Pilot-Scale Microsand-Ballasted Flocculation of Wastewater: Turbidity Removal, Parameters Optimization, and Mechanism Analysis

The flocs formed during microsand-ballasted flocculation (MBF) have attracted much attention. However, few studies have reported on comprehensive process parameters of MBF and its mechanism is still not well understood. Jar test and pilot-scale continuous experiments were here conducted on two kinds of simulated wastewater, labeled S1 (21.6-25.9 NTU) and S2 (96-105 NTU). Results revealed the hydraulic retention time ratio in the coagulation cell, injection & maturation cell, lamella settler of pilot-scale MBF equipment was 1: 3: 7.3. The optimum poly aluminum chloride doses for Samples S1 and S2 were 0.875 g/L and 1.0 g/L. Besides, the optimum size of microsand was 49-106 µm and the optimum dose was 1.0 g/L. Under aforementioned conditions, the effluent turbidity of S1 was below 0.47 NTU, lower than the Chinese drinking water standard; that of S2 was below 1.7 NTU, meeting the Chinese recycled water standard. Turbidity removal ranged from 98.0% to 98.8% for S1 and 98.5% to 99.5% for S2 when microsand was added. Therefore, microsand addition enhances MBF performance, where microsand serves as an initial core particle. Some microsand core particles bond together to form a dense core structure of micro-flocs by the adsorption bridging of inorganic polymeric flocculant. Moreover, the size of the largest micro-flocs may be controllable as long as the effective energy dissipation ɛ0 is adjusted appropriately through specific stirring speeds. This work provides comprehensive pilot-scale process parameters for using MBF to effectively treat wastewater and offers a clearer explanation of the formation mechanism of microsand-ballasted flocs.

Effect of Magnesium on the Hydrophobicity of Sphalerite

The use of untreated recycled water has negative effects in the flotation of zinc sulfide ores due to the presence of dissolved species, such as magnesium and calcium. Although it has been found that magnesium is a more potent depressant than calcium, it has not been investigated in this role or for the effect of adding sodium carbonate. The results of an investigation to evaluate the effect of magnesium on the hydrophobicity of Cu-activated sphalerite conditioned with Sodium Isopropyl Xanthate (SIPX) are presented. Zeta potential of natural and Cu-activated sphalerite as a function of the conditioning pH and Cu(II) concentration, respectively, was first evaluated. Later, the effect of pH and presence of magnesium on the contact angle of Cu-activated sphalerite conditioned with SIPX was studied; it was also evaluated the effect of sodium carbonate to counteract the effect of magnesium. Cu-activation enhances the zeta potential of sphalerite up to a concentration of 5 mg/L. Contact angle tests, thermodynamic simulation, and surface analysis showed that magnesium hydroxide precipitates on the sphalerite surface at pH 9.6, decreasing its hydrophobicity. Addition of sodium carbonate as alkalinizing agent precipitates the magnesium in the form of a species that remained dispersed in the bulk solution, favoring the contact angle of Cu-activated sphalerite and, consequently, its hydrophobicity. It is concluded that the use of sodium carbonate as alkalinizing agent favors the precipitation of magnesium as hydromagnesite (Mg5(OH)2(CO3)4∙4H2O) instead of hydroxide allowing the recovery of sphalerite.

Basic Principles of Creating and Using the Waste-free Technologies in the System of Recycled Water Supply and Water Purification

The need to protect the environment makes it necessary to significantly change the general approaches to environmental efficiency of production, to minimize the impact on nature at the present level of productivity and quality. Today instead of the temporary measures aimed at overcoming the effects of pollution, the long-term measures are being taken more and more often at the design and construction stages to nullify the causes of pollution in advance rather than to have its effects in the future. The processes and devices that have been previously used to collect and dispose the industrial waste are now considered a passive approach to environmental protection. The matter is that the amount of waste generated during the production process remains almost unchanged, and this does not meet the new environmental requirements. The active approach involves creating the modern low-waste and non-waste technologies that can efficiently use raw materials in production processes, as well as converting the waste into easily recyclable components that are least harmful to the environment. The article considers the conceptual principles that show the essence of the active approach to improving the industrial technologies in order to protect the environment. It is mainly focused on studying the features of recycled water supply and water purification.

How Trust and Risk Perception Affect Household Water Use

Household water use accounts for an important portion of water consumption. Notably, different households may behave differently regarding how water is used in everyday life. Trust and risk perception are two significant psychological factors that influence water use behavior in households. Since trust and risk perception are malleable and subject to construction, they are useful for developing effective demand management strategies and water conservation policies. The concepts of trust and risk perception are multidimensional and interconnected. Risk perception varies across social groups and is often shaped by subjective feelings toward a variety of activities, events, and technologies. Risk perception is also mediated by trust, which involves a positive expectation of an individual, an organization, and/or an institution that derives from complex processes, characteristics, and competence. Likewise, different social groups’ trust in various entities involved in household water use is subject to the significant and far-reaching impact of risk perception. The complexity of the two notions poses challenges to the measurement and exploration of their effects on household water use. In many cases, risk perception and trust can influence people’s acceptance of water sources (e.g., tap water, bottled water, recycled water, and desalinated water) and their conservation behavior (e.g., installing water-saving technologies and reducing water consumption) in household water use. Trust can affect household water use indirectly through its influence on risk perception. Moreover, trust and risk perception in household water use are neither given nor fixed; rather, they are dynamically determined by external, internal, and informational factors. A coherent, stable, transparent, and fair social and institutional structure is conducive to building trust. However, trust and risk perception differ among groups with diverse household and/or individual demographic, economic, social, and cultural characteristics. Direct information from personal experiences and, more importantly, indirect information from one’s social network, as well as from mass media and social media, play an increasingly important role in the formation and evolution of trust and risk perception, bringing a profound impact on household water use in an era of information. Future directions lie in new dynamics of risk perception and trust in the era of information explosion, the coevolution mechanism of risk perception and trust in household water use, the nuanced impacts of different types of risks (e.g., controllable and uncontrollable) on household water use, and the interactive relations of risk perception and trust across geographical contexts.

