wastewater sludge management: a brazilian approach · wastewater treatment and sludge production in...

Wastewater Sludge Management: A Brazilian Approach

C.V. Andreoli*, L.H.P. Garbossa**, G. Lupatini** and E.S. Pegorini**

* UNIFAE Centro Universitário - Rua 24 de Maio, 135 – Centro, CEP: 80230-080 - Curitiba – PR – Brazil.(E-mail: [email protected])

**Companhia de Saneamento do Paraná – Sanepar, Rua Engenheiro Rebouças, 1376 – Rebouças,CEP: 80215-900 – Curitiba – PR – Brazil(E-mail: [email protected]; [email protected], [email protected])

Abstract: In this article it is presented the main trends for the wastewater sludge management in Brazil. To achievethis, some information about the sludge management was raised, such as sludge quantitative and qualitativecharacteristics, legislation and legal references and background, also some information about sludge managementin some Brazilian states. Based on this information, the main obstacles to its utilization in this area are outlined. Thesludge management cannot be understood for sanitation managers as a way to rid of a problem, but in contrast, away to maximize the benefits through the use of it, carefully considering the environment and sanitary risks, to generatesafe and economical viable alternatives that will guarantee the sustainability of the process.

Keywords: Brazil; disposal; land use; management; wastewater sludge.

INTRODUCTIONThe Brazilian sanitation sector, as in many countries of the world, is facing a number of difficulties to managethe residues generated by the water and wastewater treatment plants. Over the last few years, severalinvestments in this sector have been made in order to meet the growing pressure made by both society andenvironmental agencies seeking the protection of the environment, quality of life, and social welfare.

As a result of the democratization and implementation of collection systems and treatment processes, a growingvolume of complex residues is formed. For this reason, a new management and final disposal problems iscreated. Among these residues of the sanitation sector, the sludge found in wastewater treatment plants (WWTP)represents one of the most critical residues due to the great volume that is produced and the high managementcosts (processing and final disposal). It is a process of great complexity because it demands solutions that,generally, go beyond WWTP?s reach. Nevertheless, most of the times, these actions are essential in order to fullyaccomplish the sanitary, environmental, and social results expected from the sanitation company.

In Brazil, these activities have been lately neglected, accumulating great environmental liability susceptibleto lawsuit and fines by environmental agencies. Observing the series of omissions, it starts at the conceptionof the treatment systems, which ignores the residues management, going through the environmental licenseagencies during the implementation of new companies and it finally ends up being administrated as anemergency, without adequate planning, causing great environmental impacts and operational costs. (Pegoriniand Andreoli, 2006).

In this scenery, this article intends to present the main trends for the wastewater sludge management inBrazil. To achieve this, some information about the sludge management was raised, such as sludge’squantitative and qualitative characteristics, legislation and legal references/background, and also someinformation about sludge management in some Brazilian states. Based on this information, the main obstaclesto its utilization in this area are outlined, as well.

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WASTEWATER TREATMENT AND SLUDGE PRODUCTION IN BRAZILBased on the information from IBGE – Brazilian Institute of Geographic Statistics, the total populationestimated in 2005 for the 5,564 municipalities corresponded to 184.1 million inhabitants. Considering thisfigure, approximately 150.1 million inhabitants (81.5%) lived in urban areas, while 34 million (18.5%) livedin rural areas.

According to the SNIS – National Sanitation Information System last publication, in 2005, there was a total ofover 134 million inhabitants, 89.3% of the urban Brazilian population. In this research, it was found that thesanitation services supply reaches: 96.3% of this population with domestic water supply, 47.9% withwastewater (sewage) collection, and 31.7% with wastewater treatment.

Based on the numbers presented by SNIS, it is possible to estimate that 64.18 million inhabitants have awastewater collection system and 42.47 million inhabitants have wastewater treatment systems. In otherwords, 66% of the collected wastewater is treated.

SNIS (2006) report also states that, in 2005, 658 million cubic meters of wastewater were disposed into thewater bodies without any proper treatment approximately.

It is important to emphasize that, in most cases, the people that do not have their wastewater collected,manage their own sewage individually, by using unitary systems (septic tanks), what represented, in 2005, 78million inhabitants.

