Microbiological composition of sludge generated in water treatment plants

Composição microbiológica do lodo gerado em estações de tratamento de água

Abstract

Studies that focus on the microbiological composition of water treatment plants (WTP) sludge, as well as its pathogenicity, are extremely necessary, especially with regard to environmental regulations, where the microbiological characterization of WTP waste can encourage new policies related to its management. In Brazil, few studies address WTP sludge, which, in general, is classified as non-hazardous and non-inert waste, with the microbiological characterization of this material being little explored. This case study performed the microbiological characterization of sludge samples from two WTPs located in the state of São Paulo, before and after the centrifugation process. The determination of microbial density and morphology, Gram staining, and the identification of the presence of total and thermotolerant coliforms were performed with samples produced in two different years, in WTPs that used different coagulants (liquid aluminum sulfate or polyaluminum chloride and ferric chloride). Results were evaluated along with the physicochemical analysis of the composition of this waste. The presence of microalgae and protozoa in non-centrifuged WTP sludge and the presence of total and thermotolerant coliforms in WTP sludge before and after centrifugation are among the main results of this study.

Keywords: beneficial use; microbiological composition; water treatment plant sludge

Resumo

Estudos que tenham como foco a composição microbiológica do lodo de Estação de Tratamento de Água (ETA), bem como sua patogenicidade, são extremamente necessários, principalmente em relação às regulamentações ambientais, onde a caracterização microbiológica dos resíduos de ETAs podem incentivar novas políticas relacionadas ao seu gerenciamento. No Brasil, poucos estudos abordam o lodo de ETA, que, em geral, é classificado como resíduo não perigoso e não inerte, sendo pouco explorada a caracterização microbiológica desse material. Nesse sentido, este estudo teve como objetivo, realizar a caracterização microbiológica de amostras de lodo de duas ETAs localizadas no estado de São Paulo, antes e após o processo de centrifugação. A determinação da densidade e morfologia microbiana, coloração de Gram e a identificação da presença de coliformes totais e termotolerantes foram realizadas com amostras produzidas em dois anos distintos, em ETAs que utilizaram diferentes coagulantes (cloreto férrico e sulfato e alumínio). Os resultados foram avaliados juntamente com a análise físico-química da composição deste resíduo. A presença de microalgas e protozoários no lodo não centrifugado da ETA e a presença de coliformes totais e termotolerantes no lodo da ETA antes e após a centrifugação estão entre os principais resultados deste estudo.

Palavras-chave: composição microbiológica; lodo de estação de tratamento de água; uso benéfico

1. INTRODUCTION

Access to a safe water supply is a fundamental right of citizens and essential to ensure adequate health and housing conditions, since water can directly or indirectly transmit diseases to a large number of people due to lack of hygiene, contact with polluted water, or to the presence of pathogenic organisms (Brasil, 2019; Howe et al., 2017; Heller and Pádua, 2010) . In this sense, water treatment plants (WTPs) are necessary, as they guarantee the production of water in accordance with the quality standards required for human consumption in different territories (Brasil, 2021; Who, 2017).

The water treatment process in WTPs involves a combination of different technologies selected according to the characteristics of the raw water. Among the treatments used in Brazil, the most common is the conventional treatment, which includes the processes of coagulation, flocculation, decantation, filtration, and disinfection, and requires the addition of chemical products (IBGE, 2020; Howe et al., 2017). This treatment produces waste, which is called WTP sludge. Its composition includes solid, organic, and inorganic substances from raw water (for example, bacteria, viruses, algae, organic particles in suspension, colloids, clay, silt, sand, iron, calcium, magnesium, and manganese), as well as aluminum hydroxides from the addition of chemical products and conditioning polymers used in the treatment (Grandin et al., 1993; Marques et al., 2000). In general, WTP sludge has different characteristics and properties, depending essentially on the conditions of the raw water, dosage of chemical products, and technology used in the treatment (Achon et al., 2013).

In Brazil, WTP sludge is classified as solid waste and commonly classified as Class II A waste (non-inert and non-hazardous), so the release in natura into surface waters and soil is prohibited (Brasil, 2010; (IBAMA, 2012; (ABNT, 2004a). This waste must be treated and disposed of within the legal criteria established in the country, but the steps to treat this sludge usually involve high costs. Thus, in most cases, WTP sludge is released into water bodies without treatment, causing significant environmental impacts (Achon et al., 2008; Brasil, 2010).

The search for economically viable and environmentally advantageous alternatives for the final disposal of WTP sludge and its use is still a global challenge. Disposal in landfills, use in composting, manufacture of materials in civil construction, and composition of some types of pavement are among the alternative methods (Richter, 2001; Di Bernardo et al., 2012, Da Silva et al., 2017; Alves and Marques, 2021).

WTP sludge is a heterogeneous by-product and its composition varies according to the raw water quality, the applied water treatment and the chemicals used (Bernegossi et al., 2022). With regard to raw water, it can be influenced by increased urbanization, untreated wastewater discharges (eg domestic and industrial), soil pollution, deforestation, agriculture, among other changes in land use (Boretti and Rosa, 2019; Bernegossi et al., 2022). All over the world, the surface raw water purification processes use chemical coagulants to improve solid-liquid separation, where Al and Fe salts are added mainly as coagulants during the treatment process to remove colloidal and suspended impurities. In this way, these impurities together with the coagulant products also constitute the waste generated in the WTPs (Ahmad et al., 2017; Nayeri and Mousavi, 2022).

