Wpływ zrzucanych ścieków przemysłowych na parametry wód powierzchniowych na obszarze miejskim Onitsha w południowowschodniej Nigerii

Chemical industries in Onitsha urban area of southeastern Nigeria have been discharging large quantities of effluents into surface streams. These streams are the primary sources of water used by poor households for domestic purposes. This study examines the effects of effluents on the physicochemical and microbiological characteristics of the recipient streams. This objective was achieved by collecting eight effluents and twenty-two water samples from control points, discharge locations and exit chutes of the effluents for analysis. The results of the study characterised the effluents and their effects on the recipient streams. The effluents cause gross pollution of the streams as most of the parameters including pH, total dissolved solids (TDS), turbidity, biological oxygen demand (BOD), chemical oxygen demand (COD), Mg, NO3, Fe, Cu, Pb, Cr, total heterotrophic count (THC) and total coliform group (TCG) returned high values that exceeded the World Health Organisation’s (WHO) benchmark from 2011 for drinking water quality. Only dissolved oxygen (DO), Na, Zn, Ca, and Na returned values lower than the WHO guideline. E. coli was found in all the samples; TCG was also high. This paper, therefore, recommends that the effluent generating industries should treat their effluents before disposal.Przemysł chemiczny na obszarze miejskim Onitsha w południowowschodniej Nigerii odprowadza duże ilości ścieków do strumieni. Strumienie te są podstawowym źródłem wody dla ubogich gospodarstw domowych. W pracy analizowano wpływ ścieków przemysłowych na fizyczne, chemiczne i mikrobiologiczne właściwości wody w strumieniach. Cel ten osiągnięto, pobierając próby wody do analiz z 8 odpływów, z 22 punktów kontrolnych i miejsc zrzutu. Wyniki charakteryzują odpływy i ich wpływ na wody odbiornika ścieków. Zrzuty ścieków powodowały znaczne zanieczyszczenie strumieni, ponieważ większość parametrów (pH, zawiesiny, mętność, BZT, ChZT, Mg, NO3, Fe, Cu, Pb, Cr, suma bakterii heterotroficznych, bakterie grupy coli) przekraczała normy jakości wody pitnej ustalone przez WHO w 2011 r. Jedynie stężenie rozpuszczonego tlenu, Na, Zn, Ca i Na spełniały te normy. Obecność E. coli stwierdzano we wszystkich próbkach, duże były także wartości stężenia bakterii grupy coli. Zaleca się, aby zakłady przemysłowe poddawały ścieki oczyszczaniu przed ich zrzutem do strumieni

Health implications of stream water contamination by industrial effluents in the Onitsha urban area of Southeastern Nigeria

Nigeria has abundant surface and ground water resources many of which are polluted and can be detrimental to human health when consumed. This study investigated the effects of effluents discharged by industries into streams on the health of people who depend on stream water for domestic purposes in the Onitsha urban area of eastern Nigeria. Water samples collected from eleven discharge locations underwent physico-chemical and microbiological analyses. Data on the effects of industrial effluents on health were obtained from records in the public hospitals located in Onitsha as well as through questionnaire surveys and field observations. The results of the analyses revealed that the effluents grossly degrade surface water bodies; several parameters (temperature, iron, dissolved oxygen, turbidity, biological oxygen demand, chemical oxygen demand, lead, magnesium, total heterotrophic counts, total coliform group, pH) had values which were higher than the WHO (2011) safety limits for drinking water. The contamination of investigated streams by effluents had negative impact on the health of stream users. The discussion included health effects of polluted water and the prevalence of water borne or related diseases in the area. Implications of these findings were also discussed. Management measures capable of minimizing contamination of surface water in the study area were suggested