Measured and/or estimated sludge productionThere are only a few studies about the sludge production in Brazil nowadays. Machado (2001) carried out asurvey about the sludge production in the Brazilian territory between 2000 and 2001. In his work, 275 waterand wastewater treatment plants were analyzed from a total of 984. Tables 1 and 2 feature the estimation ofwastewater sludge production by region and the final disposal, respectively.

Table 1: Sludge production by region (2000-2001)

Source: Machado, 2001. * humid sludge.

Table 2: Final disposal of the produced sludge.

Source: Machado, 2001. * humid sludge.

Considering the population that has access to the WWTP services (approximately 12,777,974 inhabitants) andthe value of 33 gTSS.year-1, Machado (2001) has estimated a sludge production of 151,724 ton TSS.year-1 fora total of 275 WWTP.

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According to an essay developed by SNIS in 2005, about 46,836,317 inhabitants have a wastewater collectionsystem (Table 3). Taking into account that the rate among collection and treatment of wastewater is about 66%and the estimated sludge production per capita is about 33 g TSS.year-1 (Machado, 2001), it is possible toestimate a production of 372,000 ton TSS.year-1.

Table 3: Wastewater collected and treated volumes in Brazil for the year 2005.

Source: SNIS (2006)

According to the Sabesp (Sanitation Company of the State of São Paulo), the eight main WWTPs in the stateof São Paulo put together have a production of 528 ton.day-1 (humid sludge), which accounts for about 48,000ton.year-1.

In the State of Paraná, sludge production has doubled between 1999 and 2003, from 2,000 m3.month-1 to 4,000m3.month-1. For 2007, assuming that the WWTP has been working with the project flow, it a sludge productionof 10,000 m3.month-1 is estimated, which is discarded entirely from the systems

SLUDGE QUALITYPhysical-chemical and sanitary sludge CharacteristicsCurrently, there are very few wastewater treatment systems that have information about the sludge compositionproduced in their facilities. The survey developed by Machado (2001), for example, pointed to a greatuncertainty about the Brazilian average, as shown in Table 4. It is important to outline that the wastewatertreatment companies located in the South, Southeast and Federal District were the ones that have contributedthe most with information.

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Table 4. Mean wastewater sludge composition in Brazil (2000-2001) and Paraná state (2006).

Generally the brazilian WWTPs do not have heavy metal contamination in their sludges. The contamination ofsludge was detected just in some isolated cases. Those metal contamination are related to irregularcontributions from industrial areas.

PROCEDURES AND LEGAL REQUIREMENTS FOR SLUDGE UTILIZATION AND FINAL DISPOSAL FOR SOME STATESIN BRAZILRecently, the Brazilian Federal legislation has changed the criteria and procedures that define the use ofwastewater sludge in agricultural areas, with the purpose or bringing benefits to the plantation areas andavoiding the risks for human health and the environment. This new rules are in the 375 resolution from August29th, 2006 and were established by the National Council of the Environment (Conama). They defined sevenprocesses for reduction in the vectors attraction, among these processes are anaerobic digestion, aerobicdigestion, composting, chemical stabilization, drying and soil incorporation. This resolution also presentsanother eleven processes for pathogenic agents reduction, with six processes to convert wastewater sludge toclass A sludge and five processes to convert it to class B. Also, this resolution establishes 18 month timeperiod for the adaptation of the Brazilian states to the new regulations.

The state of Paraná was the first one to publish its new legislation adapted to the federal laws. TheEnvironment and Water Resources Agency of the State of Paraná (SEMA) published the 001/07 – SEMA, whichhas the rules that specify the procedures for the use of sludge obtained from wastewater.

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The new edition of the legislation established new reference values for heavy metals, as presented in Table5. The other states that have their own legislation even though they are not adapted to the new reality yet.

Table 5. Heavy metals limits according to the legislation

As it can be observed in Table 5, the sludge parameters for the Brazilian states are more permissible than thenew federal legislation, so that these states will have to adequate themselves within the next 18 months.

The limits in the new federal law and the actual state laws are presented en Table 6 concerning the pathogenicmicroorganisms presence and limits.

Table 6: Pathogenic microorganisms limits in Brazil and its states.

NATIONWIDE WASTEWATER SLUDGE KNOWLEDGE PRODUCTIONThe Brazilian Sanitation Research Program (Prosab) is a public research program that has received financialsupport from Finep, a public company that finances the Projects and Studies, since 1996.

