquid To the plate carrier, bottomed scraping shovels, of side, and part, the desired goal is to obtain 50% clean and immediately mixing stars are fixed. usable water and the other 50% of water assigned to an The latter are joint to the fifth wheel so to be consequently integrated module in the prototype dedicated to the treatment of dragged with the rotation of the second, which rotating around liquids with high content of pollution, whereas the residual its own reference axis gears with the fixed crown. water will be recovered by separating any contaminants present The inferior part of the mixer consists of a mixing tank with in it. an opening at the bottom closed by a rotating hatch whose The TAFIPACC method, as the result of the combination automate opening occurs by means of a hydraulic cylinder of two types of sludge treatment (inerting - stabilization / once the mixing stage of concrete has finished. thermal desorption) into a single system, permits a significant This is hinged in its axis which rotates inside the sleeve. reduction of costs. Moreover, this proposed alternative For this reason, the axis and its relative bearings must be technique is not only more economically advantageous but also suitably measured. minimizes the mobility of pollutants resulting in a lower In order to get the tank sizing, some calculations based on environmental impact. ''soft output volume'' which indicates the finished product which derives from the conclusion of the manufacturing cycle and ''vibrating output volume'' which is the volume of the sleeve once it is implemented and thus vibrated, have been made. Once the broad measures of the tank, and hence of the hatch, were stated, the measures of the hydraulic piston and supports, the fixed one (tank side) and the mobile one (hatch side), were determined assuring the correct alignment among these, thus avoiding transverse forces components which cause an early wear of the scroll bushing of the shank [3, 4]. By considering the exercise pressure as equal to 180 bar, the tangential force was calculated per unit lengh, which acts on the outer edge of the hatch through the balance of the moments with regard to the pole consisting of the axis of the hatch (Fig. 3). Fig. 1. Process diagram. III. PLANETARY MIXER The structure of the mixer consists of two parts: 140 An increase in the water-cement ratio over 0.4 leads to a degradation of the final characteristics of strength and permeability of concrete as shown in the charts below: Fig. 3. Forces acting on the hatch. Fig. 4. Strength and permeability of concrete. For a watertightness of the tank, seals in polieuretano lodging on the contact surfaces of the tank and hatch are arranged. These, going through with a creeping contact, are During the testing phase of TAFIPACC processes subject to wear, hence the necessity of evaluating the tension proposals to optimize the product output, both in terms of degree (4) necessary to ensure tightness, avoiding excesses physical characteristics and costs, will be defined. which cause an early wear of seals. In the solution of the matter, in addition to material, profile shape and the interference degree (5) between the fixed part (the tank) and V. DETAILS OF THE PROCESS the moving part (the hatch) of the seals couple play a leading To test the TAFIPACC treatment, the evaluation, by means role. of an appropriate analysis of the chemical - physical The door is supported by the shaft sized to withstand the characteristics of any potential sludge to be treated, has been stresses due to the weight of the concrete and the forces performed. The analysis allows both to choose the most induced by the opening cylinder. suitable sludge in terms of the content of pollutants, with which The shaft has a variable diameter along the axis due to the to run tests, and to compare the chemical characteristics of the shoulders for the bearings, for which the correct coupling pre- and post-treatment sludge. tolerance has been obtained [7]. Tests have been carried out on the sludge falling within the category "CER 19:08:13, sludges containing dangerous IV. THE PACKAGING OF THE CONCRETE substances coming from other treatments", i.e. sludge from industrial wastewater (hazardous). One of the techniques currently employed for inerting The current methods for treating dangerous sludge are dangerous sludge is packaging in concrete containers for illustrated below; and a possible scenario of application of the recycling as an aggregate [8]. method