To enable the safe handling and use of WTP sludge, assessing the presence of microorganisms in its composition and the possible associated risks is essential (Acquolini, 2017; Zhao et al., 2019; Kristanti et al., 2022). Water treatment plants are an unexpected source of biodiversity in terms of environmental microorganisms and their interactions at the community level are still poorly understood, where the heterogeneous and seasonal composition of water treatment plant (WTP) sludge must be specifically assessed for each water treatment plant (Bruno et al., 2017; Rodgher et al., 2023).

In this sense, studies that focus on the microbiological composition of WTP sludge, as well as its pathogenicity, are extremely necessary, especially related to environmental regulations, since the microbiological characterization of waste from WTPs can encourage new policies related to their management, where the absence of WTS-specific guidelines currently allows reuse of the WTS without any restrictions (Ahmad et al., 2017; Giglio and Sabogal-Paz, 2018; Bernegossi et al., 2022). Several studies address the microbiological diversity present in WTP sludge, showing the importance of microbiological characterization, especially related to close contact with workers, which can represent a risk of infection (Makovcova et al., 2015; Giglio and Sabogal-Paz, 2018; Xu et al., 2018; Ullmann et al., 2019; Ranković et al., 2020;Wang et al., 2021; Bernegossi et al., 2022).

Thus, this study presents the microbiological composition of sludge produced in two WTPs in the state of São Paulo, before and after the centrifugation process, showing the human and environmental risks of the handling, recycling, and final disposal of the sludge, depending on of its physicochemical and biological compositions and the need for evolution of Brazilian regulations to enable the beneficial use of this waste.

2. METHODOLOGY

2.1. Contextualization

In this study, the sludge produced in two WTPs located in the state of São Paulo, Brazil (WTP 1 and WTP 2), which perform surface water capture and make the water potable to meet the Brazilian quality standard (Brasil, 2021), was evaluated using treatments with the stages of coagulation, flocculation, decantation, filtration, and disinfection (pre- and post-treatment), fluoridation, and pH correction. These stages produce about 20 m³/s of potable water, which is used for public supply. During the study period, aluminum coagulants: liquid aluminum sulfate (Al₂(SO₄)) or polyaluminium chloride (Al₂(OH)₅Cl) were used in WTP 1 and ferric chloride (FeCl₃) in WTP 2. In these WTPs, the sludge produced in the decantation stage was centrifuged with the help of Polyacrylamide polymers (anionic for WTP1 and cationic for WTP2) and, after adjusting the moisture content, it is sent for final disposal in licensed landfills.

2.2. Sample collection and preparation

Two sludge samples were collected, before and after the centrifugation process in WTP 1 and 2 (Fiore et al., 2020). The first sampling took place in October 2018 and the second in August 2019. Considering data from the historical series of rainfall in the city of São Paulo, collected at the National Institute at the meteorological stations close to the WTP studied (83856 and 83781), the samples were collected in periods of greater rainfall in 2018 and in the dry period of 2019. Considering these data, this study was carried out with sludge samples that represent the rainy and dry periods, respectively.

For the microbiological characterization of the sludge and identification of filamentous organisms, the collections were performed according to the Brazilian guidelines for sample collection and preservation (CETESB and ANA, 2011). On these same dates, centrifuged samples were also collected for the physicochemical characterization of the sludge, according to Method 1060 described in Standard Methods for the Examination of Water and Wastewater (APHA et al., 1998).

2.3. Identification of filamentous organisms

The identification of filamentous organisms was the identification of phytoplankton and protozooplankton communities, which was observed by an optical microscopy (Zeiss Microscope, Germany) with 400× magnification, in quintuplicate. Samples were analyzed within a maximum period of three hours, in order to ensure the vitality of the entire microbial community (CETESB and ANA, 2011). Specialized bibliographies for the identification of phytoplankton (Komárek and Foot 1983; Round et al., 1990; Hoek et al., 1995; Bicudo and Menezes, 2006) and protozooplankton organisms (Pennak, 1953; Lee et al., 1985; Foissner and Berger, 1996; Ruppert et al., 2005) were used.

2.4. Microbiological characterization

For the microbiological characterization of sludge, microbial density and morphology (Hermoso et al., 2006), Gram staining, and colorimetric alterations presumptive of the presence of total and thermotolerant coliforms were analyzed, besides the counting of colonies of enterobacteria suggestive of Escherichia coli (Morris et al., 1997; Meherdad et al., 2014; BD, 2014). To identify the presence of coliforms and E. coli, sludge samples were filtered by sterilized overlapping meshes with a minimum diameter of 0.7 mm to remove suspended solids with larger dimensions. For the centrifuged samples, preliminary procedures of resuspension, concentration, and filtration were performed. The centrifuged sludge samples were resuspended in sterile saline solution before filtration. The counting of colonies suggestive of E. coli was performed on diluted sludge samples (10⁻¹-10⁻⁶) in sterile saline solution (0.9% NaCl).

To determine the main microbial morphology of sludge samples, microscopic analyses were performed, in quintuplicate, at 1,000× magnification/oil immersion (Zeiss Microscope, Germany). A total of 10 fields were observed in each slide. To identify the presence of total coliforms and E. coli, chromogenic (ONPG)/fluorogenic (MUG) (Colilert®) substrates were used. Moreover, 0.1-ml aliquots of the suspensions were plated on MacConkey agar to quantify colonies suggestive of E. coli. After incubation under aerobic conditions for 24 hours, at a temperature of 37ºC, tests were read. These tests were performed in duplicate.