Prosab program was created with the purpose of developing and optimizing technologies in the water supply,wastewater treatment, and solid residues management. Furtado et al., (2005) presents the basics of theProsab program: 1 – Review of the present technological standards , with the objective of allowing theamplification of the sanitation services, by the establishment of adequate rules that recognize each local andregional singularities and the different levels of meeting the population needs, preserving and reestablishingthe environment; 2 – The pursuit of technology distribution for the public domain 3 – Support participativeprocesses, creating cooperative networks of research to discuss subjects, previously defined. During itsevaluation, Prosab received answers from the coordinators of 33 projects out of ma71 that were developed inthe three first research edictals(1996,1998,2001 respectively).

These three edictals represent a Brazilian government?s total investment of 19 million reais or 9 million dollars,approximately. Table 7 shows information considering the financial resources from FINEP for the developmentof these research projects, not taking into account tuitions and another sources of funds.

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Table 7. Information concerning the first three Prosab edictals.

Source: Adapted from Furtado et al., (2005). * Information about 33 projects from a total of 71 projects. (1)

Considering books, congress articles and periodics.

When observing the directly technological production for the sludge theme, in these 33 projects, we can find3 new products, 4 new processes, and 7 new methodologies, totaling 14 new products. Considering the transferof technology and its application in full scale, the researches related to the sludge topic somehow had influenceover 3.5 million people during 2004, mainly due to the use of the proposals made by Sanepar – Sanitationcompany of the state of Paraná.

Furtado et al. (2005) states that the research regarding wastewater and sludge has very consistent results.The human capital and material development were significant. These groups had important informationexchange and good relationship with the people involved, such as general sponsors, technological poles, andthe market. Concerning the scientific production about wastewater sludge, it was produced 13 articles insnational conferences, 2 articles in international conferences, 4 book chapter and 6 national books, withoutconsider thesis and dissertations that resulted from these projects.

There are several books that resulted from Prosab´s research program. Until 2003, the most important booktitles about sludge are as follows (original titles are in Portuguese):

- Solid residues from sanitation: Processing and final disposal – Edition 2 / 2001;

- Management and utilization of the wastewater sludge in agriculture – Edition 1 / 1999;

- Practical manual for biosolids composting – Edition 1 / 1999;

- Management of Non-mechanical stabilization lagoons – Edition 1 / 2000;

- General perception of treatment and final disposal of water treatment plant sludge – Edition 1 / 2000;

BRAZILIAN STATES WITH ESTABLISHED SLUDGE MANAGEMENT

São Paulo state sludge management.The State of São Paulo, located in the southeast region of Brazil, is formed by 645 municipalities with a totalpopulation of 40 million inhabitants. It is the Brazilian state with the highest population density and thebiggest industrial area.

Sabesp, São Paulo’s sanitation company, is present in 367 municipalities in this state, and it is responsiblefor planning, constructing and operating the water, wastewater, and industrial systems.

According to data from SNIS in 2005, the company attended 18 million inhabitants with wastewater treatmentsystem. The volume of collected and treated wastewater for the same year corresponds to 888,607 and 544,961million of cubic meters in one year, respectively.

Santos (2003) states that the main sewage system in the metropolitan area of São Paulo is formed by fiveintegrated systems, with WWTPs with corresponding names: ABC, Barueri, Parque Novo Mundo, São Miguel andSuzano. In the countryside of the state, there are some big WWTP like Franca WWTP (in Franca) and Lavapés WWTP(in São José dos Campos), while in the coastal region the largest system is the Bichoró WWTP (in Mongaguá).

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According to Sabesp?s information, approximately 90% of the sludge produced in the State of São Paulo islandfilled. The quota used in the agriculture represents approximately 10% of the total generated sludge. TheLavapés WWTP, is about to change its lime stabilization system and will start to use a system that usescomposting for sludge treatment.

Table 8 shows the main characteristics of the WWTP of the State of São Paulo as the main alternatives usedin stabilization, sanitizing, conditioning, dewatering and final disposal of the sludge produced .

Table 8. Sludge production and adopted processing alternative in the State of São Paulo.

In order to attend the requirements from the Environmental Control Company of the State of São Paulo (CETESB),Sabesp developed, in 1988, a Ruling Plan for sludge use and disposition in the metropolitan area of the city ofSão Paulo. This plan defined two main alternatives for sludge disposition: monofill sites and agriculture use.The use of landfill sites is linked to the sludge’s thermal drying, so the volumes to the site would be reduced.

