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Sustainable development is based on environmental, social, economic, and technical dimensions. In this study, the sustainability of wastewater treatment techniques in urban areas of Iraq was assessed using a multi-criteria decision analysis (MCDA)/the weighted sum model (WSM). The analysis was performed on 13 operating wastewater treatment plants in 10 provinces, Iraq using a questionnaire sheet with the assistance of 52 specialists in the Ministry of Municipalities and Public Works, Iraq. Four types of wastewater treatment techniques (Conventional Treatment, Oxidation Ditches, Aeration Lagoons, and membrane bio-reactor (MBR)) were assessed. The environmental, social, economic, and technical dimensions were represented by 11, 5, 7, and 4 indicators, respectively. The main results of this study indicate that the sustainability of MBR recorded the highest total importance; the order of the total importance from the highest to the lowest was: MBR > Oxidation Ditches > Aeration Lagoons > Conventional Treatment. The environmental dimension proved its dominance in the four studied treatment techniques' sustainability as it recorded the maximum contribution to sustainability. While the technical dimension recorded the least contribution to sustainability, the order from the highest to the lowest was: Environmental Dimension > Economic Dimension > Social Dimension > Technical Dimension.

An investigation into two non-toxic natural coagulants abundantly growing in different countries, cactus (Opuntia spp.) and okra was performed on monthly river water samples (one-year period). The studied case was the Euphrates river/Al-Mashroo canal/Iraq. Six statistical models were interpreted and tested describing the residual turbidity after Coagulation-Flocculation for the three studied cases (Optimum-Coagulant-Dose, Optimum-Flocculator-Velocity-Gradient and Optimum-Flocculation-Time). According to the environmental parameters recorded during the study and the statistical analyses, two facts were concluded. The first fact was that controlling the Optimum-Flocculator-Velocity-Gradient of the Coagulation-Flocculation process gave the highest contribution ratio of the models. The second fact was that the most significant environmental parameter (statistically) in the Coagulation-Flocculation process was the initial turbidity. This was proved for the two natural coagulants under study. Also, from the results of the study, it was concluded that the two natural coagulants were of similar coagulation-flocculation properties, and they were competent for turbidity removal.

Autoregressive Integrated Moving Average (ARIMA) Box-Jenkins models combine the autoregressive and moving average models to a stationary time series after the appropriate transformation, while the nonlinear autoregressive (N.A.R.) or the autoregressive neural network (ARNN) models are of the kind of multi-layer perceptron (M.L.P.), which compose an input layer, hidden layer and an output layer. Monthly streamflow at the downstream of the Euphrates River (Hindiya Barrage) /Iraq for the period January 2000 to December 2019 was modeled utilizing ARIMA and N.A.R. time series models. The predicted Box-Jenkins model was ARIMA (1,1,0) (0,1,1), while the predicted artificial neural network (N.A.R.) model was (M.L.P. 1-3-1). The results of the study indicate that the traditional Box-Jenkins model was more accurate than the N.A.R. model in modeling the monthly streamflow of the studied case. Performing a one-step-ahead forecast during the year 2019, the forecast accuracy between the forecasted and recorded monthly streamflow for both models was as follows: the Box-Jenkins model gave root mean squared error (RMSE = 48.7) and the coefficient of determination R2 = 0.801), while the (NAR) model gave (RMSE = 93.4) and R2 = 0.269). Future projection of the monthly stream flow through the year 2025, utilizing the Box-Jenkins model, indicated the existence of long-term periodicity.

This paper presents an experimental work conducted to study the properties of concrete incorporating (0-100) % of local (in Iraq) crushed limestone (CLS) as a partial replacement of coarse aggregate. Supplementary Cementitious Materials (SCM) such as High Reactivity Metacaoline (HRM) and Rice Husk Ash (RHA) were added to the mixtures to improve the properties of fresh and hardened concrete. The selective mixtures in this study were arranged into three groups, the first without (SCM), the second with (RHA), and the third with (HRM). Each of them (being with different ratios of (CLS) as a coarse aggregate) was tested for comparison with the reference mixtures. The slump and air contents were evaluated for the fresh concrete. The absorption as well as compressive strength (CS) and flexural strength (FS) were evaluated for the hardened specimens after 7 and 28 days. According to the results, the concrete with CLS as a coarse aggregate gained less performance than the ordinary concrete but the (SCM) improved the properties of the concrete mixtures. The results show that the HRM was more effective than the RHA with respect to the mechanical properties.