and its potential TAFIPACC benefit is simulated. The In this way the pollutants present in the sludge are selected waste can actually be decomposed into its two main incorporated in the cement matrix at high strength avoiding the constituents: reaction with the atmospheric agents and enter the Residue or dried substance at 105°C% P 42.61 environmental life cycle. Depending on sludge composition, hydrated lime which Water %P 57.39 acts as a disinfectant and contrasts the odoriferous waste The sludge then presents traces of hydrocarbons and heavy components can be used. metals. So 1000 kg of water results in about 570 kg of sludge. Since the proposed waste treatment process presupposes the In the inerting process by means of concrete packaging, the use of concrete packaging, a reference to the guidelines for its water in the waste is used as the water to hydrate the cement. production must be made. In order to obtain common medium The following ratios, which are necessary to obtain good strength and consistency, a cubic meter of concrete is concrete, must have fixed values: composed of: - The water/cement ratio is kept low in order to ensure the - Sand 720 kg production of a concrete structure of high mechanical quality, - Crushed 1280 kg as it is crucial that the pollutants are blocked in the cement - Cement 300 kg matrix. - Water 120l kg - the ratio of the inert part with the cement that by a ratio of the part of the hydraulic binder used and the solid inert part The relationship between water and cement a / c = w is of a from the sludge and by the granulometric Joint employed, must great importance. be around 4 (+ Inert dry part of the sludge) = 3.85 (Cement) For a perfect reaction of cement, a ratio w equal to 0.28 [9] - the ratio of lime and the solid matrix of the compound. which would be the reaction stoichiometric ratio would suffice. Lime is used to disinfect and eliminate the odorous part of the In reality, this ratio is slightly increased to allow a better waste. However, lime stabilization may allow odors to return; hydration of cement and provide the mixture with certain To eliminate this problem and reduce pathogen levels, addition workability. of sufficient quantities of lime to raise and maintain the biosolids pH [10] Its effectiveness is proportionate to the 141 quantity of lime used, relative to the entire solid matrix of the Clean Inert 3665.5 2.6 1409.82 1333.47 compound consisting of the solid part of the sludge, aggregates Lime 709.13 2.4 295.470 257.971 and concrete, resulting in a good value of about Concrete 6284.7 2748.87 2286.27 0.17 (Lime) = 0.17 (+ Inert part dry sludge + cem.). Below is a comparison between two treatment methods. When the present amount of dry sludge and water is The delta value between the weights suggested by the two known, the amount of cement, lime and clean inert is obtained. formulas is highlighted. Therefore the components needed to prepare concrete with TABLE III. COMPARISON BETWEEN TWO TREATMENT METHODS. a ton of sludge are summarized below, stating the required weight and volume. Component Initial Formula After DELTA Description Formula [kg] Treatment [kg] [kg] TABLE I. COMPONENTS REQUIRED FOR A SLUDGE TON. Sludge’s Dried Part 426 426 0 Water (In the dried 574 424 -150 Specific Weight Sludge) Component Weight Volume Weight [kg/mc of Cement 1435 1060 -375 Description [kg] [lt] [t/mc] concrete] Clean Inert 5113 3666 -1447 Sludge’s Dried Part 426 1.6 266.25 112.546 Lime 1200 709 -491 Water (In the Sludge) 574 1 574 151.646 Calcestruzzo 8748 6285 -2463 Cement 1435 3 478.33 379.116 Clean Inert 5113 2.6 1966.54 1350.82 Lime 1200 2.4 500 317.031 It can be stated that by using TAFIPACC treatment Concrete 8748 3785.12 2311.15 method, the following savings of valuable materials can be made, in terms of weight and price: The numbers represent those which are necessary to pack TABLE IV. SAVING OF MATERIAL. concrete using the input of a ton of sludge according to the relations above. By converting the weight into volume, through Component [kg] [Euro/Ton] [Euro] the specific weight, it appears that in order to carry out the Cement 375 70 26.25 packaging of a ton of sludge a mixing tank of 3.78 mc is necessary (in red in the table). The relationship introduced Clean Inert 1447 5 7.2 above will be taken into account also in the preparation of a Lime 491 107 52.6 new formula to be used downstream of a preliminary Total 86 dewatering of the sludge through the treatment using the new To treat