This paper presents a preliminary study for the removal of COD and suspended solids in wastewater treatment by combining magnetic field and electrocoagulation (EC) technology. The experiments were carried out using batch apparatus and setup in the static method. Batch experiments with two monopolar iron (Fe) plate anodes and cathodes were employed as electrodes. Wastewater samples were prepared from milk powder with an initial COD of 1,140 mgL(-1) and suspended solids of 1,400 mgL(-1) and acidic conditions were employed (pH approximately 3). DC current was varied from 0.5-0.8 A and operating times were between 30 and 50 min. The results show that the effluent wastewater was very clear (turbidity approximately 9 NTU) and its quality exceeded the direct discharge standard. The suspended solids and COD removal efficiencies were as high as 30.6 and 75.5%, respectively. In addition, the experimental results also show that the electrocoagulation could neutralise the pH of wastewater.

Cilacap is one of the regions in Indonesia in the southern coastal region bordering the Indonesian Ocean. In the coastal areas of Cilacap including Kawunganten district, there are frequent floods due to sea level rise. Tidal flood problem in Cilacap can be overcome by constructing a moveable dam. The selection of moveable dam gateis needed so that it can be work optimally. Data in this study were obtained through a questionnaire and distributed to respondents who were experts in the field of water. There are 5 criteria used to select the type of moveable dam gate, namely material, function, operational and maintenance, cost and location. There are 4 alternatives of moveable dam gatenamely flap gate, radial gate, sliding gate and rubber dam. The results of the questionnaire were then processed using Analytical Hierarchy Process. The results showed that the most important criteria to select the type of moveable dam gate is cost (0.273). The best alternative of moveable dam gate based on all criteria is flap gate (0.291). Movable dam with flap gate became the priority because it is easy to operate and low cost. The best location for moveable dam placement is before Ujungmanik Bridge with a score 0.376.

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Design of experiments (DOE) is one of the statistical method that is used as a tool to enhance and improve experimental quality. The changes to the variables of a process or system is supposed to give the optimal result (response) and quite satisfactory. Experimental design can defined as a test or series of test series by varying the input variables (factors) of a process that can known to cause changes in output (response). This paper presents the results of experimental design of wastewater treatment by electrocoagulation (EC) technique. The objectives of this study were to investigate the suitability of magnetic fields and electrocoagulation technologies for the treatment of wastewater in enhancing removal of suspended solids and its sedimentation. A combined magnet and electrocoagulation (EC) technology were designed to increase settling velocity and to enhance suspended solid removal efficiencies from wastewater samples. In this experiment, a synthetic wastewater samples were prepared by mixing 700 mg of the milk powder in one litre of water and treated by using an acidic buffer solution. The monopolar iron (Fe) plate anodes and cathodes were employed as electrodes. Direct current was varied in a range of between 0.5 and 1.1 A, and flowrate in a range of between 1.00 to 3.50 mL/s. One permanent magnets namely AlNiCo with a magnetic strength of 0.16T was used in this experiment. The results show that the magnetic field and the flowrate have major influences on suspended solids removal. The efficiency removals of suspended solids, turbidity and COD removal efficiencies at optimum conditions were found to be more than 85%, 95%, and 75%, respectively.

Sand bags are one of the technologies still widely used to elevate water level. The sand bags are arranged in order to dam the river flow and to irrigate agricultural land, especially during the dry season. In line with its utilization, water supply of this technology is still less effective, thus, alternative technology is needed. This study aimed to test Barrier Knock-Down as an alternative technology that can be assembled and stored. This study was a quantitative research conducted by testing the prototypes. The tests were carried out using a monitor instrument Diver, piezometer. The tests of comparison were conducted in 4 types: Type 1, it was an L shape filled with sand+water; Type 2 was I shape filled with sand+water; Type 3 was an I shape filled with water; Type 4 was in an L shape filled with water. From the results of the study, type 1 is the best method for weir irrigation technology because of its ability to resist vertical and horizontal force than other types. Type 1-an L shape filled with sand+water with the value of safety factor rolling stability 5,28 and shear stability 2,23. Experiment result a stable elevation value in weir, did not experience a shift.