Integrated solutions for urban runoff pollution control in Brazilian metropolitan regions

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1 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 Integrated solutions for urban runoff pollution control in Brazilian metropolitan regions A. C. D. Morihama, C. Amaro, E. N. S. Tominaga, L. F. O. L. Yazaki* M. C. S. Pereira, M. F. A. Porto 2, P. Mukai and R. M. Lucci Fundação Centro Tecnológico de Hidráulica - FCTH. Av.Pedroso de Morais, 69 cj.57, 549-, São Paulo, SP, Brazil 2 Departamento de Hidráulica e Engenharia Ambiental da Escola Politécnica de São Paulo, Av. Luciano Gualberto, 38 travessa 3, 558-, São Paulo, SP, Brazil *Corresponding author, luizorsini@fcth.br ABSTRACT One of the most important causes of the poor water quality of urban rivers in Brazil is the low efficiency of wastewater network system and its storm waters pipes unplanned interconnections. Also, the diffuse pollution, which is a considerable parcel of pollutant load discharge in urban water bodies, is a problem which hasn t been considered in the remediation water plans in Brazil. Therefore, the higher challenge faced today by sanitation systems managers in Brazil, is to find solutions for recover the quality of urban water bodies through a more efficient and low cost technology. This article investigations are based in the largest daily quality monitoring already held in the country performed in Pinheiros River, in São Paulo. It evaluates d water quality parameters and the diffuse pollution effects during rain events of one of the main rivers of São Paulo Metropolitan Region. It also proposes integrated solutions for the water pollution control, based on European experience in urban water management and evaluates the performance of several wastewater and storm waters systems conceptions, comparing them with separate systems that are being used in Brazilian cities since the origin of sanitary systems in the country. KEYWORDS diffuse pollution, combined systems, separated systems, sewage and drainage technology urban water management, water quality INTRODUCTION The first actions undertaken in the XIX century, for Brazilian cities sanitation, emphasized the implementation of discharge systems, based on the principle that was necessary to take the contaminated water away from the population. The final destinations of these waters were streams, rivers and lakes that received their negative and progressive impacts. With the developing and implementation of sewerage separate systems, it was expected that urban rivers water quality problem could be resolved. It actually didn t happened in Brazil. The origin of this problem in Brazil is the low efficiency of wastewater network system and its storm waters pipes unplanned interconnections (Yazaki et al., 27). Despite the huge investments made by the government and sanitation companies in recent years, water bodies of the cities continue to present high levels of pollution. Also, the diffuse pollution, which is a considerable parcel of pollutant load discharge in urban water bodies, is a problem which Yazaki et al.

2 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 hasn t been considered in the remediation water plans in Brazil. Therefore, the higher challenge faced today by sanitation systems managers in Brazil, are to find solutions for the pollutant discharge attenuation in urban water bodies through a more efficient and low cost technology. This article proposes integrated solutions for the water pollution control, based on European experience in urban water management. It evaluates the performance of several wastewater and storm waters systems conception, comparing it with the traditional separate systems that are being utilized in Brazilian cities since the origin of sanitary systems in the country. METHODS Daily monitoring of Pinheiros and Tietê Rivers. A daily monitoring of Pinheiros and Tietê Rivers was performed during two and a half years in the Avaliação da Qualidade das Águas do Sistema Pinheiros-Billings com o Protótipo de Flotação project (Pinheiros Billings System Water Quality Assessment with Flotation Prototype, FCTH, 2). Pinheiros and Tietê are the main rivers which drain São Paulo Metropolitan Region (SPMR) with about 9 million residents. The project became the largest quality monitoring program already held in the Brazil with more than 2 thousand water quality analysis, including 2 pollution indicators with 5,668 samples, collected in 53 different points in these water bodies (Figure ). For the water quality analysis in rain events, an automatic sampler was installed in Pinheiros River. This sampler performed automatic water sampling at pre stipulated time steps. Tietê and Pinheiros rivers have a special characteristic. In the early 2 th century São Paulo began the exploration of its water resources for electricity production taking advantage of the height difference between the city plateau and the Atlantic coast (about 7 meters). This system was possible by transferring Tiete and Pinheiros waters to Billings reservoir. Figure. Monitored points location Comparative Analysis of Pinheiros and Tietê Rivers. For assess any significant difference between Tietê and Pinheiros Rivers sample analysis results, the following statistic tests were realized for a significance level (p-value) of %: 2 Solutions for urban water bodies pollution control

