Biotechnology involves the provision of services to society by microbial communities. By using microorganisms to detoxify contaminated water, and environmentally friendly solutions to the treatment of wastewater. Isolates of fungi Aspergillus niger, Candida albicans and microalgal isolates Tetradesmus nygaardi and Scenedesmus quadricauda were efficiently utilized to treat wastewater. The wastewater sample was taken from Erbil wastewater channel near Dhahibah village, the sample was analyzed for physicochemical parameters such as pH, EC, TDS, BOD5, PO4, NH4, NO3, and NO2 (every three day) during 21 days of experiment. Results revealed that a mixed culture of S. quadricauda with T. nygaardi were shows the best removal of PO4, NH4, NO3 and NO2 which was 94.94%, 90.73%, 88.23%, 93.84% respectively. Whereas a mixed culture of T. nygaardi with A. niger showed the best removal of BOD5 (94.9%), the highest reduction in electrical conductivity and total dissolved solid were recorded by mix culture of A. niger with C albicans which was 81.65% and 81.52%. During the treatment period chlorophyll-a concentration reached the highest value of (1.052, 1.005 and 2.521 mg. l-1). Statistically, there were a significant difference (p≤0.05) between the control and all microbial strains for all wastewater tested variables.

The nutrients Phosphorous, Nitrogen and Carbon are essential for aquatic life. However, in excess they also cause serious problems. For this reason, wastewater treatment must meet nutrient effluent limits. A wastewater sample was taken near Dhahibah village from the Erbil wastewater channel in the north of Iraq. In this experiment, pure cultures of Aspergillus niger and Candida albicans were used to treat wastewater. Samples were measured for physicochemical parameters like EC, pH, Phosphate, Nitrate, Nitrite, and BOD5 using standard methods every third day during 21 days of experiment. The results revealed that Aspergillus niger had the maximum efficiency in removing BOD5, NH4, NO3, and EC (87.27, 89.57, 83.52, and 78.49%) respectively. On the other hand, during the experimental period, Candida albicans had the maximum efficiency in decreasing PO4, and NO2, were (91.58% and 88.89%), respectively. Statistically, there were differences (P≤0.05) between the control sample and the treated wastewater sample for both fungal stains for all parameters during the experiment.

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Microalgae have been increasingly used for wastewater treatment due to their capacity to assimilate nutrients. Samples of wastewater were taken from the Erbil wastewater channel near Dhahibha village in northern Iraq. The microalga Coelastrella sp. was used in three doses (0.2, 1, and 2g. l-1) in this experiment for 21 days, samples were periodically (every 3 days) analyzed for physicochemical parameters such as pH, EC, Phosphate, Nitrate, and BOD5, in addition to, Chlorophyll a concentration. Results showed that the highest dose 2g.l-1 was the most effective dose for removing nutrients, confirmed by significant differences (p≤0.05) between all doses. The highest removal percentage was recorded for ammonium pass 96% followed by NO3 with 95%, while BOD5 ranged from 88.7 to 93.5%. Decreases in nutrients coincided with an increase in chlorophyll-a content with the highest biomass on the 17th day of the experiment reaching 1.43 mg. l-1.