Comparative Study of the Ecotoxicological and Histopathological Impacts of Effluent, Sludge Water, and Commonly Used Inorganic Fertilizers on Juvenile Oreochromis niloticus (Linnaeus, 1758)

Maria Aileen Leah G. Guzman, Emilyn Q. Espiritu*, Jewel Racquel Unson,
Vince Jethro Alba, Maria Larisse Hernandez, Lara Anne Sy,
Joan Ruby Dumo, and Jay Roy Espinas

Department of Environmental Science, School of Science and Engineering,
Ateneo de Manila University, Katipunan Ave. Loyola Heights, Quezon City, Philippines

*Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.




Wastewater treatment systems, designed to treat domestic wastes, produce effluents and sludge that are high in organic matter and nutrient content. These effluents and sludge are now being used as organic fertilizers because such nutrients and organic matter are vital to plant growth. However, without proper treatment, these substances may eventually find their way into bodies of water through run off and/or infiltration with potentially dangerous consequences. This study, therefore, investigated the potential toxic effects of effluents and sludge produced from wastewater treatment facilities against commonly used inorganic fertilizers to an aquatic species. Toxicity tests (expressed as mean 96-hr LC50 in mg/L) and histopathological examinations of the liver were conducted using juvenile Oreochromis niloticus (Linnaeus, 1758) exposed to varying concentrations of effluent, sludge, and inorganic fertilizers (i.e., urea and complete fertilizer) to assess both acute and sublethal effects. The results of the acute toxicity tests show concentrations (expressed as mean 96-hr LC50 in mg/L or ppm) arranged in decreasing order of toxicity to tilapia: complete fertilizer 14-14-14 (1,396 ppm) > urea (16,152 ppm) > sludge (145,900 ppm) > effluent (465,000 ppm). Histopathological examinations of liver tissues showed that exposure to the two inorganic fertilizers resulted to blood congestion and degeneration in comparison to those exposed to the sludge. Furthermore, results for fishes exposed to the lowest concentrations of the effluent also showed alterations in the liver tissue. These results demonstrate that the sludge and effluent are less toxic by several orders of magnitude than the inorganic fertilizers. It is suggested that further chronic toxicity and histopathological studies be done to determine their long-term impacts to receiving aquatic organisms to establish their potential for agricultural applications.



Waste management continues to be one of the environmental challenges that many countries face today. Wastes from households, industries, and agricultural runoff are discharged into bodies of water resulting in a significant level of pollution that cause potential risks to human health and the environment (World Bank 2003). In response, domestic wastewater treatment systems (DWWTS) have been devised to lessen the impact of domestic wastewater on the environment while at the same time allowing for the byproducts, effluent, and sludge to be utilized by humans (Boer & Blaga 2016). . . . . read more