3 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 Significance Test of equality between two means: A null and an alternative hypothesis for a population parameter are admitted. Based on sample information, the statistical test for reject the null hypothesis in favor of alternative hypotheses or do not reject the null hypothesis is realized. The tests considered only the p-value error, i.e., the probability to reject the null hypothesis being this true (Martins, 2). Nonparametric Test of medians: The non-parametric tests don t rely on assumptions that the data are drawn from any particular distribution. The test gives information if two independent groups come from populations with the same median (Martins, 2). Surface Runoff Analysis: To evaluate the surface runoff effects after a rain event in the receiving water body the following parameters were calculated (Brites, 25): Event Mean Concentration (EMC) where: EMC (mg/l); M = total pollutant mass during the event (g); V = total volume during the event (m³); t = time (s); Ct = concentration in t time (mg/l); Qt = flow in t time (m³/s); t = time interval (s). Difuse Load (CD): where: CD (g/s); CD base = diffuse load characterized by the water quality in the closest day event Wash Load Analysis: To evaluate the wash loads a Pollutant Mass Distribution x Runoff Volume methodology, described by Gupta & Saul (996a) was used. The variability of the pollutant mass rate which is transported during a rain event in the drainage network can be described by two curves: hydrograph Q(t) and pollutograph C(t) for each considered pollutant. If these curves, called M(V) curves, have a 45º slope, a uniform distribution is admitted for the pollutant during the event. When M(V) curves are above the bisector, curve > 45º, wash load occurs. When the curves are below the bisector, curve < 45º, the wash load do not occurs (Brites, 25). RESULTS AND DISCUSSION The lately wastewater system improvements implanted in São Paulo didn t reduce the water pollution levels on the two main rivers of the city. The Programa Córrego Limpo (Clean Stream Program), for example, which had the objective to reverse the streams degradation, from March 27 to late 2, recovered 96 of streams with an investment of R$ 35.6 million (Programa Córrego Limpo, 2). As shown in Figure 2, despite the high investments of project, only 9% the SPRM area was recovered. This didn t positively impact the water quality of Pinheiros and Tietê Rivers, as shown the Figures 3 and 4. The average DBO 5 concentration, for instance, had an increasing tendency between 5 mg/l to 6 mg/l, during the monitoring period, from 27 to 2 for the Pinheiros and Tietê Rivers. A precise evaluation of water pollution dynamics in SPMR was possible after monitoring of Pinheiros and Tietê Rivers. According to statistics tests, showed in Table, Pinheiros and Tietê Rivers water quality is the same for several water quality parameters. Yazaki et al. 3

4 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 Figure 2. Recovered Areas by Projeto Córrego Limpo BOD 5 (mg/l) Pinheiros River 6/8/7 4//7 22/2/8 /6/8 9/9/8 8/2/8 28/3/9 6/7/9 4//9 22// Figure 3. Variation of BOD 5 Concentration in the Pinheiros River BOD 5 (mg/l) Tietê River 6/8/7 4//7 22/2/8 /6/8 9/9/8 8/2/8 28/3/9 6/7/9 4//9 22// Figure 4. Variation of BOD 5 Concentration in the Tietê River Table. Results of Statistical Tests between the waters of the Pinheiros and Tietê Rivers Quality Parameters Statistical Tests: Pinheiros River x Tietê River Significance Test of two Means Nonparametric Test of Medians BOD 5 Not Different Equal COD Not Different Equal N-NH 3 Not Different Different DO Not Different Equal TP Not Different Equal N-NO 3 Not Different Equal N-NO 2 Not Different Equal Escherichia Coli Not Different Different The pollutograms monitored during rain events in Pinheiros basin, allowed to take important conclusions about diffuse pollution, which hasn t been considered in the sanitation plans development. Table 2 presents Events Mean Concentration (EMC) for six water quality parameters monitored during the rain events. It was observed a high EMC variability between these events and a pattern was not found. This is a result of the intrinsic characteristic of each event and also a reflex of the occurrence of rain in previous days. 4 Solutions for urban water bodies pollution control