2.5. Physicochemical characterization

In Fiore et al. (2020), the analytical methods used to characterize the organic and inorganic parameters of the sludge samples and the physical-chemical data for the gross mass, leachate and solubilized extract are presented. The analyses were carried out by different laboratories accredited by the National Institute of Metrology, Standardization and Industrial Quality, in accordance with standards 10004, 1005 and 10006 of the Brazilian Association of Technical Standards (ABNT, 2004a; 2004b; 2004c). Average data on the sludge composition for each WTP were compared with the Brazilian reference values that classify solid waste in terms of risks to the environment and human health NBR 10.004 (ABNT, 2004a) and with studies with sludge containing aluminum and iron species.

3. RESULTS AND DISCUSSION

Tables 1 and 2 present the results of the characterization of algal and protozoan communities, respectively, in the non-centrifuged (NC) WTP sludge sample. For WTP Sludge 1 (NC/2018), the qualitative analysis showed five taxa for microalgae distributed in the classes Chlorophyceae (four) and Bacillariophyceae (one). For WTP Sludge 2 (NC/2019), the qualitative analysis showed three taxa of microalgae distributed in the classes Chlorophyceae (two) and Bacillariophyceae (one). Regarding protozoa, in WTP Sludge 1, we found taxa distributed in the phyla Alveolata and Amoebozoa, four taxa in October 2018 and two taxa in August 2019. In October 2018, the microscopic analyses of WTP Sludge 2 (before and after the centrifugation process) did not show representatives of the communities. In August 2019, we found two taxa of microalgae of the class Chlorophyceae and one taxon of the phylum Alveolata, protozoa group, in WTP Sludge 2.

Table 1.
Representatives of the microalgae group found in WTP sludges samples (non centrifuged samples).

WTP	Month	Division	Class	Genus
1	October 2018	Chlorophyta	Chlorophyceae	Pediastrumsp.
				Dictyosphaeriumsp.
				Desmodesmussp.
				Scenedesmussp.
		Heterokonthophyta	Bacillariophyceae	Aulacoseirasp.
	August 2019	Chlorophyta	Chlorophyceae	Pediastrumsp.
				Binucleariasp.
		Charophyta	Zygnematophyceae	Staurastrumsp.
2	August 2019	Chlorophyta	Chlorophyceae	Pediastrumsp.
				Microsporasp.

Table 2.
Representatives of the protozoa group found in WTP sludges samples (non centrifuged samples).

WTP	Month	Phylum	Subphylum	Genus
1	October 2018	Alveolata	Dinoflagellata	Glenodiniumsp.
				Ceratiumsp.
			Ciliophora	Euplotessp.
		Amoebozoa		Arcellasp.
	August 2019	Alveolata	Dinoflagellata	Ceratiumsp.
		Amoebozoa		Arcellasp.
2	August 2019	Alveolata	Dinoflagellata	Ceratiumsp.

The phytoplankton and zooplankton communities tend to respond to the limnological and climatic variables, such as pluviosity, winds, water temperature, nutrients concentration, water transparency, among others (Tundisi and Tundisi 2008; Esteves, 2011). In present study, the seasonal response of microalgae and protozoan groups could be related to changes in composition of WTP sludge. Low temperature in the dry season (August 2018) became an important factor reducing primary production and planktonic diversity (Zhao et al. 2019) which will lead to a change in the community structure (Pulsifer and Laws, 2021).

In the months analyzed, we found no microorganism of the microalgae and protozoan communities in the centrifuged WTP samples. According to Reali (1999), the centrifuge dewatering process has a principle of phase separation very similar to what occurs with gravity-settled particles, but with a force intensity hundreds or thousands of times greater than that of gravity. In this way, during centrifugation, microalgae and protozoa can be carried away with the water, not adhering to the flakes. Another possible cause may also be associated with the fact that centrifuged samples become dry and microorganisms may lose viability more quickly, making it impossible to identify them.

It should be noted that in WTP 1 and 2 studied, the sludge from the filter washing decanters is destined for reserve tanks. In these tanks the WTP sludge arrive with about 2 to 5% solids content. In these tanks, polymers are incorporated that will contribute to the sequential dewatering process, which is carried out using centrifuges. After dewatering, the solids content of the WTP sludge is raised to about 18 to 22%. At WTP 1, the WTP sludge still undergoes new drying processes inside the unit, before being sent to landfills. In WTP 2, after centrifugation, the WTP sludge are sent for final disposal.

Table 3 presents the results of the morphological characterization and Gram staining, as well as the quantification of total and thermotolerant coliforms (E. coli). In the 2018 WTP Sludge 1, microorganisms existed in all analyzed fields. In most of them, we found Gram-positive bacilli in both the non-centrifuged and centrifuged samples. In the 2019 sample, the density of microorganisms was low in both samples. By the Colilert™ test, we found total coliforms and E. coli in both 2018 samples, which was confirmed by the presence of colonies suggestive of E. coli. In the 2019 sample, we also found total coliforms and E. coli, but the counting of enterobacteria showed low density and no colonies suggestive of E. coli in both samples.

Table 3 shows that WTP Sludge 1 presented a high number of microorganisms in the period analyzed, higher than that of WTP Sludge 2. In the 2018 and 2019 WTP Sludge 2, the presence of microorganisms was lower in comparison with WTP Sludge 1. By the Colilert™ test, we found total coliforms and E. coli in the centrifuged sample and only total coliforms in the 2018 non-centrifuged sample. In the 2019 sample, we found total coliforms and E. coli in the non-centrifuged and centrifuged samples. The number of enterobacteria remained the same in the non-centrifuged sample, the density of enterobacteria was low, and the 2018 sample presented only one colony suggestive of E. coli. In the 2019 sample, the density of enterobacterial colonies was low and we observed a growth of colonies suggestive of E. coli only in the non-centrifuged sample.