[ADB] Asian Development Bank. 2016. A guide to sanitation safety planning in the Philippines: Step-by-step risk management for safety reuse and disposal of wastewater, greywater and excreta. Mandaluyong City (Philippines): ADB.
AL-NAKSHABANDI G, SAQQAR M, SHATANAWI M, FAYYAD M, AL-HORANI H. 1997. Some environmental problems associated with the use of treated wastewater for irrigation in Jordan. Agricultural Water Management 34(1): 81–94.
AKIN E, AL-SALEM S, CAIRNCROSS A, SCHWARTZBROD J, SHUVAL HI, SINGH CN, YANEZ F. 1989. Health guidelines for the use of wastewater in agriculture and aquaculture. Geneva (Switzerland): World Health Organization.
ASUQUO IE, ESSIENIBOK MA. 2014. Acute Toxicity of NPK 15:15:15 Fertilizer on the fingerlings of Heterobranchus bidorsalis. West African Journal of Applied Ecology 22(2): 31–44.
BOER J, BLAGA P. 2016. Optimizing production costs by redesigning the   treatment process of the Industrial waste water. Procedia Technology 22: 419–424.
CAMARGO MMP, MARTÍNEZ CBR. 2006. Biochemical and physiological biomarkers in Prochilodus lineatus submitted to in situ tests in an urban stream in southern Brazil. Environmental Toxicology and Pharmacology 21: 61–69.
CENGIZ EI. 2006. Gill and kidney histopathology in the freshwater fish Cyprinus carpio after acute exposure to deltamethrin. Environmental Toxicology and Pharmacology 22(2): 200–204.
CHANNA A, MIR IH. 2009. Distribution of neutral lipids in the intestinal tract and liver of Schizothorax curvifrons Heckel: A histochemical study. Indian J. Applied Pure Biol. 24: 285–288.
CLARK BO, SMITH SR. 2010. Review of ‘emerging’ organic contaminants in biosolids and assessment of international research priorities for the agricultural use of biosolids. Environment International 37(1): 226–247.
CLARKSON DT, HOPPER MJ, JONES LHP. 1986. The effect of root temperature on the uptake of nitrogen and the relative size of the root system in Lolium perenne. I. Solutions containing both NH4– and NO3–. Plant, Cell and Environment 9(7): 535–545.
CAPKIN E, KAYIS S, BORAN H, ALTINOK I. 2010. Acute toxicity of some agriculture fertilizers to Rainbow Trout. Turkish Journal of Fisheries and Aquatic Sciences 10: 19–25.
[DPWH] Department of Public Works and Highways. 2013. Support for the Nationwide Roll-out of the National Sewerage and Septage Management Program. Manila (Philippines): Department of Public Works and Highways. 11p.
[EPA] Environmental Protection Agency. 2004. Primer for Municipal Wastewater Treatment Systems. Washington, DC: US EPA.
[EPA] Environmental Protection Agency. 2015. Agriculture: Nutrient Management and Fertilizer. Retrieved from
ESPIRITU E, TERAN A, ANTONIO R. 2001. Development of standard toxicity tests for tropical aquatic environments: 1. The use of Tilapia, Oreochromis niloticus (L.), as toxicity test organism for freshwater habitats. Philippine Scientist 48: 17–34.
FIGUEIREDO-FERNANDES A, FERREIRA-CARDOSO JV, GARCIA-SANTOS S, MONTEIRO SM, CARROLA J, MATOS P, FONTAÍNHAS-FERNANDES A. 2007. Histopathological changes in liver and gill epithelium of Nile tilapia, Oreochromis niloticus, exposed to waterborne copper. Pesquisa Veterinária Brasileira, 27(3): 103–109.
[FPA] Fertilizer and Pesticide Authority. 2015. Fertilizer Regulation Division. Quezon City (Philippines): Department of Agriculture. Retrieved from
HAMILTON M, RUSSO R, THURSTON R. 1977. Trimmed Spearman-Karber Method for estimating median lethal concentrations in toxicity bioassays. Washington, DC: US Environmental Protection Agency.
KIVAISI AK. 2001. The potential for constructed wetlands for wastewater treatment and reuse in developing countries: A review. Ecological Engineering 16(4): 545–560.
KUMAZAWA K. 1997. Use of sewage sludge for agriculture in Japan (IAEA-TECDOC-971). Vienna (Austria): International Atomic Energy Agency.
LAITH A, AMBAK MA, HASSAN M, SHERIFF SM, NADIRAH M, DRAMAN AS, NAJIAH M. 2017. Molecular identification and histopathological study of natural Streptococcus agalactiae infection in hybrid tilapia (Oreochromis niloticus). Veterinary World 10(1): 101–111.
MARA D. 2004. Domestic wastewater treatment in developing countries. London (UK): Earthscan Publication Ltd.
MARGUÍ E, IGLESIAS M, CAMPS F, SALA L, HIDALGO M. 2015. Long-term use of biosolids as organic fertilizers in agricultural soils: potentially toxic elements occurrence and mobility. Environmental Science and Pollution Research 25(5): 4454–64.
MOHAPATRA DP, CLEDÓN M, BRAR SK, SURAMPALLI RY. 2016. Application of wastewater and biosolids in soil: Occurrence and fate of emerging contaminants. Water, Air & Soil Pollution 227: 77.
ORON G, CAMPOS C, GILLERMAN L, SALGOT M. 1999. Wastewater treatment, renovation and reuse for agricultural irrigation in small communities. Agricultural Water Management 38(3): 223–234.
RIGBY M, MONTZKA SA, PRINN RG, WHITE JWC, YOUNG D, O’DOHERTY S, LUNT MF, GANESAN AL, MANNING AJ, SIMMONDS PG, SALAMEH PK, HARTH CM, MUHLE J, WEISS RF, FRASER PJ, STEELE LP, KRUMMEL PB, MCCULLOCH A, PARK S. 2017. Role of atmospheric oxidation in recent methane growth. Proceedings of the National Academy of Sciences of the United States. Retrieved from on 10 Dec 2018.
SAHA S, SAHA B, PATI S, PAL B, HAZRA GC. 2017. Agricultural use of sewage sludge in India: Benefits and potential risk of heavy metals contamination and possible remediation options – A review. International Journal of Environmental Technology and Management 20(3/4): 183–199.
SOUFY H, SOLIMAN MK, EL-MANAKHLY EM, GAAFAR AY. 2007. Some biochemical and pathological investigations on monosex Tilapia following chronic exposure to carbofuran pesticides. Global Veterinaria 1: 45–52.
TOZE S. 2006. Reuse of effluent water – Benefits and risks. Agricultural Water Management 80: 147–159.
UHUO C, NWELE D, ODIKAMNORO O, IBIAM G, AZI S. 2013. The toxicity effect of N.P.K. Agro-fertilizer on Oreochromis niloticus fingerlings, the physiological impact. Journal of Biology, Agriculture and Healthcare 3(9): 5–8.  
VELKOVA-JORDANOSKA L, KOSTOSKI G. 2005. Histopathological analysis of liver in fish (Barbus neridionalis Petenyi Heckel) in reservoir Trebenista. Nat. Croat.14(2): 147–153.
VELMURUGAN B, SELVANAYAGAM M, CENGIZ EI, UNLU E. 2009. Histopathological changes in the gill and liver tissues of freshwater fish, Cirrhinus mrigala exposed to dichlorvos. Brazilian Archives of Biology and Technology 52(5): 1291–96.
WORLD BANK. 2003. Philippines – Environment Monitor 2003. Washington, DC (USA).
WORLD BANK. 2007. Philippines – Environmental Monitor 2006. Washington, DC: (USA).