Iwa international Specialist Conference

ABSTRACT

The Greater Moncton Sewerage Commission’s (115 000 m³/d) advanced, chemically assisted primary wastewater treatment facility in New Brunswick, Canada, has developed an integrated, long term, sustainable, cost effective programme for the management and beneficial utilization of biosolids from lime (alkaline) stabilized raw sludge as part of its overall long term Wastewater Management Strategy. The paper will provide practitioners and researchers with insight into a successful Canadian “wastewater sludge as a resource” programme.

Located in the Southeastern part of the Province, Greater Moncton encompasses the Town of Dieppe, the City of Moncton and the Town of Riverview. The Greater Moncton Sewerage Commission’s Wastewater Treatment Facility services an amalgamation of nearly 100,000 people and at the same time handles and processes septic wastes from large surrounding rural areas.
The liquid stream of the wastewater treatment facility consists of a chemically assisted primary treatment process dealing with large flow variations of the municipal’s combined sewage collection system. Sludge pre-treatment with liquid lime and centrifuge dewatering are included along with advanced automation and management strategies. Subsequent lime stabilization of the cake, conveyance, on-site storage and odour control are discussed followed by an indepth discussion of the biosolids as a resource programme, namely: composting, mine site reclamation, landfill cover, land application for agricultural use, tree farming, sod farm base as a soil enrichment and topsoil manufacturing. The paper relates how the Commission has successfully identified and developed biosolids uses and partners that take advantage of the local geography and its needs, crops grown and in the case of composting, the available amendment materials. All activities are based on the principle of sustainability and the many successful projects completed, effectively promote more varied uses of the product and continuously increase its acceptance. The paper also addresses: the issues of metals, pathogens and organic compounds, the quality control programme and the regulatory policy requirements respecting the use of biosolids in the Province of New Brunswick. Capital and operating costs for biosolids processing and reuse programmes are presented.
Research on the removal of heavy metals from the Wastewater Treatment Facility sludge is described as a potential long term strategy, should such be required, at the Greater Moncton Wastewater Treatment Facility in the future. A biological process known as BIOSOL was developed in the environmental engineering laboratories of the University of Toronto, Canada to remove heavy metals and destroy pathogens in wastewater treatment plant sludge. Primary, secondary or digested sludges are amenable to this treatment but it is most effective with raw primary sludge as in the Greater Moncton Wastewater Treatment Facility. Even though metal concentrations have always met regulatory limits for applications on agricultural land and for land reclamation, future plans focuses on composting which may require lowering of certain heavy metal if high grade composts are to be marketed. The research and pilot work described indicate that the metals can be biologically dissolved at low pH and removed. Possibilities and challenges related to scale-up are presented.
The Commission has maintained a close working relationship with the Université de Moncton, New Brunswick, Canada for carrying out evaluations and laboratory analysis of raw sludges, lime stabilized biosolids and compost derived from biosolids. An ongoing cooperative research project with the Université de Moncton, which was initiated in 2001 with the aim of producing an efficient growing medium using plant biosolids compost and soil is described. With the limited availability of quality topsoil and the need for increased protection of farmland in New Brunswick, the Commission sees this utilization of biosolids as one of the keys to sustainability. Various mixtures of plant biosolids compost with low quality soil are being examined in terms of germination rates, growth rates, resulting bacterial concentration, as well as heavy metals. The results of the first phase of this new research initiative are discussed.
Integration, approach to sustainability and “cumulative effects” as part of the overall biosolids management strategy are also discussed. These components are essential to the incorporation of an integrated and sustainable approach the “wastewater sludge as a resource programme” as part of the Greater Moncton Sewerage Commission’s overall long term Wastewater Management Strategy that provides what is believed to be a unique approach to biosolids management in Canada.


Keywords: biosolids, biosolids strategy, wastewater sludge as a resource, sludge management, lime stabilization, alkaline stabilization, heavy metals removal, beneficial use, integration, cumulative effects, sustainability

80.

PRODUCTION AND FINAL DISPOSITION

OF THE SEWAGE SLUDGE IN BRAZIL
Cleverson V. ANDREOLI, Dr.

Eduardo S. PEGORINI, MSc

Sanitation Company of Paraná (SANEPAR)

Rua Engenheiro Rebouças, 1376 CEP. 80215 - 900, Curitiba, Paraná, Brazil

Tel: [phone] 330 3238

e-mail.: [e-mail]

1. 
   Introduction
   

The final disposal of the sewage sludge comes characterizing as one of more relevant urban ambient problems of the present time, and that it grows daily in such a way in countries developed how much in those in development, as reflected of the magnifying of the sanitation services.

Beyond its economic importance, and the sufficiently complex and problematic operation, the disposal final of the sewage sludge presents significant impacts on the environment, many times exceeding the extension limits of the Waste Water Treatment Plant. Even so the sludge represents volume of only 1% to 2% of the treated sewage, its management is complex and expensive, involving in general 20% and 50% of the operational costs of a Waste Water Treatment Plant.