The sludge analyzed in this study came from WTP decanters and is essentially constituted of dirt from raw water, coagulants, and polymers used in the dewatering stage. Thus, the origin of these microorganisms may be related to the composition of captured water, operational parameters, and environmental conditions (Schuroff et al., 2014; Souza and Ferreira, 2021; Roque et al., 2021; Bernegossi et al., 2022).

In Brazil, WTP sludges are solid waste and can be characterized in terms of risks to the environment and human health with the use of NBR 10.004 (ABNT, 2004a), which establishes pathogenicity as one of the factors that make waste hazardous. Considering our findings and, especially, that the referred standard only excludes from the pathogenicity classification sludge produced in sewage treatment plants, WTP Sludges 1 and 2 should be classified as hazardous waste, contrary to what is usually performed in Brazil, including the reference to the dangerousness of WTP sludges in the IBAMA Normative Instruction (IBAMA, 2012). However, considering that this is an exploratory study, the need for further research aimed specifically at microbiological characterizations of WTP sludge is suggested.

Table 3.
Presence of microorganisms in WTS SLUDGE 1 and 2 before and after centrifugation, collected in 2018 and 2019. (+) refers to presence and (-) to absence.

WTP	Microbiological indicator	2018		2019
		Non-centrifuged	Centrifuged	Non-centrifuged	Centrifuged
1	Presence of microorganisms in the fields analyzed	100%	100%	100%	96%
	Morphology and Gram staining	Low density in fields with a predominance of Gram-negative bacilli (90%), 8% Gram-positive cocci, and 2% Gram-positive bacilli.	Gram-negative bacilli in 98% of the fields and one spiryl in 2% of the fields.	Low density in 90% of the fields, with a predominance of Gram-negative bacilli, Gram-positive cocci, Gram-positive bacilli, and yeast.	Sparse distribution, with a predominance of Gram-negative bacilli, Gram-positive cocci, Gram-positive bacilli, and yeast.
	Total coliforms	+	+	+	+
	Thermotolerant coliforms (E. coli)	+	+	+	+
	Number of Enterobacteriaceae and colonies suggestive ofE. coli(CFU/ml)	4000 and 200	3200 and 500	Low density and 0
2	Presence of microorganisms	60%	80%	20%	80%
	Morphology and Gram staining	Sparse presence of Gram-negative bacilli, yeast, and Gram-positive cocci.		Low presence of Gram-negative bacilli.	Sparse presence of Gram-positive cocci, Gram-negative bacilli, and Gram-negative cocci
	Total coliforms	+	+	+	+
	Thermotolerant coliforms (E. coli)	-	+	+	+
	Number of Enterobacteriaceae and colonies suggestive ofE. coli(CFU/ml)	0	Low density and 1	Low density and 600	Low density and 0

Solid waste characterization is an essential activity to assess the existence of chemical and/or biological compounds, which pose risks to the environment and human health, and determines all activities for safe waste management. The identification of pathogenic organisms in the samples studied should guide the reuse of WTP sludges in their various applications, especially when the inhalation of particles containing pathogens is possible, which would represent a risk for individuals who work directly with sludge, such as workers, transporters, and sludge spreaders (Moreira et al., 2009; Alves and Marques, 2021). However, the exception of the Brazilian classification standard for sludge from sewage treatment plants should also be applied to WTP sludge, aiming to expand the potential for beneficial use of this material. Moreover, establishing specific methods for the identification of microorganisms in WTP sludge is necessary, as it already exists for sludge from sewage treatment plants in São Paulo. Table 4 presents the results of the leaching and solubilization analyses in the sludge samples from WTPs 1 and 2.

Table 4.
Results of the leaching and solubilization analyses of sludge from WTPs 1 and 2.

Sample analysis (mg/l)	Parameter	WTP SLUDGE 1		WTP SLUDGE 2		Reference value (NBR 10,004/2004)
		2018	2019	2018	2019
Solubilized	Barium	0.03	--	7.59	--	0.7
	Cadmium	--	--	--	--	0.005
	Lead	--	--	--	--	0.001
	Fluoride	--	--	1.1		1.5
	Aluminum	0.08	--	--	0.49	0.2
	Chloride	53.8	52.5	21.9	20.9	250
	Total iron	1.73	4.92	0.53	18.21	0.3
	Total manganese	10.75	1.94	0.94	0.22	0.10
	Sodium	3.18	9.99	1.96	19.38	200
Leached	Barium	--	0.36	7.72	0.47	70
	Cadmium	--	--	0.02	--	0.5
	Lead	--	--	0.16	--	1.0
	Fluoride	--	0.4	--	0.21	150

• (--) refers to concentrations below the detection limits.

Despite the lack of physicochemical characteristics that infer dangerousness to WTP sludge (flammability, corrosivity, reactivity, and toxicity), the analyses of the solubilized sludge samples from WTP s 1 and 2 showed high concentrations of iron and manganese, higher than the reference limits for inert residues. Thus, following the specifications of NBR 10.004 (ABNT, 2004a), sludge from WTPs 1 and 2 could be classified as Class II A waste, that is, non-hazardous and non-inert. The concentration of barium above the reference limit found in the solubilized 2018 WTP Sludge 2 also characterizes this waste as non-hazardous and non-inert, even if not recurrent in other previous samplings.