then the same amount of sludge of 1000kg, a net TAFIPACC plant. The only ratio that will be altered is the one saving of 86 euros in terms of savings of valuable material between lime and the solid matrix of the compound. It will be (aggregates, cement and lime) is obtained. reduced, without altering the quality of mps in output, since during the evaporation process inside the TAFIPACC VI. PROCESS ENERGY BALANCE treatment plant the particles containing the volatile odoriferous substances will also be removed. Relative humidity RH (%) Drastically decreasing the presence of such substances The amount of water vapour that can be contained in one within the compound, it is also possible to reduce the amount kg of dry air is not unlimited. Over a certain amount, the added of lime required to eliminate odours. It is prudently estimated steam condenses in the form of minute droplets (i.e. fog effect). that the intake of lime can be reduced by up to 20%, bringing Relative humidity is the percentage of vapour contained in the ratio of 0.17 down to 0.137. the air in relation to the maximum quantity holding in it at a If we aim to eliminate 15% by weight of the sludge in the certain temperature. analysis, it can be done by extracting 1000kg from the initial For example: 1kg of air at a dry bulb temperature of 20 ° C sludge and about 150lt of water incorporated therein prior to may at most contain 14.7g of water vapour (added steam the production of concrete. Considering the same sludge should condense); therefore, the mixture consisting of 1kg of without 150 kg of eliminated water, and keeping the dry air and 14.7g of water vapour has, at a temperature of 20 ° relationships stable and unvaried, less than that from lime (0.17 C, the relative humidity equal to 100% (saturation conditions); to 0.137), the new formula will be as follows, highlighting the however, at the same temperature, if 1kg of dry air contained required values in green: 7.35g of steam (i.e. half of the maximum amount of steam miscible at 20°C), the mixture would be at a the relative humidity of 50%. The relative air humidity is strictly related to the dry bulb TABLE II. NEW FORMULA FOR A SLUDGE TON. temperature. At parity of grams of water vapour present in a kg of dry Specific Weight air, the relative humidity increases as the temperature Component Weight Volume Weight [kg/mc of decreases; this can be explained as follows: the lower the air Description [kg] [lt] [t/mc] concrete] temperature, the lower the miscibility of the water vapour in 1.6 the air [11]. Sludge’s Dried Part 426 266.25 154.973 Water (In the dried The psychometric chart at a given pressure (the one 1 reported herein at a pressure of 1,013 bar) represents curves of Sludge) 424 424 154.245 Cement 1060 3 353.33 385.613 various UR percentages. In particular, the upper one is the 142 curve of 100% RH that represents the dew point of water the second phase the dissipated vapours are captured by the vapour mixed in function of temperature and also indicates the condensing coils. amount of water vapour miscible in 1 kg of air. Considering the process in more detail, its phases are indicated as follows: 1) Heating of the sludge and the interior of the mixer up to 40 °C. 2) Evaporation of the liquid part from the sludge in vapour state. 3) Air Circulation charge of steam inside the condensation circuit. 4) Decresing the ambient temperature (vapour charge) from 40 °C to 5 °C. 5) Condensation of water For energy purposes, in steps 1) and 2) the energy to raise the temperature and to enable further evaporation must be produced. In point 3) energy is released to make the air circulate. In steps 4) and 5) the same energy must be subtracted Fig. 5. Psychrometric chart from the current of air to decrease the temperature again and By varying the conditions of the fluid, the water vapour cause the vapours to condense. contained therein can then condense so that it is possible to pull To estimate the energy needed to carry out this cycle, the it out in the liquid form. Observing a simplified diagram, it can Specific Heat (CS) of the compounds involved must be taken be concluded that having a mass of air at 40 ° C at the relative into account: humidity equal to 100%, the total amount of water contained in it results in almost 50 g / kg of air. Considering with a good CS H2O(Liquid) = 4.180 [J/(kg °C)] approximation that 1 kg of air corresponds to 1mc of air under CS H2O(Steam) = 1.940 [J/(kg °C)] normal conditions, it can be stated