2. 
   Collection of Sewage and Production of Sludge in Brazil.
   

In Brazil, the question represents an emergent problem and with perspectives of fast aggravation due the time that the sewage collection and treatment system are being implanted and operated. Data of the IBGE (Instituto Brasileiro de Geografia e Estastística, 2000) point that, in Brazil, currently 85,25 % of the urban population are supplied with treated water, while only 40,12 % have sewage collection (approximately 55 million inhabitants). From the total volume of collected sewage, less than 40% are properly treated.

The evolution forecasting for sewage treatment and sludge production in Brazil is a lot difficult, in function of the development discrepancies and population growth in several country's regions. As reference, considering the index of sewage collection currently (55 million hab.), the perspective of sludge production to be disposed daily is between 1.100 to 1.300 tons of dry sludge.

In the biggest urban centers of the country the problem becomes still more critical. The esteem of sludge production, considering only the currently treated sewage in these cities, is of around of 630 d.m./day t, pressing the society and the authorities for an urgent problem in these regions: the lack of definition of an technique alternative, economic and ambiently adjusted for final disposal of the sludge. But the metropolitan São Paulo area, concentrates today around than 15 million inhabitants, that would produce 540 daily t d.m. of sludge, from 2005.

2. 
   Quality of the Sludge and final Disposal in Brazil.
   

The situation of the Brazilian's sanitation companies in relation of the final disposal in the treatment of waste water was raised by BONNET (1995) in all the units of the federacy. The consultation disclosed that one concessionaire launched the sludge directly into the rivers, two concessionaires practiced the oceanic disposal and six concessionaires used some forms of agricultural land application. The research still disclosed that two companies developed studies of sludge recycling: Rio Grande do Sul and Federal District.

In 1997, research carried through for LARA it pointed high orientation of the States of Rio de Janeiro and São Paulo to the disposal of sludge in landfill, mainly because the low quality of the sludges produced in those States, resulting from the mixture of effluent of industrial origin in the nets of public collection. Fact that seems to have been reverted in São Paulo, due the intensification of the studies around the recycling at the last years.

Currently the destination of the sludge in Brazil have great disparity. Normally the sludge is disposed in landfill, exclusive or in co-disposition with garbage, lagoons or deposits next to the Waste Water Treatment Plant, in the ocean, incinerate or used in agriculture. The CAESB (Company of Water and Sewage of Brasilia, DF), dispose 100% of the sludge of sewage in agriculture, while the SABESP (Company of Basic Sanitation of the State of São Paulo) dispose 100% of the sludge produced in the great São Paulo city in landfill.

In the Federal District, the sewage sludge is used in agriculture since years 60, together to the implantation of first the Waste Water Treatment Plant operated by the CAESB (Company of Water and Sewage of Brasilia), but only in 1995 lines of direction and orientation that guaranteed the quality and the security of the process had been defined. In 1997, in the State of São Paulo, the SABESP developed a managing plan where diverse alternatives for final disposal of the sewage sludge had been evaluated. The alternatives identified as of better potential for the region had been: landfill exclusive, agricultural use and incineration. Today the interior of the state comes recycling almost all the sludge produced, with detach to WWTP of Franca, the biggest, applying 4,5 t d.m. daily of sludge produced on farm land, registered as fertilizer agriculture.

In Paraná State, the agricultural recycling has initiated in 2000, in the capital, Curitiba, foreseeing initially reutilization of 50 % of the 10 t d.m. produced daily in the city of 1,5 million inhabitants. Currently the recycling program comes finding difficulty to attend the demand of sludge from farmers, with the recycling of almost 100% of the produced sludge. The program comes extending also to the interior of the State, with a perspective of reutilization of all the sludge produced in Parana.

In the State of Espírito Santo, the currently production of sludge is mainly concentrated in the region of Vitória, and the accumulation comes characterizing itself as one of the main problems in the operacionalization of WWTP. Between the alternatives of final disposal in analysis, recycling in agricultural land has been evaluated in special.

In Rio Grande do Sul State, there are advanced studies approaching the use and the definition of criteria for recycling the sludge of WWTP in agricultural ground.

2. 
   Ambient and Perspective impacts of the Recycling of Sludge of Sewage in Brazil.
   

For the sanitation sector, the beneficial use of sewage sludge represents an alternative of great reach for a serious problem and that tends to increase in the next years. Among the options for final disposition, the recycling in agriculture is distinguished in the Country as the alternative most promising under the ambient and economic aspects, beyond recognized technical as a definitive solution for the question, for transforming a residue into a fertilizer.

The agricultural use of the sludge in Brazil contributes for a sustainable agriculture, supplying organic matter, nutrients and reducing the soil erosion, consequence of the climatic conditions and the inadequate use practiced in Brazil.

This process demands however, the definition of criteria to guarantee the security of use and assure a lasting relation enter the companies of sanitation and the farmers, beneficiary potentials of the activity. The recycling in agriculture demands the production of a high quality fertilizer, guaranteeing the adequacy of the product to the agricultural use, the definition of restrictions of use to soil and alternative techniques that provide to the agriculturist biggest productivity and lucrativeness with environment and sanitation security.

The land application programs legally supported currently in Brazil proportionate satisfactory results for farmers, many times resulting high productivity, without however affecting the environment adversely. This programs are result of three big research networks developed in Brazil along the last 15 years, the SANEPAR land application of sludge research, the PROSAB and the SABESP research networks.