Some studies report that products containing these elements in their composition are added during the water treatment process, also considering their relationship with the composition of solids, since this is one of the main elements of soil formation (Roque et al., 2021; Ahmad et al., 2017; Ackah et al., 2018; Carneiro et al., 2013; Petris et al., 2019, Alves and Marques, 2021), which would justify the high concentration in the sludge samples analyzed.

The accumulation and release of manganese can represent an expensive and difficult problem to solve for WTPs. According to Moruzzi and Reali (2012), the presence of manganese in supply waters is associated with the presence of iron, in the soil or mineralized, usually in the form of manganese dioxide. Its soluble form usually appears in groundwater in the form of manganese bicarbonate and its insoluble form appears mineralized as insoluble carbonates, of which rhodochrosite (MnCO₃) and pyrolusite (MnO₂) are the most abundant.

Iron is an essential element for cellular metabolism. Xu et al. (2020) showed that the growth rate of bacteria such as E. coli can increase at high concentrations of iron. Thus, controlling the level of iron during the water treatment process is essential to reduce the concentration of potential pathogens, due to its harmful effects on the ecosystem and humans. In this study, we could not assess the correlation between a higher concentration of iron and presence of E. coli.

Manganese is harder to be removed from water, and the damage caused by its presence of manganese in water for human consumption is similar to that caused by the presence of iron, but on a larger scale. On the other hand, its purple color gives aesthetic limitations to the use of this water (Moruzzi and Reali, 2012). Grassi et al. (2020) showed that the presence of iron in the chemical composition of WTP sludge gives it a catalytic potential for the degradation of organic contaminants in wastewater.

4. CONCLUSION

According to the results, it was possible to identify algae, protozoa and bacteria in the WTP sludges studied, with greater diversity in the sludge produced at the station that used an aluminum-based coagulant. It was also possible to infer that the centrifugation process influences the increase in the concentration of microorganisms present in the WTP sludges.

In this exploratory research, cross-sectional sampling of the microbiological community was carried out, but due to its findings, it is recommended that further studies be carried out with representative samplings of the heterogeneity and seasonality of these residues. It is noteworthy that the disinfection of water in the WTPs studied occurs exclusively after the separation of the solid waste from the captured water; therefore, studies correlating the microbial community present in the raw water and in the generated sludge can contribute to the determination of the predictability of pathogenicity in WTP sludges.

Another important detail observed is that the studied WTP sludges should be classified as Class 1 waste according to the ABNT (2004a) standard, as they contain pathogens, contrary to the provisions of the current normative instruction in the country (IBAMA, 2012). These results point to the need for establishing safe procedures for the management of these residues and to reassess the Brazilian classification regulations regarding environmental risk and human health, since this excludes the risk associated with the pathogenicity of sludge from sewage treatment plants, but not for WTP sludges.

5. ACKNOWLEDGEMENTS

This work was supported by São Paulo Research Foundation - FAPESP (Proc.: 2018/00099-0).