5 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 Table 2. Event Mean Concentration (EMC) Quality EMC (mg/l) Parameters 2/8/9 3/9/9 6/9/9 28/9/9 6//9 7//9 22//9 26//9 5//9 TOC BOD COD TP N-NH TSS Quality EMC (mg/l) Parameters 2//9 2//9 24//9 26//9 /2/9 3/2/9 7/2/9 6/2/9 26/2/9 TOC BOD COD TP N-NH TSS Studies performed around the world, shows that the diffuse pollution contributes with a considerable pollutant charge of the urban rivers. This pollutant charge can reach more than 3% of the total charge (FUSP, 29; FCTH, 2). According to Table 3 and Figure 5, diffuse pollution load contribution in Pinheiros basin is higher than the presented in literature. Table 3. Calculated Load from 2/8/29 to 28/2/29 Quality Parameters Load from 2/8/29 to 28/2/29 Total (ton/day) Diffuse pollution (%) Other Sources (%) TOC BOD COD TP N-NH TSS Ton/day Load from 2/8/29 to 28/2/ TOC BOD5 COD TP N-NH3 TSS Total Diffuse Pollution Other Sources Figure 5. Calculated Load from 2/8/29 to 28/2/29 Yazaki et al. 5

6 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 Figures 6 to 9 show the wash loads M(V) curves of monitored rain events. In most events pollutant loads were not uniformly distributed along the runoff volume. Accumulated Mass / Total Mass Figure 6. TOC M(V) curves monitored events Accumulated Mass / Total Mass TOC COD Accumulated Volume/Total Volume Figure 8. COD M(V) curves monitored events 2/8/29 3/9/29 6/9/29 28/9/29 6//29 2//29 7//29 22//29 26//29 5//29 2//29 2//29 24//29 26//29 /2/29 3/2/29 7/2/29 6/2/29 26/2/29 2/8/29 3/9/29 6/9/29 28/9/29 6//29 2//29 7//29 22//29 26//29 5//29 2//29 2//29 24//29 26//29 /2/29 3/2/29 7/2/29 6/2/29 26/2/29 Accumulated Volume/Total Volume Accumulated Mass / Total Mass BOD Accumulated Volume/Total Volume Figure 7. BOD 5 M(V) curves monitored events Accumulated Mass / Total Mass /8/29 3/9/29 6/9/29 28/9/29 6//29 2//29 7//29 22//29 26//29 5//29 2//29 2//29 24//29 26//29 /2/29 3/2/29 7/2/29 6/2/29 26/2/29 Figure 9. TSS M(V) curves monitored events TSS 2/8/29 3/9/29 6/9/29 28/9/29 6//29 2//29 7//29 22//29 26//29 5//29 2//29 2//29 24//29 26//29 /2/29 3/2/29 7/2/29 6/2/29 26/2/29 Accumulated Volume/Total Volume A separated system where all runoff pollution loads are thrown into the water bodies without treatment, which is assumed in SPRM, doesn t give an adequate environmental protection; this protection is normally less than an offered by a combined system well planed (Paoletti, 27). The results show that with the use of combined systems with such devices to drive the most polluted parcel of the urban runoff, including first flush and sewage, to the treatment plant, similar to the European systems (Figures and ), gives environment protection to the receiving water bodies similar to obtained with a separated system with rain water treatment, like showed in Figure 2 (Paoletti e Papiri, 27). Thus, a combined system in a disorganized urban area, like SPMR, is in general more economic than a separate system, in terms of investments and operation expenses. A complete and effective separation of sewage from rain water in existing network, planned like separated, but operated, in fact, like combined, involves too high costs, beyond technical and administrative difficulties. The decision to separate combined networks should be taken only in case when decisive advantages could be reached or in situation where this solution is essential, which rarely happens. 6 Solutions for urban water bodies pollution control