Case study: Sludge management in the State of ParanáThe State of Paraná is located in the South of Brazil and it is formed by 399 municipalities, with approximately10 million inhabitants. According to Sanepar, in 2006, there were 2,722,193 connections to water and thesewage system had 1,386, 966 connections. Currently, the annual sludge production discarded by the WWTPis estimated in 120,000 m3.

The most important variables in the dewatering process are the sludge characteristics, available area andclimatic factors. The sludge drying beds generally produces good results with anaerobic stabilized sludge,easily obtaining 50% of total solids (TS) , with the possibility of reaching more than 70% of TS. As for themanual work and climatic factors, however, the results are not satisfactory. Generally, the conditions in the Westportion of the State of Paraná attend these requirements, which had made it possible to use the sludge dryingbeds in most of the WWTPs, from small to average scale. Table 9 presents the relation between WWTP scaleand the sludge processing alternative used in Paraná.

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Table 9. Dewatering process utilized in Sanepar considering the WWTP scale.

* Required area considering 15 kg TS/m2, dyring cycle 30 days (25 + 5 days for cleaning). **sludge drying beds.

The main alternative for reduction of pathogenic microorganisms in the sludge produced in the WWTPs inParaná, is the addition of lime , for pH control, and later controlled agriculture disposition. Sanepar recyclesthe wastewater sludge using agriculture, according to the procedures of control established by TheEnvironmental Institute of the State of Paraná (IAP).

Two good samples that could represent the model of Paranás sludge management are the Belém WWTP(biggest sludge producer in Paraná), with approximately 85 ton/day and 15 to 20% TS, resulting in an estimateof 2,600 ton/year of TS. The other sample is the WWTP in Foz do Iguaçu that produces approximately 150 tonST/year. This sludge is produced by 5 WWTPs and after dewatering in sludge drying beds, it is combined withsanitizing processing, stocking and, final disposition (agriculture).

The wastewater treatment used in the Belém WWTP is the aerobic process with extended oxidation. The sludgeremoved from the process, which has good stabilization condition, goes to the thickening, conditioning, andmechanical dewatering made by the dewatering press and centrifuge. The dewatered sludge is mixed withhydrated lime in dosages of 50% (as TS). The lime is stored in vertical silos equipped with automatic dosagesystem. The blend with the sludge is made by mixer with stripe axle ducts . After the mixing phase, the sludgeis transported to the storage yard. The data presented in Table 10 shows the average sludge characteristicsfor the Belém WWTP.

The agriculture use of the sludge requires an area of about 700 hectare / year. The selection of the area is madeby Emater – PR (Institute for Technical Assistance and Rural Extension – Paraná), that also performs theenvironmental monitoring, through an agreement. The transport is made through trucks with dumps. Thefarmer receives, without charges, the sanitized sludge in the area of application. Emater provides theequipment for application on the land, which is used attached to the farmers? tractors.

The medium rate application is about 8 ton TS/hectare, which varies according to the recommendation foreach crop, considering that the sludge variability for the same sludge is low. The sludge produced in theBelém WWTP, which has about 15 to 20% of TS, is characterized as semi-solid cake that needs specificequipments for its use. The main crops where the sludge is used are: corn (54%), oat (4%), turfgrass (30%),fruits (9%), beans (3%). Table 11 presents the average results observed with the Belém WWTP sludge use inthe production of corn.

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Table 10: Average sludge characterization for 17 lots from the Belém WWTP after lime addition.

Emater-PR, verified in essays developed in some properties in the municipality of Fazenda Rio Grande (PR),an increase in the productivity from 32% to 54% from 1994 to 1997. These important increase in theproductivity observed in these studies make evident the low technological level of these farmers, that generallydo not use any product for soil correction or fertilizer. In developed systems of agriculture production, theexpected agricultural responses due to the use of sludge are less significant. Although, in this cases, theadvantage is the reduction of the chemical fertilizers demand, specially nitrogen, besides physical-chemicaland biological improvement of the soil.

Although, in this cases, the advantage is the reduction of the chemical fertilizers demand, specially nitrogen,besides physical-chemical and biological improvement of the soil.

Table 11 – Corn crops production fertilized with wastewater sludge in comparison with chemical fertilization.