REFERENCES

• ABNT. NBR 10.004. Resíduos sólidos - Classificação. Rio de Janeiro, 2004a. 71 p.
• ABNT. NBR 10.005. Lixiviação de resíduos - Procedimentos. Rio de Janeiro, 2004b. 71 p.
• ABNT. NBR 10.006. Procedimento para obtenção de extração solubilizada de resíduos sólidos. Rio de Janeiro, 2004c.
• ACHON, C. L.; BARROSO, M. M.; CORDEIRO, J. S. Leito de drenagem: sistema natural para redução de volume de lodo de estação de tratamento de água. Engenharia Sanitária e Ambiental, v. 13, p. 54-62, 2008. https://doi.org/10.1590/S1413-41522008000100008
  » https://doi.org/10.1590/S1413-41522008000100008
• ACHON, C. L.; BARROSO, M. M.; CORDEIRO, J. S. Resíduos de estações de tratamento de água e a ISO 24512: desafio do saneamento brasileiro. Engenharia Sanitária e Ambiental, v. 18, p. 115-122, 2013. https://doi.org/10.1590/S1413-41522013000200003
  » https://doi.org/10.1590/S1413-41522013000200003
• ACKAH, L.; GURU, R.; PEIRAVI, M.; MOHANTY, M.; MA, X.; KUMAR, S. et al Characterization of Southern Illinois water treatment residues for sustainable applications. Sustainability, v. 10, n. 5, p. 1374, 2018. https://doi.org/10.3390/su10051374
  » https://doi.org/10.3390/su10051374
• ACQUOLINI, G. T. Caracterização do lodo de estações de tratamento de água de Poroto Alegre/RS. 2017. 67 f. Dissertação (Mestrado em Ciência do Solo) -Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, Porto Alegre, 2017.
• AHMAD, T.; AHMAD, K.; ALAM, M. Sludge quantification at water treatment plant and its management scenario. Environmental Monitoring and Assessment, v. 189, p. 1-10, 2017. https://doi.org/10.1007/s10661-017-6166-1
  » https://doi.org/10.1007/s10661-017-6166-1
• ALVES, H. C.; MARQUES, G. L. O. Laboratory analysis of dehydrated sludge from water treatment stations in the metropolitan region of Belo Horizonte - MG for use in paving. Brazilian Journal of Development, v. 7, n. 2, p. 20793-20814, 2021. https://doi.org/10.34117/bjdv7n2-633
  » https://doi.org/10.34117/bjdv7n2-633
• APHA; AWWA; WEF. Standard Methods for the Examination of Water and Wastewater. 20. ed. Washington, 1998.
• BECTON DICKINSON GMBH. Manual BD. Instruções de utilização - meios em placas prontos a usar. Heidelberg, 2014.
• BERNEGOSSI, A. C.; FREITAS, B. L. S.; CASTRO, G. B.; MARQUES, J. P.; TRINDADE, L. F.; SILVA, M. R. L; et al A systematic review of the water treatment sludge toxicity to terrestrial and aquatic biota: state of the art and management challenges. Journal of Environmental Science and Health, Part A, v. 57, n. 4, p. 282-297, 2022. https://doi.org/10.1080/10934529.2022.2060021
  » https://doi.org/10.1080/10934529.2022.2060021
• BICUDO, C. E. M.; MENEZES, M. Gêneros de algas de águas continentais do Brasil: chave para identificação e descrições. São Carlos: RiMa, 2006.
• BORETTI, A.; ROSA, L. Reassessing the projections of the world water development report. NPJ Clean Water, v. 2, n. 1, p. 15, 2019. https://doi.org/10.1038/s41545-019-0039-9
  » https://doi.org/10.1038/s41545-019-0039-9
• BRASIL. Ministério da Saúde. Portaria GM/MS nº 888, de 04 de maio de 2021. Altera o Anexo XX da Portaria de Consolidação GM/MS nº 5, de 28 de setembro de 2017, para dispor sobre os procedimentos de controle e de vigilância da qualidade da água para consumo humano e seu padrão de potabilidade. Diário Oficial [da] União: seção 1, Brasília, DF, n. 85, p. 127, 07 de maio 2021.
• BRASIL. Presidência da República. Lei n. 12.305, de 05 de agosto de 2010. Institui a Política Nacional de Resíduos Sólidos; altera a Lei no 9.605, de 12 de fevereiro de 1998; e dá outras providências. Diário Oficial [da] União: seção 1, Brasília, DF, 03 ago. 2010.
• BRASIL. Secretaria Nacional de Saneamento. Plansab - Plano Nacional de Saneamento Básico. Brasília, 2019. 240 p.
• BRUNO, A.; SANDIONIGI, A.; RIZZI, E.; BERNASCONI, M.; VICARIO, S.; GALIMBERTI, A. et al Exploring the under-investigated “microbial dark matter” of drinking water treatment plants. Scientific reports, v. 7, n. 1, p. 1-7, 2017. https://doi.org/10.1038/srep44350
  » https://doi.org/10.1038/srep44350
• CARNEIRO, C.; WEBER, P. S.; ROSS, B. Z. L. Caracterização do Lodo de ETA gerado no Estado do Paraná. In: CARNEIRO, C.; ANDREOLI, C. V. (ed). Lodo de Estações de Tratamento de Água: Gestão e Perspectivas Tecnológicas. Curitiba: Sanepar, 2013. Cap. 3. p. 132-178.
• CETESB; ANA (Brasil). Guia nacional de coleta e preservação de amostras: água, sedimento, comunidades aquáticas e efluentes líquidas. São Paulo, 2011.
• DA SILVA, W. D.; BUSS, M. V.; DOS SANTOS, R. H.; PERAZZOLI, M. Monitoramento de uma leira de compostagem para tratamento de resíduos industriais orgânicos. In: SEMINÁRIO DE INICIAÇÃO CIENTÍFICA E SEMINÁRIO INTEGRADO DE ENSINO, PESQUISA E EXTENSÃO - SIEPE, 2017. Articles[…] Available at: https://periodicos.unoesc.edu.br/siepe/article/view/14657
  » https://periodicos.unoesc.edu.br/siepe/article/view/14657
• DI BERNARDO, L.; DANTAS, A. D. B.; VOLTAN, P. E. N. Métodos e técnicas de tratamento e disposição dos resíduos gerados em estações de tratamento de água. São Carlos: LDiBe, 2012. 540 p.