that about 50 g / m3 of air CS Sludge (Dry part) = 1.000 [J/(kg °C)] are inside. CS Humid Air = 1.030 [J/(kg °C)] Specific heat indicates the energy required for the temperature of a kg of compound to vary a degree. Latent heat of vaporization (lv) indicates the energy required to make the liquid evaporate. lv H2O = 2.272 [J/g] For purposes of energy calculation, it is assumed that for simplicity only water evaporates and then condenses, for the following reasons: 1) water is by far the largest part of the volatile components in sludge composition; 2) the latent heat of evaporation and condensation of water is among the highest. It is equivalent to 2272 (J / g), so, evaporation of 1 gram of water requires 2272 joules of energy (0.6311 watt-hours). Likewise, this energy must be subtracted Fig. 6. Curves of the Various UR Percentages from 1 gram of water vapour to condense it. The energy needs are further examined point by point. If the air is cooled to 5 ° C, the water content miscible in it 1) Increase in temperature from 15 ° C (average in the form of vapour passes from almost 50 g / kg to about 5 g temperature between summer and winter is considered) at 40 ° / kg. As a result, 45 grams of water condense. of 1000 kg of sludge consisting of 426kg of dry part and 574 Energy balance kg of water. DT = 25 C In order to estimate the energy contribution, the cycle 426 [kg] * 1.000 [J/(kg °C)] * 25 [°C] = 10.650 kJ  2.95 envisaged by TAFIPACC method is briefly summarized. The kWh method consists of a dehydration process of the sludge prior to 574 [kg] * 4.180 [J/(kg °C)] * 25 [°C] = 59.982kJ  16.6 kWh the concrete packaging. Considering the same 1000kg of To heat the sludge from 15 to 40 °, 19:55 kWh are then sludge and an elimination of water content equal to 15% by needed. sludge weight, the system must expel 150lt of water. This 2) Evaporation of 150kg (150.000g) of water to subtract process of water extraction from the sludge is completed in two from the sludge, in order to get: 150,000 [g] * 2.272 [J / kg] = distinct phases that require a certain energy intake. 340,800 kJ  94.6 kWh In the first phase, it is necessary to evaporate water and the This energy will be administered to the sludge in two volatile polluting substances in the sludge to separate them forms: from the sludgy mass and dissipate them in the air; whereas in  70 kWh heating resistors on the tank bottom  45 kWh Mixing (Friction) 143 The first cited energy will be delivered to the sludge in For simplicity of calculation the duration of the drying drying by the resistances that are mounted under the tank process equivalent to 1 hour is assumed, where the fan bottom. The second contribution will be provided by the consumes 10kWh. mixing engine. The mixer will have installed engine power The following approximations are calculated by excess: equal to 135kW. This engine power will be fully exploited when the mixer 1) Heating Sludge 20kW works at full speed and full load. In the first phase of drying the 2) Evaporation 95KWh mixer will contain only 1000kg of sludge which must be 3) Air-handling 10kWh dehydrated. In this phase the mixing engines will exploit only a 4) Steam cooling 5kWh portion of the energy consumable by them which can be 5) Condensation 95KWh estimated at 30% of the nominal value corresponding to 45 Total 225KWh kW. This power is used to stir the sludge in drying, and then the This allows calculating the required energy and power, so, friction of the material ultimately converts into thermal energy in order to extract 150lt of water from the sludge, for the and therefore heat. Clearly, this power will be required for the treatment of 1000kg of sludge, 225kWh are necessary. longest duration of only one drying step. It is emphasized that the above calculations have been After completing the dehydration, the mixer will be loaded carried out without considering the recovery of heat that could with the other components to produce 2.8mc of concrete and be implemented in the radiators, and are therefore certainly employ 135kW for mixing a couple of minutes. This amount of estimated above. energy is not considered because in any case there would be no Economic analysis matter TAFIPACC treatment. Considering the price of electricity of 0.16 euros / kWh, the 3) To calculate the air inside the tank mixing with water total costs will be 0.16 € / kWh x225 kWh = € 36 for the from the sludge one can refer to the following psychometric treatment of 1 ton of dangerous