Brine sludge waste from a Chlor-alkali industry: characterization and its application for non-structural and structural construction materials

Brine sludge (BS) is an industrial waste generated in large amounts by the Chlor-alkali industry and, usually disposed into industrial landfills. Because BS contains several chemical compounds, also presents a potential environmental impact. The feasibility of the utilization of brine sludge wastes for the preparation of value-added materials was investigated. The characterization of two brine sludge samples was performed in terms of chemical and physical composition, particle size distribution, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and thermal analysis (DTA/TG). Elements like Ca, Si, Na, Mg, Al, Cl, and Fe were identified in the samples. The XRD results confirmed the crystalline nature of compounds and indicated that the main compounds in brine sludge samples were calcium carbonate, sodium chloride, magnesium hydroxide, and quartz. FTIR showed the presence of varying functional groups like carbonate, siloxane, and hydroxide. The two brine sludge samples can be considered as a fine powder with the mean diameter (d50) of 4.984 µm and 24.574 µm, for the BS from Santo André and Cubatão, respectively. The results indicated that the brine sludge samples presented favorable characteristics to use limestone filler and binder alternative to Portland cement in the nonstructural construction materials. The incorporation of brine sludge in geopolymeric materials is another possible use in sustainable construction material products. The production of value-added products from brine sludge will be an important contribution towards sustainable development adopted by the Chlor-alkali industry.

Production of Biodiesel using Calcined Brine Sludge Waste from Chor-Alkali Industry as a Heterogeneous Catalyst

Biodiesel is an environmentally friendly fuel, produced by a transesterification process using homogeneous catalyst which causes water pollution and cannot be recycled. The present study utilizes industrial brine sludge waste (IBSW) as a heterogeneous catalyst in the transesterification of waste cooking oil (WCO) into biodiesel. One variable at a time design was applied to optimize the transesterification process. The process variables were varied as follows: methanol to oil weight ratio (10–50 %), reaction time (0.5–2.5 h), reaction temperature (30–90 °C) and catalyst to oil weight ratio (0.84–4.2 %). The IBSW before and after calcination and the transesterification process was characterized using X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy and scanning electron microscope (SEM). Biodiesel was produced at maximum yield of 95.51 wt% at reaction time, temperature methanol to oil weight ratio, and catalyst to oil weight ratio of 1 hour, 60 °C, 30 wt%, and 2.52 wt% respectively. The FTIR and SEM results confirms that before and after the transesterification process the modification of IBSW took place. Using the ideal process conditions, biodiesel was produced and vital fuel properties such as viscosity, density, pour point and flash point were measured and were found to be within the specification as per American Society for Testing and Material (ASTM) standards for biodiesel. The reusability of the IBSW catalyst was tested by recycling and it can be established that the catalyst can be utilized up to four times without affecting its catalytic activity.

Utilization of Brine Sludge in Controlled Low Strength Materials (CLSM)

Controlled low-strength materials (CLSM) have begun to apply in a lot of countries because CLSM could distribute randomly in complex sites. Manufacturing from chlor-alkali industry, the brine sludge was used to replace the composition in CLSM for resource application. In this study, the mix composition of brine sludge replaced only the fine aggregates or all of the aggregates. Examining the suitable composition, the ball drop test and the compressive strength test were carried out. The ball drop test was applied to determine the readiness of the CLSM to accept loads prior, and the bearing capacity at different ages were measured by the compressive strength test. The results of the ball drop test in different replacements was 7 - 11.5 cm. The replacement of fine aggregates satisified the rule of CLSM. Replacing all of the aggregates, the mixtures were over 7.6 cm, which meant that the early strength at 1 day were not sufficient. The value of compressive strength at 28 days was 1.709 - 21.37 kgf/cm2, conforming the requirement of CLSM. Overall, the mixture which replaced the fine aggregates met all the specified values of CLSM. In particular, the composition of coarse aggregates reduce to 250 kg/m3, the utalization of the brine sludge could be the most.

Utilization of Brine Sludge in Nonstructural Building Components: A Sustainable Approach

The characterization and influence of brine sludge on the properties of cement-fly ash-sludge binders are presented. The reaction products formed during the hydration of binder provide an interlocking framework to physically encapsulate the waste particles and are responsible for the development of strength. The utilization of brine sludge in making paver blocks and bricks and the effect of sludge concentration on the engineering properties of these products are also discussed. These results clearly exhibited that brine sludge up to 35 and 25% can safely be utilized for making paver blocks and bricks, respectively. The leachability studies confirm that the metals ions and impurities in the sludge are substantially fixed in the matrix and do not readily leach from there. The utilization of brine sludge in construction materials could serve as an alternative solution to disposal and reduce pollution.