This study presents the hydrochemical composition of groundwater under long-term irrigation of Wonji plain (Ethiopia) and its quality status for drinking purpose. Groundwater samples were collected from 30 groundwater monitoring tube wells installed at different parts of the sugarcane plantation and then analysed for the major physico-chemical quality parameters (pH, EC, major cations and anions) following standard test procedures. The status of groundwater for drinking was compared with WHO and other quality standards. Analytical analysis results indicated that majority of the considered quality parameters are rated above the prescribed tolerable limits for drinking set by WHO. About 97% of the water sample has water quality index in the range of very poor to unfit for drinking. The contamination index is in the ranges of low (–1.0) to high (3.6). In general, the groundwater of the area is unsuitable for human consumption without proper treatment such as boiling, chlorination, filtering, distillation, desalinaization, defluoridation, deionization, demineralization (ionexchange) and membrane processes. Since the TDS concentration is relatively small (<2000 ppm), demineralization process alone can be sufficient to bring the water to an acceptable level.

The study presents the results of the investigations of the effect of Cu, Ni, Cr, V, Mo and W alloy additions on the microstructure and

mechanical properties of the AlSi7Mg0.3 alloy. The examinations were performed within a project the aim of which is to elaborate an

experimental and industrial technology of producing elements of machines and devices complex in their construction, made of aluminium

alloys by the method of precision investment casting. It was demonstrated that a proper combination of alloy additions causes the

crystallization of complex intermetallic phases in the silumin, shortens the SDAS and improves the strength properties: Rm, Rp0.2,HB

hardness. Elevating these properties reduces At, which, in consequence, lowers the quality index Q of the alloy of the obtained casts.

Experimental casts were made in ceramic moulds preliminarily heated to 160 °C, into which the AlSi7Mg0.3 alloy with the additions was

cast, followed by its cooling at ambient temperature. With the purpose of increasing the value of the quality index Q, it is recommended

that the process of alloy cooling in the ceramic mould be intensified and/or a thermal treatment of the casts be performed (ageing)(T6).

Issues connected with high quality casting alloys are important for responsible construction elements working in hard conditions.

Traditionally, the quality of aluminium casting alloy refers to such microstructure properties as the presence of inclusions and intermetallic

phases or porosity. At present, in most cases, Quality index refers to the level of mechanical properties – especially strength parameters,

e.g.: UTS, YS, HB, E (Young’s Modulus), K1c (stress intensity factor). Quality indexes are often presented as a function of density.

However, generally it is known, that operating durability of construction elements depends both on the strength and plastic of the material.

Therefore, for several years now, in specialist literature, the concept of quality index (QI) was present, combines these two important

qualities of construction material. The work presents the results of QI research for casting hypoeutectic silumin type EN AC-42100

(EN AC-AlSi7Mg0.3), depending on different variants of heat treatment, including jet cooling during solution treatment.

In this research different methods for measuring water quality indices were conducted to investigate the performance of the newly designed, constructed and operated 9-Nissan water treatment plant, Iraq. Data gathering and implementation took place throughout winter and summer. Water samples were taken periodically, according to the standard method, the re-search was carried out by collecting different random samples for eight months (Jun. 2015–Jan. 2016) and measuring (tur-bidity, total hardness, pH, total dissolved solids, suspended solids, Cl–, Mg2+, Fe2+,NO3–, NH3+) for each sample. Five dif-ferent approaches and methodologies of calculating the water index were applied. The results revealed that the Water Qual-ity Indices varied from 70.55 to 88.24, when applying Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI) and British Columbia water quality index (BCWQI) geometric weighted mean respectively. All the results, from the five approaches indicated good water quality, multiple regression analyses were conducted for turbidity, total hardness and suspended solids, they found that these parameters are strongly related to each other and to other pa-rameters.