• ESTEVES, F. A. Fundamentos de Limnologia. São Paulo: Interciência, 2011.
• FIORE, F. A.; RODGHER, S.; ITO, C. Y. K.; BARDINI, V.S.S.; KLINSKY, L. M. G. Quality of surface water and generation of sludge at water treatment plants. Revista Ambiente & Água, v. 15, n. 5, 2020. https://doi.org/10.4136/ambi-água.256
  » https://doi.org/10.4136/ambi-água.256
• FOISSNER, W.; BERGER, H. A user-friendly guide to the ciliates (Protozoa, Ciliophora) commonly used by hydrobiologists as bioindicators in rivers, lakes, and waste waters, with notes on their ecology. Freshwater Biology, v. 35, p. 375-482, 1996. https://doi.org/10.1111/j.1365-2427.1996.tb01775
  » https://doi.org/10.1111/j.1365-2427.1996.tb01775
• GIGLIO, G. L.; SABOGAL-PAZ, L. P. Performance comparison of three methods for detection of Giardia spp. cysts and Cryptosporidium spp. oocysts in drinking-water treatment sludge. Environmental Monitoring and Assessment, v. 190, p. 1-10, 2018. https://doi.org/10.1007/s10661-018-7057-9
  » https://doi.org/10.1007/s10661-018-7057-9
• GRANDIN, S. R.; ALEM SOBRINHO, P.; GARCIA JR., A. D. Desidratação de Lodos Produzidos em Estações de Tratamento de Água. In: CONGRESSO BRASILEIRO DE ENGENHARIA SANITÁRIA E AMBIENTAL, 17., 1993, Natal. Anais[...] Natal: ABES, 1993. v. 2. p. 324-341.
• GRASSI, P.; DRUMM, F.C.; GEORGIN, J.; FRANCO, D.S.P.; FOLETTO, E.L.; DOTTO, G.L. et al Water treatment plant sludge as iron source to catalyze a heterogeneous photo-Fenton reaction. Environmental Technology & Innovation, v. 17, p. 100544, 2020. https://doi.org/10.1016/j.eti.2019.100544
  » https://doi.org/10.1016/j.eti.2019.100544
• HELLER, L.; PÁDUA, V. L. Abastecimento de água para consumo humano. 2. ed. Belo Horizonte: UFMG, 2010.
• HERMOSO, A. R.; FERREIRA, S.; SILVA, E. R.; MORAIS, J. L. Correlação entre a microfauna e parâmetros físico-químicos de um sistema de lodos ativados de uma indústria de refrigerantes. Brazilian Journal of Environmental Sciences, n. 4, p. 16-22, 2006.
• HOEK, C. V.; MANN, D. G.; JAHNS, H. M. Algae: an introduction to Phycology. Cambridge: University Press, 1995.
• HOWE, K.; HAND, D.; CRITTENDEN, J.; TRUSSELL, R.; TCHOBANOGLOUS, G. Princípios de tratamento de água. Cengace, 2017. 620 p.
• IBAMA. Instrução Normativa nº 13, de 18 de dezembro de 2012. Lista Brasileira de Resíduos Sólidos. Diário Oficial [da] União, Brasília, 20 dez. 2012.
• IBGE. Pesquisa Nacional de Saneamento Básico 2017: abastecimento de água e esgotamento sanitário. Rio de Janeiro, 2020.
• KOMAREK, J.; FOOT, B. Chlorophyceae (Grunalgen), Ordiniung: Chlrococcales. In: HUBER-PESTALOZZI, G. (ed.). Das Phytoplankton des Susswasers: systematik und biologie. Stuttgart: E. Schwiezerbat’sche Verlagsbuchhandlung, 1983. 1044p.
• KRISTANTI, R. A.; HADIBARATA, T.; SYAFRUDIN, M.; YILMAZ, M.; ABDULLAH, S. Microbiological contaminants in drinking water: Current status and challenges. Water, Air, & Soil Pollution, v. 233, n. 8, p. 299, 2022. https://doi.org/10.1007/s11270-022-05698-3
  » https://doi.org/10.1007/s11270-022-05698-3
• LEE, J. J.; HUTNER, S. H.; BOVEE, E. C. An illustrated guide to the Protozoa. Kansas: Society of Protozoologists, 1985. p. 629.
• MAKOVCOVA, J.; BABAK, V.; SLANY, M.; SLANA, I. Comparison of methods for the isolation of mycobacteria from water treatment plant sludge. Antonie van Leeuwenhoek, v. 107, p. 1165-1179, 2015. https://doi.org/10.1007/s10482-015-0408-4
  » https://doi.org/10.1007/s10482-015-0408-4
• MARQUES, D. M. L. M.; SILVA, A. P.; BIDONE, F. R. A. Avaliação da lixiviação de alumínio e da produção de ácidos graxos voláteis em reatores anaeróbios utilizados para estudar a disposição final de lodos de ETAs em aterros sanitários. In: CONGRESSO INTERAMERICANO DE ENGENHARIA SANITÁRIA E AMBIENTAL, 27., 2000, Porto Alegre. Anais[...] Rio de Janeiro: ABES, 2000. p. 3-8. 1 CD-ROM.
• MEHERDAD, F. et al Identification of bacterial population of activated sludge process and their potentials in pharmaceutical effluent treatment. British Biotechnology Journal, v. 4, n. 3, p. 317, 2014. https://doi.org/10.9734/BBJ/2014/7913
  » https://doi.org/10.9734/BBJ/2014/7913
• MOREIRA, R. C. A.; GUIMARÃES, E. M.; BOAVENTURA, G. R. A.; MOMESSO, A. M.; LIMA, G. L. Estudo geoquímico da disposição de lodo de estação de tratamento de água em área degradada. Química Nova, v. 32, n. 8, p. 2085-2093, 2009. http://dx.doi.org/10.1590/S0100-40422009000800019
  » http://dx.doi.org/10.1590/S0100-40422009000800019
• MORUZZI, R. B.; REALI, M. A. P. Oxidação e remoção de ferro e manganês em águas para fins de abastecimento público ou industrial: uma abordagem geral. Revista de Engenharia e Tecnologia, p. 29-43, 2012.
• MORRIS, R.; GRABOW, W. O. K.; JOFRE, J. Health-related water microbiology. Selected proceedings of the IAWQ 8th international symposium Mallorca, Spain, October 1996. Oceanographic Literature Review, v. 1, n. 45, p. 130, 1997.
• NAYERI, D.; MOUSAVI, S. A comprehensive review on the coagulant recovery and reuse from drinking water treatment sludge. Journal of environmental management, v. 319, p. 115649, 2022. https://doi.org/10.1016/j.jenvman.2022.115649