7 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 E E ETE E E ETE ETE R R ETE AP Figure. Combined system with spillway Figure. Combined system with spillway and reservoir Figure 2. Separated system with wastewater and storm water treatment E Water Body Stormwater Network Sewerage or Combined System Spillway R ETE ETE AP th E Flush Reservoir Wastewater Treatment Plant th Flush Treatment Plant Simulations done in previous researches (Yazaki, 27) indicate that the reduction of pollution loads would be more than 8% with the use of first flushes reservoirs, with less investments regarding the existing separated systems recovering plus first flush treatment. According to the present simulations (Table 4 and Figure 3), with the introduction of hypothetical th flushes reservoirs designed for the first 5 or mm of rain, a 5% reduction in diffuse load discharge in Billings Reservoir can be achieved. The results obtained were lower than those from literature, mainly because of the buffer effect in large basins (Pinheiros basin area is km 2 ). Table 4. Diffuse Load depletion simulation using th Flush Reservoir Diffuse Load from 29/8/2 to 29/2/28 Quality Parameters without reservoir (ton) % reduction with reservoir for 5 mm % reduction with reservoir for mm TOC BOD COD TP 2 42 N-NH TSS 2 28 Ton/day Load from 2/8/29 to 28/2/ TOC BOD5 COD TP N-NH3 TSS Diffuse Pollution without reservoir Diffuse Pollution with reservoir for 5 mm Diffuse Pollution with reservoir for mm Figure 3. Diffuse Load depletion simulation using hypothetical th Flush Reservoir Yazaki et al. 7

8 2 th International Conference on Urban Drainage, Porto Alegre/Brazil, -6 September 2 CONCLUSION Considering the national sanitary situation, where most of the wastewater and drainage systems work as non official combined sewer systems, even in consolidated urbanized regions, the employment of pollution control systems, similar to the ones analyzed in this article, could be an alternative to be considered, at least as a first step to achieve rivers water quality goals. Therefore, the evaluated case, even with the use of a simplified mathematical process, suggest that it is worth developing deeper and more detailed studies on pilot basins, with the objective of improve urban creeks and rivers water quality. From the sanitation service point of view, the practice has proof that rain water and sewage systems integrated operation is more efficient and economic. When different managers are responsible to the operation of drainage and sewage systems, the operation cost of were higher compared to integrated operation. In Europe, generally, sewage collection and drainage services are integrated and performed by only one manager. In major European countries, in both cases, the possibility to plan, design, implement and operate the drainage separately of the sewage does not exist. This was the best solution to attend the severe European Union environment guidelines, which states that water ecosystems must be recovered until 26. REFERENCES Artina, S. et al. (997). Sistema di Fognatua Manuale di Progettazione. Hoepli and CSDU, Milan. Brites, A. P. Z. (25). Avaliação da Qualidade da Água e dos Resíduos Sólidos no Sistema de Drenagem Urbana. Departamento de Engenharia Civil. Master Dissertation. Universidade Federal de Santa Maria, Rio Grande do Sul, Brazil. Fundação Centro Tecnológico de Hidráulica (2). Avaliação da Qualidade das Águas do Sistema Pinheiros- Billings com o Protótipo do Sistema de Flotação, Final Report vol. to 4 and annexes, Fundação Centro Tecnológico de Hidráulica, São Paulo, BR. Fundação Universidade de São Paulo (29). Plano da bacia hidrográfica do Alto Tietê. Final Report vol. to 4 and annexes, Fundação Centro Tecnológico de Hidráulica, São Paulo, BR. Fundação Centro Tecnológico de Hidráulica and Centro Studi Idraulica Urbana (2). Sistemas integrados de drenagem: águas pluviais e esgotos. FEHIDRO, São Paulo, no prelo. Gupta, K. and Saul, A.J. (996a). Specific Relationships for the First Flush Load in Combined Sewer Flows. Water Resource, 3(5), Margaritora, G. and Paoletti, A. (27). La Separazione delle Acque nelle Reti Fognarie Urbane. CSDU, Milan Martins, G. A. (2). Estatística Geral e Aplicada. Atlas, São Paulo. Paoletti, A. and Papiri, S. (27). Sistemi fognari unitari e separati: aspetti funzionali e ambientali. in: Separazione delle acque nelle reti fognarie urbane. Atti della giornata di studio. CSDU, Roma. Programa Córrego Limpo. website, visited April 2. Yazaki, L. F. O., Haupt, J. P. O. and Porto M. F. A. (27): Uso Potencial de Sistemas Mistos de Esgotos e Águas Pluviais para Redução da Poluição Hídrica em Bacias Urbanas. In: 7 th Simpósio Brasileiro de Recursos Hídricos, São Paulo, São Paulo, November 27. CD-ROM, Anais ABRH. 8 Solutions for urban water bodies pollution control