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Physico-Chemical and Biological Characteristics of the Oum Er Rbia Estuary (North Atlantic Moroccan Coast) – Impact of Urban Wastewater

Bengriche Rachida, Bouchafra El Mostafa, Chaouite Jamila, Nafia Mohammed, Moncef Mohammed

Journal of Ecological Engineering

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2024

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Vol. 25, nr 1

1--16

EN

This study aimed to monitor abiotic factors at three stations in the Oum Er Rbia estuary, not far from the mouth. The stations were situated upstream (S1), in front (S2) and downstream (S3) from the discharge of urban wastewater from the town of Azemmour, which is discharged directly without treatment near the estuary mouth. The selection of these stations appeared appropriate to assessing the quality of the waters, which are influenced by both marine hydrodynamics resulting from very low freshwater inflows and sewage discharges. Monitoring of several parameters, including temperature, pH, dissolved oxygen, conductivity, salinity, turbidity, as well as the content of chlorophyll α and pheopigments, enabled the examination of the impact of marine hydrodynamics and the and the specific characteristics of the three surveyed stations. The analyses were performed using R software version 4.2.0. The results obtained indicate that the studied physico-chemical and biological parameters exhibited variations with significant correlations. Statistical approaches allowed the determination of profiles for stations S1, S2 and S3. It is evident that S1 (located slightly far from the discharge) showed a profile that tended to differ from the other two stations, S2 and S3, especially for certain parameters (temperature, pH, turbidity, and chlorophyll a). On the other hand, all stations were impacted to some extent by the discharge of wastewater during rising tides. The present study can serve as an assessment tool to support decision-making regarding the physico-chemical quality of the waters of the Oum Er Rbia estuary.

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Physical-chemical characterisation of the urban wastewater - case study of the Boumerdes region, North - Algeria

Ait Baziz Djalal, Maazouzi Abdelhak, Lachache Salih

Journal of Water and Land Development

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2022

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no. 54

243--250

EN

The objective of this study is to assess the physical-chemical quality of urban wastewater from the city of Boumerdès, in northern Algeria with regard to the threshold values for irrigation or their discharge in aquatic ecosystems. Five sampling points were carried out of the study area in April 2017. The results obtained of physical-chemical parameters indicating pollution show that the water course is exposed to pollution mainly of organic origin. It’s expressed by a high maximum value according to Algerian and World Health Organisation standards: chemical oxygen demand (COD 886 mg O2∙dm-3), biochemical oxygen demand (BOD5 490 mg O2∙dm-3), nitrate (NO3- 73.09 mg∙dm-3), nitrite (NO2- 6 mg∙dm-3), ammonium (NH4+ 23 mg∙dm-3) and phosphates (PO43- 7.3 mg∙dm-3). The COD to BOD5 rate of 1.8, show that the effluents must be treated before being discharged into the receiving environment. However, it is lower than 2, which makes them easily biodegradable and can be treated by a biological system such as a natural lagoon. It shows also a diversified origin of the pollution. It is predominantly domestic origin, it could have an adverse effect on public health, presenting a risk of environmental eutrophication, contamination of soil and water resources. The physical-chemical characterisation of the urban wastewater shows that they are quite loaded and prezent a pollution in nitrogenous compounds, a treatment is requested before the direct discharge to the receiving environment or their reuse in the irrigation.

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Rozkład związków organicznych pochodzenia antropogenicznego w retentatach po ultrafiltracji i odwróconej osmozie w dwustopniowym procesie ozonolizy i fotolitycznego utleniania

Kowalska Katarzyna, Felis Ewa, Dudziak Mariusz, Garbaczewski Leon

Przemysł Chemiczny

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2020

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T. 99, nr 10

1495--1500

PL

Badano podatność na rozkład związków organicznych (w tym związków fenolowych) obecnych w retentatach uzyskanych po ultrafiltracji i odwróconej osmozie oczyszczonych ścieków miejskich, stosując dwustopniowy proces ozonolizy i fotolitycznego utleniania. Wykazano, że podczas ozonolizy i fotolizy związki te zostają usunięte, przy czym stopień usunięcia zależał od czasu ekspozycji matrycy na czynnik utleniający. Skojarzenie ozonolizy i fotolizy umożliwiło zwiększenie efektywności usuwania badanych zanieczyszczeń, przy czym niektóre z nich (np. związki fenolowe) były usuwane w zadowalającym stopniu już w procesie jednostopniowym, po ozonolizie.

EN

Real retentates from the treated wastewater were studied for content of total, org. and inorg. C, total N, PhOH index and absorbance at 254 nm. Samples were taken after 30 min exposure to O₃ and after 15, 30, 60, and 120 min long irrdn. with UV. A decrease in total C content, PhOH index and absorbance was obsd. The combination of ozonolysis and photolysis resulted in increasing the effectiveness of wastewater treatment.