The wastewater treatment system in Foz do Iguaçu is made of 5 WWTPs. The wastewater treatment plants useanaerobic process, with systems that are similar to the UASB reactor, which produces a stabilized and thickenedsludge. The dewatering is made in sludge drying beds, with sludges of higher solid content than the onesdewatered mechanically, with about 50% of TS. The sludge from these WWTPs is transported to a managementsludge unit (UGL), next to the WWTP where it is subjected to the sanitizing, stocking and characterization. Inthis UGL, the hygienic process used is the addition of quicklime (mix of lime in a rate of 50% to sludgemeasured as TS). After the mixing process, the sludge is stocked in an appropriate area. The sludge whichpassed through the sanitizing process presents characteristics as shown in Table 12.

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Table 12: – Average sludge characterization for Foz do Iguaçu WWTPs after lime addition.

According to the studies developed in Foz do Iguaçu, the sludge was applied in Corn and Soy crops in twodifferent farmer´s properties. The volume of sludge produced in the city is enough for just 15 hectare area ofapplication per year. The sludge presented humidity of 26% (74% of TS) and solid consistence. Due to its moresolid characteristics, it was possible to use the same equipment used to application of lime on the land,commonly found in rural properties, with no need of more sophisticate equipment.

The wastewater sludge, in some cases, may contribute to the soil contamination with heavy metals. Thesemetals in the sludge have their origin in industrial activities. These heavy metals not only have negative effectson plants growing, but can also affect the soil biochemical processes. The organic matter decomposition,mineralization and nitrification are some of the processes that could be inhibited by heavy metals incontaminated areas (Tsutiya, 2001).

The heavy metals present in the sludge can be divided in two categories, depending on the risk that theyrepresent. Some examples of metals that are considered of low risk are: Mn, Fe, Al, Cr, As, Se, Sb, Pb and Hg.The potentially hazardous metals for men and animals are: Zn, Cu, Ni, Mo and Cd. Among these metals, someare essential micro nutrients for plants (Cu, Fe, Mn, Mo and Zn), and other have a benefic effect (Co and Ni).In order to use wastewater sludge in agriculture, great care should be taken when characterizing and evaluatingthe inflow wastewater and defining limits for some determined substances (Silva et al., 2001; Tsutiya, 2001).

In a study performed in the metropolitan area of Curitiba concerning the use of sludge in agriculture, Pegorini(2002) evaluated the heavy metals presence in bovine, swine and poultry manure. He found that theconcentration of Cu is slightly superior than Cr, Cd, Pb and Ni for the biosolids, as the result of industrialactivity. In the case of Zn, the values found in the manure are slightly superior in bovine and poultry, but lowerin swine . So, it can be supposed that the wastewater sludge does not offer greater health risks than theanimal manure that is frequently used in farms.

Table 13 presents the distribution results of the different variation ranges considering the maximum valuesadmitted in the IAP rule for agriculture use of wastewater sludge in Paraná for the elements Cu, Ni and Zn.For “class A” sludge in USA - USEPA Se and Pb, also for Pb and Ba related in CONAMA and finally for Cd andCr in the Brazilian Ministry of Agriculture.

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Table 13 – Percentual distribution of the samples, according to the normative references of limits and theaverage for WWTPs in the State of Paraná.

MAIN OBSTACLES FOR THE USE OF WASTEWATER SLUDGECurrently, the sanitation companies are in a very important moment concerning the adjustment of theirprocesses for the use of their sludge in agriculture. According to the resolution 375/2006 issued by Conama,sanitation companies have 18 months as of February 2007 to be adequate to the new regulations.

One of the greatest difficulties found by the sanitation companies is related to the verification of the sludgesanitation concerning the presence of specific viruses and organic micropoluents. These kind of analysis is notperformed bymost of the commercial laboratories, being restricted to some types of specific research in universities.

Another aspect of extreme relevance in the process of the use of sludge in agriculture is the integration ofmany people involved in the processes (sludge generation, processing, stocking, transport, soil incorporation),such as sanitation companies, rural production and technical assistance institutes, environmental controlcompanies, farmers, and people in general.

Due to this demand, there is a great need of integration for technical and operational cooperation amongcompanies, institutions and public administration involved in the process and the support from the farmersthat will receive the sludge.

Maintenance and reliability of defined processes are extremely important in order to reinforce the credibilityin new implemented programs. This way, the environmental education has essential importance to the gooddevelopment of this kind of programs and effectively promotes cultural and behavioral changes.

