Enhancement of simultaneous batik wastewater treatment and electricity generation in photocatalytic fuel cell

Bench-Scale Fixed-Bed Column Study for the Removal of Dye-Contaminated Effluent Using Sewage-Sludge-Based Biochar

Batik industrial effluent wastewater (BIE) contains toxic dyes that, if directly channeled into receiving water bodies without proper treatment, could pollute the aquatic ecosystem and, detrimentally, affect the health of people. This study is aimed at assessing the adsorptive efficacy of a novel low-cost sewage-sludge-based biochar (SSB), in removing color from batik industrial effluent (BIE). Sewage-sludge-based biochar (SSB) was synthesized through two stages, the first is raw-material gathering and preparation. The second stage is carbonization, in a muffle furnace, at 700 °C for 60 min. To investigate the changes introduced by the preparation process, the raw sewage sludge (RS) and SSB were characterized by the Brunauer–Emmett–Teller (BET) method, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy. The surface area of biochar was found to be 117.7 m2/g. The results of FTIR showed that some functional groups, such as CO and OH, were hosted on the surface of the biochar. Continuous fixed-bed column studies were conducted, by using SSB as an adsorbent. A glass column with a diameter of 20 mm was packed with SSB, to depths of 5 cm, 8 cm, and 12 cm. The volumes of BIE passing through the column were 384 mL/d, 864 mL/d, and 1680 mL/d, at a flow rate of 16 mL/h, 36 mL/h, and 70 mL/h, respectively. The initial color concentration in the batik sample was 234 Pt-Co, and the pH was kept in the range of 3–5. The effect of varying bed depth and flow rate over time on the removal efficiency of color was analyzed. It was observed that the breakthrough time differed according to the depth of the bed and changes in the flow rates. The longest time, where breakthrough and exhausting points occurred, was recorded at the highest bed and slowest flowrate. However, the increase in flow rate and decrease in bed depth made the breakthrough curves steeper. The maximum bed capacity of 42.30 mg/g was achieved at a 16 mL/h flowrate and 12 cm bed height. Thomas and Bohart–Adams mathematical models were applied, to analyze the adsorption data and the interaction between the adsorption variables. For both models, the correlation coefficient (R2) was more than 0.9, which signifies that the experimental data are well fitted. Furthermore, the adsorption behavior is best explained by the Thomas model, as it covers the whole range of breakthrough curves.

Environmental Awareness in Batik Making Process

One of the goals of Sustainable Development Goals (SDG) is to conserve natural resources, such as water, soil, air, and others. Poorly treated industrial effluents discharged into nearby water streams contribute to water pollution. This problem is notably worse among small- and medium-scale industries, such as the local batik industry, which cannot afford proper and costly wastewater treatment facilities in their premises. Batik entrepreneurs should adopt environmentally friendly methods by using currently available technologies. Therefore, this phenomenological study investigated the environmental awareness of three batik entrepreneurs in Malaysia via interviews. The data was analyzed using thematic analysis. The batik entrepreneurs have adopted different batik making processes but employed almost similar batik waste disposal methods. Despite some level of environmental awareness among the batik entrepreneurs, they still practiced poor environmental batik making and disposal methods due to the lack of affordable technology. The lack of exposure to environmental education, open mindset, the socio-cultural practice of batik making, and production cost influences environmental awareness among batik entrepreneurs. Authorities should advocate green batik making and regulate rules for any malpractice. Future studies should explore the effective technologies used to dispose of batik waste effluents to enable batik entrepreneurs to adopt environmentally friendly batik making and waste disposal methods.

Integrated physical-biological treatment system for batik industry wastewater: A review on process selection

Batik is well known as one of the unique identifiers of the Southeast Asian region. Several countries that still preserve the batik heritage are Malaysia, Indonesia, China and India. The Batik industry holds a significant place in Malaysia's craft-based industry. In Malaysia, batik motifs and patterns are mostly hand-drawn and painted directly on fabric, therefore, each one is unique. The players in the Batik industry are mostly small businesses and cottage industries, particularly in the states of Kelantan, Terengganu, Pahang, Sabah and Sarawak. However, their market growth and contribution are not synchronized with the treatment system. The wastewater generated by this industry rarely meets standard effluent requirements and regulations, thus worrying the authorities. Batik wastewater is categorized as one of the highly polluted wastewaters. The toxicity of pollutants from batik may reduce environmental quality and pose a risk to human health. Batik wastewater needs extensive treatment, since no complete and appropriate treatment has been applied for so many years in specific batik industries. This paper reviews the batik industry in Malaysia, its wastewater generation and the available current treatment practices. It discusses integrated treatments of coagulation-flocculation and phytoremediation technology as a batik wastewater treatment process with potential utility in the batik industry. This review may become part of the guidance for the entire batik industry, especially in Malaysia.

Novel application of a Z-scheme photocatalyst of Ag3PO4@g-C3N4 for photocatalytic fuel cells

A composite of Ag₃PO₄@g-C₃N₄ with the Z-scheme structure was synthesized, and used as the photoanode in a photocatalytic fuel cell (PFC). With the help of the Z-scheme design, both the degradation of tetracycline and the output of maximum power density (P_max) were greatly enhanced in this PFC system. The degradation rate of tetracycline in the Ag₃PO₄@g-C₃N₄ PFC was 2.53 times and 3.65 times that in the PFC systems with the Ag₃PO₄ photoanode and the g-C₃N₄ photoanode, respectively. The P_max of the Ag₃PO₄@g-C₃N₄ PFC was 6.06 μW cm^-2, which was 1.46 times and 90.4 times that of the Ag₃PO₄ PFC (4.16 μW cm^-2) and the g-C₃N₄ PFC (0.067 μW cm^-2), respectively. The possible mechanism was proposed. The Z-scheme photoanode could not only contribute to the separation of photogenerated carriers to achieve a high photocatalytic activity, but also reserve a good redox capacity. Additionally, aeration played an important role on the PFC performance. It was demonstrated that N₂ purging facilitated the electricity generation, while O₂ purging promoted the pollutant degradation.