sludge. chart (Fig. 3). Drawing up a balance between the precious raw material The content of water miscible with the air at a temperature savings (as seen in the previous paragraph, and amounted to € of 40 ° C is almost 50 grams. Handing in the condensing coils 86) and the expenditure of additional energy, by using the will bring the temperature to 5 °. At this temperature, proposed TAPIFACC treatment plant, the net cost savings for maintaining a relative humidity equal to 100%, the water the dangerous sludge treatment of 1000kg will be: vapour contained in the miscible kg of processed air passes from 50 to 5 grams. The water vapour-laden air after passing COST SAVINGS = 86-36 = 50 Euro / Ton of Sludge through the condenser coil will have then downloaded 45 grams of water. Below is shown the comparison of two different recipes A kg of air corresponds to approximately 1mc of air under usable with traditional system and system with TAFIPACC normal conditions. We know that for every cubic meter of air, dehydration. 45 grams of water can be extracted; so, in order to extract 150lt Furthermore, other important economic considerations can of water (150,000 grams) at least: 150,000 / 45 = 3333 cubic be discussed. meters of air will have to be processed. The table below compares two different treatment methods, 4) Taking the count on the basis of an hour and putting i.e. the traditional system and TAFIPACC dehydration in terms some mc flow to make up for any losses, it will be necessary to of the composition of 1 cubic meter of concrete as a product of recirculate a fan at 4000mc / h flow rate. For a prevalence of the two different methods: approximately 400mm of water column, an aspirator of this kind will require a power of about 10kW. TABLE V. COMPOSITIONS OF 1 CUBIC METER OF CONCRETE Reduction of temperature from 40 °C to 5 °C 150 kg of water vapour in the air: TRADITIONAL TAFIPACC Weight Weight DT = 35 °C Component Description [kg/mc of Conc.] [kg/mc of Conc.] Sludge’s Dried Part 112.55 154.973 150 [kg] * 1.940 [J/(kg °C)] * 35 [°C] = 10.185 kJ  2.82 Water (In the sludge) 151.65 154.245 kWh Cement 379.12 385.613 Clean inert 1350.82 1333.47 To cool the water vapor from 40 °C to 15 °C, 2.82 kWh are Lime 317.03 257.971 Concrete 2311.15 2286.27 needed. 1) Condensation of 150kg (150.000g) of water to be subtracted from the sludge, so to get: Using TAPIFACC method, a cubic meter of concrete is 150.000 [g] * 2.272 [J/kg] = 340.800 kJ  94.6 kWh produced with a greater amount of dry sludge (154 kg vs. 112 kg) and fewer raw materials (lime, 257 kg vs. 317 kg). Once diffused water in the form of steam flows through the From the economic viewpoint, the cost of waste condenser batteries, 150lt of water are needed to condense contribution to the reception facilities would amount to 174 again by using additional 92 kWh. The latent heat of Euros per ton (see Annex to this report via email and the condensation is in fact similar to that of evaporation. "anac" tender awarded € 1,081,700 to treat 5 800 tons of The condensing coils will have an installed capacity of sludge). 95kW to condense the amount of 150 kg water vapour. Considered that the transport incidence is 12.5 € / t, the treatment costs per ton of sludge results in 1 081 700/5800 = 186.5 € / t; minus the shipping costs 1865.5-12.5 = 174 € / t, so 144 the price for the treatment of 1 ton of sludge is 174 € / t). Besides the economic advantage outlined above, there are Considering the costs of valuable materials outlined in the table other benefits which are difficult to quantify economically: above, and learning that the selling price of 1 cubic meter • 30% less production of blocks (2.7 compared to 3.7 cubic concrete is 35 €, the treatment of 1 ton of sludge amounts to: metres per 1 ton of sludge): With TRADITIONAL method: • Less handling within the plant; • Less area for storage; TABLE VI. TOTAL COST TO TREAT A TON OF SLUDGE WITH • More ease of sale (it must sell less); TRADITIONAL METHOD • Minor volume needed to mix 1 ton of sludge (3.78 to 2.7 Weight Total cubic meters); Component Weigt Volume [kg/mc of Cost Cost • Smaller mixing bath (only 3mc,. mixers 2 mc, where 2 Description [kg] [lt] [Euro/ton] conc.] [Euro] cycles are needed to treat 1 ton of sludge, and a mixer of 4 mc Sludge’s Dried does not exist on the market) Part 426 266.25 112.546 -174 -174 • Fewer raw materials employed, less amount of storage Water (In the needed; sludge) 574 574 151.646 -174 • Greater ability to increase the