Wastewater issues became a complex challenge in the world. There are several methods in wastewater treatment, such as chemical, physical, biological, and the combination of each method. However, each process has advantages and disadvantages. The physicochemical methods are common methods used in wastewater treatment, such as adsorption and coagulation. Adsorption and coagulation are excellent methods to remove pollutants. The adsorption process is greatly influenced by pH, adsorbent dose, temperature, and contact time. Coagulant dose, settling time, and pH are the main factors in the coagulation process. Chemical material as an adsorbent and coagulant has been studied in previous research, but recently, to substitution chemical materials is a challenging subject. Natural substances are potential new materials in wastewater treatment and became popular due to their efficiency and environment friendly characteristics. This review investigated the role of adsorption and coagulation in wastewater treatment and the utilization of natural materials as adsorbents and coagulants.

Dye wastewater contains dangerous chemical compounds, posing hazards to human health and the environment. This study investigates the efficacy of Hungarian rice husk (HRH) and Indonesian rice husk (IRH) as bioadsorbents for removing methylene blue (MB) from wastewater. The raw rice husks (RHs) were modified via hydrothermal carbonization to enhance adsorption efficiency. Characterization of the RHs was conducted through zeta potential measurements, Fourier transform infrared spectroscopy, and scanning electron microscopy. Batch adsorption experiments were carried out to evaluate the influence of various parameters, including pH, adsorbent dose, initial dye concentration, adsorbent particle size, and contact time on adsorption. The results indicate that the maximum dye removal was achieved at a contact time of 60 minutes. Hydrochar rice husks demonstrated slightly higher removal efficiencies than their raw rice husks. Adsorption kinetics followed the Elovich model, while the BET multilayer isotherm model provided a superior fit to the experimental data for MB adsorption. The simulation of the monolayer adsorption model indicated that the Langmuir isotherm provided the best fit for the experimental adsorption data. The adsorption capacities of HRH and IRH were 52.23 mg/g and 47.92 mg/g, respectively. The regeneration of RHs after adsorption–desorption cycles required using hydrochloric acid as a desorbing solution in four cycles. The recovered MB dye was reused for coloring cotton fabrics with ΔE* color values consistently below 5, indicating acceptable color differences. These findings suggest that RHs possess considerable potential as bioadsorbents for removing MB from wastewater.

Methylene blue (MB) and basic red 9 (BR9) are cationic dyes that are commonly used in the dye industry and negatively affect humans and other living organisms. This study compares the performance of Indonesian rice husk (IRH) and Hungarian rice husk (HRH) as bio-adsorbents for removing MB and BR9 from aqueous solutions. Chemical content, zeta potential, and Fourier-transform infrared spectroscopy analyses were used to characterize the rice husks (RHs). Adsorption studies were performed through batch experiments involving several parameters, namely, pH, adsorbent dose, initial dye concentration, contact time, and temperature to observe the self-association (aggregation) of MB and BR9. Adsorption kinetic studies showed that maximum dye removal was achieved at a contact time of 120 min. MB and BR9 adsorption followed a pseudo-second order kinetic model, and the BET multilayer isotherm model provided a better fit to the experimental data of MB and BR9 adsorption. The IRH adsorption capacities were 15.0 mg/g for MB and 7.2 mg/g for BR9, whereas those of HRH were 24.4 mg/g for MB and 8.3 mg/g for BR9. Therefore, these RHs are potential bio-adsorbents for removing MB and BR9 from aqueous solutions.

The rising of education with an environmentally friendly approach becomes one of the focuses on implementing sustainable growth of social life. This principle includes an attempt to develop the ecologically friendly pesantren. Along the time, pesantren is identified as a religion and social center. Meanwhile, its surrounding environment has not become the primary priority. This paper sought to analyze the activity of community service related to initiating the perspective change of pesantren. The study implies that pesantren not only an education institute practicing educational activity, but also become an agent of change for creating a better social life and society around, and further, to perform the environmentally friendly pesantren. The research used the literature review approach to propose the Eco-Pesantren strategy, the benefits and social-economic impact for pesantren and the greater community. Moreover, the Eco-Pesantren concept becomes the basis and good characteristic learning with concern for the environment. Furthermore, environmental theology brings Eco-Pesantren on the profound philosophy of eco-ethical perspectives.

The dairy industry generates large quantities of nutrient-rich by-products, particularly cheese whey, and buttermilk, which are valuable sources of bioactive proteins and phospholipids. Whey proteins exhibit notable therapeutic potential, offering various health benefits such as antihypertensive effects, immune modulation, and opioid antagonism. Similarly, buttermilk-derived phospholipids demonstrate bioactive properties, including cholesterol reduction, anti-inflammatory activity, and neuroprotective effects. This review critically assesses recent advances in protein separation techniques, comparing conventional thermal methods, known to potentially compromise protein functionality, with emerging non-thermal approaches such as high-pressure processing and membrane filtration, which enable efficient recovery while preserving bioactivity. Additionally, advanced methodologies such as multi-level processing and enzymatic hydrolysis further expand the protein separation techniques. Key technical challenges, including high mineral content in whey and the low solids concentration in buttermilk, are discussed alongside potential innovative solutions. Whey’s elevated mineral levels can reduce protein isolation efficiency and diminish the emulsifying properties of whey proteins, potentially restricting their functional applications. Meanwhile, the low total solids content in buttermilk poses challenges in achieving high protein concentration yields, requiring advanced separation techniques. Further, this review examines contemporary trends in cheese whey and buttermilk valorization, highlighting their opportunities for enhanced food applications. It also explores cross-sectoral utilization in biofuels, biodegradable materials, pharmaceuticals, and agriculture, supporting economic and sustainability goals in the dairy sector.