In this context, it should be emphasized that there is a great need for the changes in the cultural behavior offarmers from small and big properties, authorities, unions, so the access to information can make it possibleto give new information to these participants and develop the possibility of constructive discussion about thereal possibilities of this alternative. Another important cultural change is about the way people perceive thesludge disposition. Whereas it should be seen as an advantage as a new product, it is usually perceived as aproblem that people want to get rid of (Andreoli et al., 2001a).

This way, the WWTPs should be seen as an industry of biosolids and not just as way to treat wastewater.Furthermore, the evaluation of a system would not be limited just to the effluent quality, but also to its productsquality, like sludge quantity and characteristics .for the residues/products could be sold or supplied.

Even though the benefic characteristics of the sludge in the agriculture are clear, the technical rules for eachlocation should be respected in order to avoid negative impacts on the environment. In regions where the areafor agriculture is so vast, one of the logical alternatives is the use in agriculture.

FINAL CONSIDERATIONSThe great production of wastewater sludge in the urban centers and its destination is an environmental problemof extreme relevance and represents a great challenge.

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The subject complexity deserves to be outlined in Agenda 21, where, in the 21st chapter, treats specificallyabout the final disposal of sanitation residues. The recommendation indicates, initially, the measures thataim at the reduction of residue production, followed by alternatives of reusing and recycling and finally theadoption of measures for final disposal taking the environment into account.

Andreoli and Pegorini (2006) state that the use of wastewater sludge cannot be confused as a simple way forsanitation managers rid themselves of this problem, but in contrast, the recycling concept demands theadoption of technological alternatives that maximize the benefits through the use of beneficial componentsof the residues, carefully considering the environment and sanitary risks, to generate safe and economicalviable alternatives that will guarantee the sustainability of the process.

Considering the current numbers for urban of collection and wastewater treatment services, as well as theincreasing requirements for magnifying these services for the remain of the Brazilian population, a greatperspective of growth in the biossolids generation is verified in nationally.

In spite of the changeable composition, function of regional characteristics and of the processes where theyare generated, generally, biossolids present in their constitution elements of great value, making it possibleto use it as input in the agricultural processes. Wastewater sludge contains nutrients, essential elements forthe development of the plants (macro and microelements), and the organic substance, the basis forsustainability of soils and very few WWTP in Brazil have sludge contamination by heavy metals.

Currently, despite the Brazilian territorial characteristics offering a great agricultural potential to the country,the use of sludge in agriculture is low (about 15% of the wastewater sludge is used in agriculture). Accordingto the available estimates (Machado, 2001) a great amount of the sludge produced in the domestic territoryis designated to sanitary landfill sites.

It is valid to point out that the high indexes of the use of this alternative are not able to represent the definitesolution for the problem. In Brazil, the available data (IBGE 2007) indicates that only 30.3% of the units offinal disposal are sanitary forms of waste management. This means that the great majority of the Braziliancities (about 73% of the cities present population of up to 20.000 inhabitants) still make the final disposalof its residues through irregular dumps or landfill sites with little environment control.

Another aspect concerns the needed characteristics of biossolids conditioning for final disposal in landfill. Asdemonstrated in the experience of the State of São Paulo, the use of monofills for sanitation wastes is relatedto the necessity of draining and drying the sludge. This condition implies the use pf specific equipment toreach operational conditions not only for disposal of the residue but also for the reduction of the volumes tobe land filled.

As for the integrated biossolids management, sanitation monofills can be considered as an emergencyalternative for the cases where the agricultural use of sludge is not possible, either for the existence ofrestrictions regarding the quality of the sludge (e.g. possible industrial contaminations) or for otheradministrative and technical reasons (e.g. equipment out of order, contract renewal, adverse conditions of theenvironment for the application of the sludge).

It must be also reinforced that a landfill site needs several actions that will grant its environment protectionmaintenance (for a long time after being shut down) in order to guarantee the sanitary conditions of thistechnique, once it is basically constitutes one technique of residues stocking, not allowing the nutrients and/orenergy to cycle when compared with other alternatives for final disposal.