amount sludge to be treated. Cement 1435 478.33 379.116 70 100.45 Clean Inert 5113 1966.53 1350.82 5 25.565 Considering the amount of sludge transferred in the last two Lime 1200 500 317.031 107 128.4 years to the 4R, which is approximately 10 000 t, and Concrete 8748 3785 2311 80.415 supposing that it had been treated by using the TAFIPACC method, it would have resulted in a profit of 14.6 € / t x 10 000 - Production: 3.78 cubic meters of concrete per ton of t = 146 000 € over the last two years. treated sludge In recent years the 4R has limited the amount of sludge to - Revenue from sale = 35 x 3.78 = 132.3 € be treated but in the coming years, thanks to the convenience of - Cost of raw material production (considering the negative the TAFIPACC system, it will be able to treat about 30,000 supply of sludge) = 80.40 € per ton of treated sludge. tons of sludge. With the method TAFIPACC: With this amount of sludge the annual revenue would -Production: 2.75 cubic meters of concrete per ton of amount to around € 440 000. treated sludge Assuming the sale price at 4R (see paragraph 11 of this - Revenue from sale = 35 x 2.75 = 97.3 € report) amounting to 80,000 €, the required amount of sludge - Cost of raw material production (considering negative to be treated in order to pay back the cost of the plant is about sludge supply) = 5.60 € per ton of treated sludge (i.e. spending 5,600 t of sludge. Considering the current data on 4R sludge less on raw materials than paying for the transfer of sludge) processing amounts one year will be enough. - Energy costs (more than the traditional process) = 36 € VII. SCALED PROTOTYPE TESTING per ton of treated sludge (see previous paragraphs). Before launching the design, modeling and implementation TABLE VII. TOTAL COST TO TREAT A TON OF SLUDGE WITH of the TAFIPACC project prototype, a small prototype on a TAFIPACC METHOD reduced scale was developed, in order to test the equipment and conduct tests on small amounts of sludge to find the right Weight Total Component Weigt Volume [kg/mc of Cost Cost components to add in the mixing stage for waste recovery. Description [kg] [lt] [Euro/ton] Analyzing dozens of samples obtained during the tests with the conc.] [Euro] Sludge’s Dried scaled prototype of the TAFIPACC system, it was possible to Part 426 2665 154 -174 identify a modus operandi that would permit optimization of -174 Water (In the the process in terms of energy and time. sludge) 424 424 154 -174 Cement 1060 353 385 70 74.2 Clean Inert 3665 1409 1333 5 18.32 Lime 709. 295 257 107 75.87 Concrete 6285 2748 2286 -5.59 Therefore making an economic comparison between the two treatments for 1 ton of sludge, the following conclusions can be drawn: TABLE VIII. MARGIN INCREASE WITH THE TAFIPACC PROCESS TRADITIONAL TAFIPACC Cost of raw material [Euro] -80 5.6 Sale revenue [Euro] 132.3 97.3 Margin [Euro] 52.3 66.9 Margin increase for a tone of Sludge 14.6 € (66.9-52.3) Fig. 7. Scaled prototype. Employing the TAFIPACC method, an additional gain of 14.6 € per ton of treated sludge equals about 30% margin more After hundreds of tests with scale prototype the following than the current (14.6 / 52.3) is derived. conclusions can be drawn: 145 - The reducing process of the sludge weight improves if [6] Calì, M., Oliveri, S. M., Ambu, G., & Fichera, G. (2018). An integrated inert is also included in the process of mixing; approach to characterize the dynamic behaviour of a mechanical chain tensioner by functional tolerancing. Strojniski Vestnik/Journal of - The times of the sludge weight reduction decrease Mechanical Engineering, 64 (pp. 245-257). substantially with the addition of insulation in the tank mixing; [7] Ambu, R. (2013). A method with a statistical approach for the - The times of the sludge weight reduction diminish evaluation of tolerance chains. In Advanced Materials Research 651, significantly with the increase of the temperature at which the (pp. 601-606). Trans Tech Publications. mixing process and then the heating of the mixing tank take [8] Frigione, M. (2010). Recycling of PET bottles as fine aggregate in place. concrete. Waste management, 30( 6), (pp. 1101-1106). [9] ACI Committee, American Concrete Institute, & International CONCLUSIONS Organization for Standardization. (2008). Building code requirements for structural concrete (ACI 318-08) and commentary. American In comparison to the currently available industrial sludge Concrete Institute. treatment methods, the proposed method intends to [10] Williford, C., Chen, W. Y., Shamas, N. K., & Wang, L. K. (2007). Lime significantly reduce the mobility of contaminants contained in stabilization. In Biosolids Treatment Processes (pp. 207-241). Humana the sludge. The developed method allows extracting the Press. volatile portion of the sludge by means of a heating device [11] Yadav, Y. K., & Kaushik, S. C. (1991). Psychometric technoeconomic assessment and parametric studies of vapor-compression and solid/liquid applied for the first time to a concrete mixer of great desiccant hybrid solar space conditioning systems. Heat Recovery dimensions and thus resulting in lower environmental impact. Systems and CHP, 11(6), (pp. 563-572). This promotes a desired increase of temperature so as to trigger [12] Kapuściński, T., Nowicki, R.K. and Napoli, C., 2017, June. Comparison evaporation of volatile substances and enable their separation of Effectiveness of Multi-objective Genetic Algorithms in Optimization from sludge. The mixer, flanked by an air recirculation circuit, of Invertible S-Boxes. In International Conference on Artificial Intelligence and Soft Computing (pp. 466-476). Springer. is also equipped with a moisture detection probe. An added [13] Woźniak, M., Połap, D., Napoli, C. and Tramontana, E., 2017. value of a sludge treatment process is determined with the Application of bio-inspired methods in distributed gaming systems. profitable reuse of the output material. To treat 3 tons of Information Technology And Control, 46(1), pp.150-164. sludge, 4.7 tons of clean inert and 0.6 tons of cement were [14] Bonanno, F., Capizzi, G., Sciuto, G.L. and Napoli, C., 2015, June. used. During the TAFIPACC process testing, the best solution Wavelet recurrent neural network with semi-parametric input data preprocessing for micro-wind power forecasting in integrated generation to optimize the output was defined, both in terms of physical Systems. In International Conference on Clean Electrical Power characteristics and costs incurred. In particular, tests and (ICCEP), (pp. 602-609). IEEE. optimizations were performed using hazardous sludge "CER [15] Capizzi, G., Sciuto, G.L., Monforte, P. and Napoli, C., 2015. Cascade 19:08:13 sludges containing dangerous substances from other feed forward neural network-based model for air pollutants evaluation of treatments", i.e. sludge from industrial wastewater (hazardous). single monitoring stations in urban areas. International Journal of Electronics and Telecommunications, 61(4), pp.327-332. By using the TAFIPACC method, in which the amount of [16] Zanetti, E. M., Aldieri, A., Terzini, M., Calì, M., Franceschini, G., & dangerous substances inside the compound is dramatically Bignardi, C. (2017). Additively manufactured custom load-bearing decreased, it is also possible to reduce the amount of lime implantable devices: grounds for caution. Australasian Medical Journal, required to eliminate odors. It was estimated that it is possible 10(8), p. 694. to reduce the amount of lime by up to 20%, bringing the ratio of 0.17 down to 0.137. The research was concerned with the development of virtual models and relative analytic calculations, as well as the performance of experimental measurements in the field in order to optimize every single component to come up with innovative design. In particular, the research involved static and dynamic simulations, structural dimensioning and prototype creation of the main components of the plant using 3D printing technology on 1:10 scale. REFERENCES [1] Gupta, V. K., Ali, I., Saleh, T. A., Nayak, A., & Agarwal, S. (2012). Chemical treatment technologies for waste-water recycling—an overview. Rsc Advances, 2(16), (pp. 6380-6388). [2] Deligiannis, V, & Manesis, S. (2008). Concrete batching and mixing plants: A new modeling and control approach based on global automata. Automation in Construction, 17(4), 368-376. [3] Ambu, R., Bertetto, A. M., & Mazza, L. (2016). Re-design of a guide bearing for pneumatic actuators and life tests comparison. Tribology International,96,(pp. 317-325). [4] Gamez-Montero, P. J., Salazar, E., Castilla, R., Freire, J., Khamashta, M., & Codina, E. (2009). Misalignment effects on the load capacity of a hydraulic cylinder. International Journal of Mechanical Sciences, 51(2), 105-113. [5] Calì, M., Oliveri, S. M., Sequenzia, R., & Fatuzzo, G. (2017). An effective model for the sliding contact forces in a multibody environment. In Advances on Mechanics, Design Engineering and Manufacturin (pp. 675-685). 146