KONSEP PEMAKAIAN DAUR ULANG GREYWATER UNTUK KEPERLUAN MCK SEKOLAH

Water is one of the natural resources that has very important role in the daily life of all living creatures. Mishandling of water might result in water catastrophe. Associates want to give learning to students regarding the environment, use water wisely, and do greywater recycling. Associates need help to make discussion topic regarding the use and saving also conceptual of greywater recycle for rest room necessity. Water treatment need to be done which is one of important factor to accomplish sustainable development related to our natural resources in this case is water. This devotion aim is to supply material to discuss between teachers and students about water necessity and give understanding to next generation regarding the important of clean water, to use water responsibly and understand greywater recycle. The output of greywater recycling can be used as an alternative water resource to solve the lack of water. Recycled water can be used for toilet and watering plant. Associate’s problem solving to introduce self-conscious the important of using water responsibly and also share knowledge about greywater recycle to next generation, by giving presentation to be discuss by students and teachers. Booklet will be use as discussion between students, and also included with conceptual drawing of greywater use for rest room at SMAN 96. Included in this service, prediction calculation of clean water being used per days in SMAN 96 based on teachers, and students during spring semester of 2020/2021 was provided. The calculation based on the number of active individuals at busy days and also according to SNI 037065-2005 and resulted with usage of 67 m3. When calculation was done based on holiday prediction then it will be saved as much 1968 m3 a year. Air merupakan salah satu sumber daya alam yang sangat dibutuhkan dalam kehidupan sehari-hari bagi mahluk hidup. Kesalahan dalam memanfaatkan/pemakaian air dapat mengakibatkan terjadinya krisis air. Mitra berkeinginan untuk melakukan semacam pembelajaran kepada siswa-siswanya tentang lingkungan hidup, pemanfaatan air secara bijak, dan melakukan daur ulang air limbah (greywater ). Mitra meminta dibantu membuatkan bahan diskusi tentang pemakaian dan penghematan serta konsep daur ulang greywater untuk keperluan MCK sekolah. Pengelolaan air perlu dilakukan yang merupakan salah satu bagian penting untuk mewujudkan pembangunan berkelanjutan terkait sumber daya alam yang kita miliki dalam hal ini adalah air. Pengabdian ini bertujuan memberi bantuan berupa bahan-bahan untuk diskusi antara guru dan siswa tentang kebutuhan air serta memberikan pemahaman kepada generasi penerus akan pentingnya air bersih dan menggunakan secara bijak pemakaian air serta mengerti daur ulang greywater . Hasil daur ulang greywater ini dapat dimanfaatkan sebagai sumber air alternatif guna mengatasi defisit air. Air hasil daur ulang dapat digunakan untuk keperluan MCK dan menyiram tanaman. Solusi permasalahan mitra untuk menanamkan kesadaran akan penggunaan air secara bijak serta memberikan pengetahuan akan daur ulang greywater bagi generasi penerus. dengan memberikan bahan presentasi/paparan untuk diskusi antara siswa dan guru. Bahan buku saku yang akan menjadi bahan diskusi diantara siswa, serta gambar konsep Pemakaian Daur Ulang Greywater untuk Keperluan MCK sekolah SMAN 96. Pada pengabdian ini juga dilakukan perhitungan perkiraan kebutuhan air bersih perhari di SMAN 96 berdasarkan dari data guru, tenaga didik dan peserta didik pada semester genap tahun ajaran 2020/2021. Hasil perhitungan ini berdasarkan jumlah manusia yang aktif pada hari sibuk dan perdasarkan peraturan SNI 037065-2005 yang diperoleh di sebanyak 67m3.Bila dilakukan perhitungan berdasarkan prediksi hari libur maka dapat dilakukan penghematan sebesar 1968m3 dalam setahun.

Improvement of Log Reduction Values Design Equations for Helminth Egg Management in Recycled Water

Understanding and managing the risk posed by helminth eggs (HE) is a key concern for wastewater engineers and public health regulators. The treatment processes that produce recycled water from sewage at wastewater treatment plants (WWTPs) rely on achieving a defined log10 reduction value (LRV) in HE concentration during the production of recycled water from sewage to achieve the guideline concentration of ≤1.0 HE/L. The total concentration of HE in sewage reaches thousands of HE/L in developing countries and therefore, an LRV of 4.0 is generally accepted to achieve a safe concentration in recycled water, as this will meet the guideline value. However, in many developed countries with good sanitation and public health standards, the HE concentration in sewage is generally <10 HE/L. Therefore, validation of the sewage treatment process relied on to achieve an LRV of 4.0 can be difficult. Because of these limitations, design equations to predict LRVs from hydraulic retention times (HRT), which are geographically non-specific, are commonly relied on to ensure the production of safe quality recycled water with respect to HE. However, these design equations could be further refined by defining the design and management of the treatment process in greater detail and thus be used more effectively for determining the LRV required. This paper discusses the limitations and possible improvements that could be applied to LRV design equations for predicting HE removal at WWTPs and identifies the data requirements to support these improvements. Several options for LRV design equations are proposed that could be validated experimentally or via the ongoing operation of WWTPs. These improvements have the potential to assist the rationalization of the HE removal requirements for specific treatment options, exposure scenarios and use of recycled water in agriculture.