  » https://doi.org/10.1016/j.jenvman.2022.115649
• PENNAK, R.W. Freshwater Invertebrates. New York: Ronald Press, 1953.
• PETRIS, A.; GONÇALVES, M. J.; RORATTO, P. A.; GOULART, J. A. G. Physicochemical, microbiological and parasitological characterization of the filter backwash water from a water treatment plant of Blumenau-SC and alternatives for treatment and reuse. Revista Ambiente & Água, v. 14, 2019. https://doi.org/10.4136/ambi-agua.2372
  » https://doi.org/10.4136/ambi-agua.2372
• PULSIFER, J.; LAWS, E. Temperature Dependence of Freshwater Phytoplankton Growth Rates and Zooplankton Grazing Rates. Water, v. 13, n. 11, p. 1591, 2021. https://doi.org/10.3390/w1311159
  » https://doi.org/10.3390/w1311159
• RANKOVIĆ, B.; SAGATOVA, A.; VUJČIĆ, I.; MAŠIĆ, S.; VELJOVIĆ, Đ.; PAVIĆEVIĆ, V. et al Utilization of gamma and e-beam irradiation in the treatment of waste sludge from a drinking water treatment plant. Radiation Physics and Chemistry, v. 177, n. 109174, 2020. https://doi.org/10.1016/j.radphyschem.2020.109174
  » https://doi.org/10.1016/j.radphyschem.2020.109174
• REALI, M. A. P. (Org.). Noções gerais de tratamento e disposição final de lodos de estações de tratamento de água. Rio de Janeiro: ABES, 1999. 223 p. Projeto PROSAB.
• RICHTER, A. C. Tratamento de Lodos de Estações de Tratamento de Água. São Paulo: Edgard Blucher, 2001.
• RODGHER, S.; FIORE, F. A.; DOS SANTOS BARDINI, V. S.; FORMIGA, J. K. S.; KOGA-ITO, C. Y. et al Acute Toxicity of Leachates from Water Treatment Plants Sludge and Combinations with Soils from a Tropical Region. Water, Air, & Soil Pollution, v. 234, n. 2, p. 78, 2023. https://doi.org/10.1007/s11270-023-06080-7
  » https://doi.org/10.1007/s11270-023-06080-7
• ROQUE, A.; TEJEDA MONTALVAN, E.L.; GIMENEZ BOSCOV, M.E. Caracterização mineralógica, química e geotécnica do lodo da Estação de Tratamento de Água Taiaçupeba. Geotecnia, n. 151, p. 33-52, 2021. https://doi.org/10.24849/j.geot.2021.151.03
  » https://doi.org/10.24849/j.geot.2021.151.03
• ROUND, F. E.; CRAWFORD, R. M.; MANN, D. G. The Diatoms. Biology and Morphology of the Genera. Cambridge: University Press, 1990. 747 p.
• RUPPERT, E. E.; FOX, R. S.; BARNES, R. D. Zoologia dos Invertebrados: uma abordagem funcional - evolutiva. 7. ed. São Paulo: Roca, 2005. 1145 p.
• SCHUROFF, P. A.; BURGOS, N.; LIMA, N. R.; LOPES, A. M.; PELAYO, J. S. Caracterização fenotípica e genotípica de Escherichia coli, potencialmente patogênicas oriundas de estação de tratamento de água. Arquivos de Ciências da Saúde (FAMERP), v. 21, p. 93-98, 2014.
• SOUZA, C. D. R.; FERREIRA, I. B. P. Avaliação da eficiência de diferentes coagulantes utilizados em uma Estação de Tratamento de Águas. Research, Society and Development, v. 10, n. 13, p. e284101321127-e284101321127, 2021. https://doi.org/10.33448/rsd-v10i13.21127
  » https://doi.org/10.33448/rsd-v10i13.21127
• TUNDISI, J. G.; TUNDISI, T. M. Limnologia. São Paulo. Oficina de Textos, 2008.
• ULLMANN, I. F.; TUNSJO, H. S.; ANDREASSEN, M.; NIELSEN, K. M.; LUND, V.; CHARNOCK, C. Detection of aminoglycoside resistant bacteria in sludge samples from Norwegian drinking water treatment plants. Frontiers in microbiology, v. 10, n. 487, 2019. https://doi.org/10.3389/fmicb.2019.00487
  » https://doi.org/10.3389/fmicb.2019.00487
• WANG, C.; WEI, Z.; LIU, R.; BAI, L.; JIANG, H.; YUAN, N. The sequential dewatering and drying treatment enhanced the potential favorable effect of microbial communities in drinking water treatment residue for environmental recycling. Chemosphere, v. 262, n. 127930, 2021. https://doi.org/10.1016/j.chemosphere.2020.127930
  » https://doi.org/10.1016/j.chemosphere.2020.127930
• WHO. Guidelines for drinking-water quality: fourth edition incorporating the first addendum. Geneva: WHO, 2017.
• XU, H.; PEI, H.; JIN, Y.; MA, C.; WANG, Y.; SUN, J.; LI, H. High-throughput sequencing reveals microbial communities in drinking water treatment sludge from six geographically distributed plants, including potentially toxic cyanobacteria and pathogens. Science of the Total Environment, v. 1, n. 634, p. 769-779, 2018. https://dx.doi.org/10.1016/j.scitotenv.2018.04.008
  » https://dx.doi.org/10.1016/j.scitotenv.2018.04.008
• XU, L.; ZHOU, Z.; ZHU, L.; HAN, Y.; LIN, Z.; FENG, W. et al Antibiotic resistance genes and microcystins in a drinking water treatment plant. Environmental Pollution, v. 258, n. 113718, 2020. https://doi.org/10.1016/j.envpol.2019.113718
  » https://doi.org/10.1016/j.envpol.2019.113718
• ZHAO, Q. H.; WANG, J.; WANG, J. J.; WANG, J. X. L. Seasonal dependency of controlling factors on the phytoplankton production in Taihu Lake, China. Journal of Environmental Sciences, v. 76, p. 278-288, 2019. https://doi.org/10.1016/j.jes.2018.05.010
  » https://doi.org/10.1016/j.jes.2018.05.010

Publication Dates

• Publication in this collection
  23 Oct 2023
• Date of issue
  2023

History

• Received
  19 Apr 2023
• Accepted
  17 July 2023