~ 786 ~ International Journal of Chemical Studies 2018; 6(3): 786-791 P-ISSN: 2349–8528 E-ISSN: 2321–4902 IJCS 2018; 6(3): 786-791 © 2018 IJCS Received: 06-03-2018 Accepted: 10-04-2018 Jenny Anna Margaretha Departement of Industrial Waste Treatment, Politeknik AKA, Bogor, Indonesia Candra Irawan Departement of Analytical Chemistry, Politeknik AKA Bogor, Bogor, Indonesia Poppy Sri Lestari Departement of Industrial Waste Treatment, Politeknik AKA, Bogor, Indonesia Azkiyah Rahma Departement of Analytical Chemistry, Politeknik AKA Bogor, Bogor, Indonesia Erizal Tanjung PT. Prasadha Pamunah Limbah Industri, Bogor, Indonesia Correspondence Poppy Sri Lestari Departement of Industrial Waste Treatment, Politeknik AKA, Bogor, Indonesia The effectiveness of calcium hydroxide and sodium hydroxide as neutralizer in coagulation for reducing fluoride in hazardous wastewater Jenny Anna Margaretha, Candra Irawan, Poppy Sri Lestari, Azkiyah Rahma and Erizal Tanjung Abstract The use of coagulant in Hazardous wastewater treatment containing Fluoride can decrease the pH of waste water, so calcium hydroxide and sodium hydroxide compound has been added in the process which can increase the pH value. This experiment consists of the optimum dose determination and the test phases. The optimum dose determination phase was performed by coagulation process using jar test and testing phase on pH, fluoride content, total suspended solids, total dissolved solids, and Chemical Oxygen Demand (COD). The use of calcium hydroxide and sodium hydroxide to precipitate fluoride ions in wastewater was then tested for its effectiveness. The optimum dosage of coagulant to precipitate liquid waste of Hazardous wastewater containing fluoride was 2,222 mg/L. The addition of coagulant PFS 2,222 mg/L with a neutralizing agent of calcium hydroxide 2,500 mg/L (PFS/Ca (OH) 2 to decrease fluoride content, total suspended solids and COD more effective than PFS 2,222 mg/L with a neutralizing agent of sodium hydroxide 1,400 mg/L (PFS/NaOH). Keywords: calcium hydroxide, sodium hydroxide, coagulation, fluoride, hazardous wastewater Introduction Fluoride wastes are widely produced from various industrial processes such as steel, aluminum, copper, nickel and phosphate. The use of pesticides containing fluoride also affects fluoride in the soil source. One of the main sources of fluoride is in drinking water, other sources are found in foods, dental products such as toothpastes and mouthwashes, and fluoride dust and smoke from industries using fluoride in both salt and hydrofluoric acid [1] . Fluoride is an electromagnetic substance and not present in a state free in nature, but only present in the form of fluoride salts. Natural waters usually have fluoride contents of less than 0.2 mg/L. In groundwater the levels of fluoride reach 10 mg/L and in the sea waters around 1.3 mg/L. Wastewater quality standard of health activities of Fluoride concentration is maximum 2 mg/L [2] . Fluoride is a hazardous and toxic waste due to its corrosive nature. Its concentrations in excess of 1.7 mg/L can result in dyeing of tooth enamel known as mottling, and in excessive levels can cause bone damage. Poly Ferric Sulfate (PFS) is one of the chemical coagulants that cause the destabilization of the particle negative charge in the suspension that can help clear the waste water [3] . The addition of PFS into the wastewater may decrease the pH, so in processing it should be added calcium hydroxide and sodium hydroxide compounds which can raise the pH value. In general, the neutralization process is used to neutralize liquid waste that is too acidic or alkaline. However, in some types of wastewater containing dye, neutralization can reduce or even completely eliminate the color. Chemicals to neutralize the pH are selected by considering the price, the obtaining convenience and storage safety in addition to its effectiveness. Commonly used neutralizing chemicals are sodium hydroxide and calcium hydroxide [4] . Calcium hydroxide (CaOH) and sodium hiroxide (NaOH) are also used to precipitate fluoride ions in wastewater which are then tested for effectiveness before they are made on a large scale and applied to waste treatment. The nature of NaOH as a coagulant can make the colloid particles unstable, so that the particles are ready to form a flock.