Despite the visible benefits of the agricultural use of the wastewater sludge as well as of the natural aptitudeof soils for agriculture, this practice still finds some obstacles for its implementation mainly when consideringthe aspects of logistics involved in the management of the sludge producing units: sludge cakes dewateringand conditioning , analysis of quality, storage, transportation, evaluation of the agricultural aptitude of theplace and incorporation to the soil (Andreoli et al., 2001b).

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Along with alternatives already established for final disposal, several lines of action have been studied as analternative to the beneficial use of biossolids among which we can outline: the use in forest plantations(forestry), reestablishment of degraded areas and substratum manufacture for seedlings.

Over the last years, Brazil has concentrated operational and scientific efforts for the management of thewastewater sludge produced in the treatment stations, however little attention has been given to themanagement of septage of in situ sanitation systems, such as domestic septic tanks. As mentioned initially,only 47.9% of the urban populations are served by services of wastewater collection.

From this point of view, due to the lack of guidelines and reliable management techniques and alternatives,neither from private initiative nor the public sector, septage management is, generally, not performed correctly.In some regions, the septage is directed to Sewage Treatment Plants, when existing, that accept this type ofresidue,. The majority of the wastewater produced however, is disposed without any technichal criteria - in thesoil, rivers and even as fertilizer in agriculture - risking population’s health and the environment quality.

Having this reality and considering that the state of art knowledge about septage still needs to be consolidated,Finep (Financier of Studies and Research) through Prosab?s Program published a specific edictal for thedevelopment of studies enclosing the different regions of the country. The study that involves five Brazilianinstitutions of research will, initially, develop studies of the septage produced by septic tanks, followed by theevaluation and the development of alternatives of treatment and disposal of this sludge.

REFERENCESAndreoli C. V., Lara A. I., Fernandes F. (Org). Reciclagem de biossólidos: transformando problemas em soluções(Biossolids recycling: transforming problems into solutions). Curitiba: Sanepar, Finep, 2001a. 2 ed. 288p.

Andreoli, C. V., Pegorini E. S., Fernades F. Disposição do lodo no solo. In: Andreoli C. V.; Sperling M. Von;Fernades F. Lodo de esgotos: tratamento e disposição final (Sewage sludge: treatment and final disposal).Belo Horizonte: Departamento de Engenharia Sanitária e Ambiental UFMG: Companhia de Saneamento doParaná, 2001b. 484p. (Princípios do tratamento biológico de águas residuárias; 6) 319-398p.

IBGE. Pesquisa Nacional de Saneamento Básico 2000 (National research of Sanitation2000).http://www.ibge.gov.br/home/estatistica/populacao/condicaodevida/pnsb/lixo_coletado/lixo_coletado109.shtm (acessed 15 march 2007).

Companhia de Saneamento Básico do Estado de São Paulo – SABESP. Gerenciamento de lodo de esgoto no Estadode São Paulo - Relatório Técnico (Sludge Management in the State of São Paulo – Technical Report). 2006.

Conselho Nacional do Meio Ambiente. Resolução N. º 375 de 29 de agosto de 2006. Define critériose procedimentos, para o uso agrícola de lodos de esgoto gerados em estações de tratamento de esgotosanitário e seus produtos derivados, e dá outras providências. Diário Oficial da República Federativa doBrasil (Official gazette of the Federative Republic of Brazil), 30 agosto, 2006.

Furtado A. T., Bonaccelli M. B., Bin A., Miglino M. A. P., Paulino, S. Avaliação de Resultadose Impactos doProsab (Elavuation of Results and Impacts of PROSAB Program). 2005.

Machado M. F. de S. A situação brasileira dos biossólidos (The Brasilizian situation of biossolids) .Dissertação (Mestrado). FEC - Universidade de Campinas. Campinas, 2001. 828 p.

Pegorini E. S., Andreoli, C. V. Introdução. In: Andreoli, C. V. (coord.) Alternativas de Uso de resíduos dosaneamento (Alternatives of Use of sanitation residues). Rio de Janeiro: ABES, 2006. 417 p.

Pegorini E. S., Hoppen, C., Tamanini C. R., Andreoli, C. V. Levantamento da contaminação de lodo deestações de tratamento de esgotos do estado do Paraná: II Metais Pesados. In: Simpósio Ítalo Brasileiro deEngenharia Sanitária e Ambiental, 8., 2006, Fortaleza. Trabalhos Técnicos (Technical Papers) (. Fortaleza:SIBESA, 2006. 1 CD-ROM.

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