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Manual Treatment of Urban Wastewater by Chemical Precipitation for Production of Hydroponic Nutrient Solutions

Correia Tânia, Regato Mariana, Almeida Adelaide, Santos Teresa, Amaral Leonor, Carvalho Fátima

Journal of Ecological Engineering

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2020

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Vol. 21, nr 3

143--152

EN

An urban wastewater treatment system was developed in Portugal for posterior in situ feasibility testing at the Bulgarian Antarctic Base, using its domestic wastewater. The aim of this system was to develop a low cost, integrated approach for wastewater treatment and production of nutrient solutions (NS) for hydroponic cultivation of lettuce (Lactuca sativa var. crispa) in Antarctic stations, or any other place where the lack of resources and logistical hardships make the wastewater treatment and reuse impractical. The wastewater treatment system consisted in manual agitation lime chemical precipitation (LCPm) and effluent natural neutralization (NN) by atmospheric CO2 carbonation reactions (with and without air injection). The resulting effluent/NS had macronutrient values (nitrogen and phosphorous) for the hydroponic cultivation of lettuce below the values of commercial NS and a high pH (pH ≈ 8). The treatment achieved a total coliform removal rate of 100%. Before the LCPm treatment system development, several lime-based reagents were tested under different reaction pH and using mechanical agitation, to access their organic matter removal efficiency, as chemical oxygen demand (COD). The best COD removal results obtained were: commercial Ca(OH)2 (pH 11.5 – 89%), reagent grade Ca(OH)2 (pH 11.5 – 79%) and CaO (pH 12.0 – 64%).

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Occurence of Metals in Total Suspended Solids in Urban Waters Determined by Sequential Extraction

Drozdova J., Raclavska H., Skrobankova H.

Inżynieria Mineralna

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2014

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R. 15, nr 2

35--39

EN

The binding of metals to total suspended solids (TSS) and their speciation in urban wastewater drastically influences the efficiency of capturing metals in sewage sludge in the framework of wastewater treatment plant technology. In this article, a modified sequential extraction procedure of the Bureau Communautaire de reference (BCR) was applied to TSS from urban wastewater and digested sludge samples. Samples were collected from combined sewer system and the Central Wastewater Treatment Plant in Ostrava, Czech Republic. The collection of wastewater samples and digested sludge was performed April to June 2013. Altogether, 42 samples of urban wastewater and 3 samples of digested sludge were obtained. The sequential extraction of TSS has proven that the highest proportions of As, Cr, Cu, Ni and Fe are associated with the residual fraction (61-75%). Zn and Mn are bound to the reducible fraction (64-65%). Finally, Pb and Cd are bound predominantly to the oxidizable fraction (56%). The results show that general trend proportions of metals from TSS in the oxidizable fraction is Cd ~ Pb > Cu > Zn > Fe > Ni > Cr > As > Mn. The distribution of metals between fractions was highly variable in digested sludge. The smallest amounts of all metals in digested sludge are associated with the exchangeable fraction (Ni 5.8%; other metals < 3.7%). Cadmium, Zn and Mn are predominantly bound within the reducible fraction (68%, 37% and 35%). In the case of the oxidizable fraction, the contents of all metals are relatively low (max 20.3% of Fe). Except Cd, the predominant portions of all metals in digested sludge are bound to residual fraction (45.8-99.7%). The comparison of distribution metals in the individual fractions from TSS and digested sludge shows that the portions of Cd, Cu, Cr, Mn, Pb, Zn and Fe are significantly different. The results indicated that Cu, Cd, Pb, Zn and Mn in digested sludge are bound in silicates well as to the phosphates.

PL

Wiązanie metali we frakcji ciał stałych zawieszonych w wodzie (TSS – Total Suspended Solids) oraz ich specjacji w miejskich ściekach drastycznie wpływa na efektywność wychwytywania metali w osadach ściekowych w ramach technologii oczyszczalni ścieków. W tym artykule, zmodyfikowana procedura ekstrakcji sekwencyjnej biura Bureau Communautaire de Reference (BCR) została zastosowana do zawiesiny ciał stałych ze ścieków komunalnych i przefermentowanych próbek osadu. Próbki pobrano z połączonego systemu kanalizacji i Centralnej Oczyszczalni Ścieków w Ostrawie, Czechy. Pobieranie próbek ścieków i przefermentowanego osadu przeprowadzano od kwietnia do czerwca 2013 roku. Łącznie uzyskano 42 próbki ścieków komunalnych oraz 3 próbki przefermentowanego osadu. Sekwencyjna ekstrakcja TSS dowiodła, że największy odsetek As, Cr, Cu, Ni i Fe jest związany we frakcji pozostałości (61-75%). Zn i Mn są związane we frakcji redukowalnej (64-65%). Wreszcie, Pb i Cd są związane głównie we frakcji utlenialnej (56%). Wyniki pokazują, że ogólny trendu proporcji metali pochodzących z TSS we frakcji utlenialnej przedstawia się następująco: Cd ~ Pb> Cu> Zn> Fe> Ni> Cr> W> Mn. Rozkład metali między frakcjami różnił się znacząco w przefermentowanym osadzie. Najmniejsze ilości wszystkich metali w przefermentowanym osadzie związane są z frakcją wymienną (Ni 5,8%; inne metale <3,7%). Kadm, Zn i Mn są głównie związane we frakcji redukowalnej (68%, 37% i 35%). W przypadku frakcji utlenialnej, zawartość wszystkich metali jest stosunkowo niska (maksymalnie 20,3% Fe). Z wyjątkiem Cd, dominujące porcje wszystkich metali w przefermentowanego osadu są związane z frakcji pozostałości (45.8-99.7%). Porównanie dystrybucji metali w poszczególnych frakcjach z TSS i przefermentowanego osadu wskazuje, że części Cd, Cu, Cr, Mn, Pb, Zn i Fe są znacząco różne. Wyniki wskazują, że Cu, Cd, Pb, Zn i Mn z przefermentowanego osadu związane są z krzemianami a także fosforanami.