Characteristics of Low-Oxygen Oxidation Ditch with Improved Nitrogen Removal

This article presents a study on the operational stability of laboratory oxidation ditches, designated for synthetic and real wastewater and operable at low concentrations of dissolved oxygen. The project encompassed the stability monitoring of activated sludge depending on sedimentation characteristics and hydrobiological indicator microorganisms, determining (1) the size of sludge floccules and (2) the main functional groups of microorganisms identified in the course of the PCR analysis and reaction rates, plotted using the Michaelis–Menten enzymatic kinetics for the mixed culture biomass. The most stable system involves a bioreactor featuring dissolved oxygen gradients that range from 1.9 to 0.15 mg/L s, a specific organic load of 0.21 gBOD/g/d and a hydraulic retention time of 12 h. A built-in settling tank allows the consideration of the potential generation of large floccules of activated sludge in oxidation ditches (at least 300 μm) that increase the efficiency of simultaneous nitrification and denitrification. Thus, the obtained reaction rates can be used in calculations and simulations of the operation of oxidation ditches at low concentrations of dissolved oxygen.

Studi Preferensi Pemilihan Merek Dekanter 3 Fasa pada Pabrik Kelapa Sawit menggunakan Analytic Hierarcy Process

Dekanter digunakan untuk memisahkan fasa minyak dari sludge underflow continuous settling tank (CST) pada unit klarifikasi di Pabrik Kelapa Sawit (PKS). Jenis dekanter yang umum digunakan di PKS adalah dekanter 3 fasa. Tulisan ini membahas tentang preferensi pemilihan merek dekanter 3 fasa dengan menggunakan metode analisis Analytic Hierarchy Process (AHP). Sebelum dilakukan analisis AHP, koresponden ahli membuat daftar kriteria dan sub-kriteria pemilihan dekanter. Analisis AHP dilakukan tiga tahap, yaitu: i) pengelompokan kriteria, ii) penilaian perbandingan silang kriteria dan sub-kriteria oleh koresponden user, dan iii) penilaian perbandingan kriteria dan sub-kriteria terhadap merek dekanter oleh koresponden user. Analisis AHP menggunakan software Expertchoice® versi 11. Hasil analisis tahap pertama AHP berupa: i) daftar pertanyaan hubungan kriteria dan sub kriteria terhadap merek dekanter yang tersusun dalam kuesioner, dan ii) bobot nilai untuk setiap pertanyaan. Sebanyak 10 orang koresponden user diwawancara untuk menjawab pertanyaan kuisioner. Seluruh data dari kuisioner diinput ke dalam platform analisis. Hasil analisis tahap kedua AHP menunjukkan bahwa kriteria teknis menjadi preferensi utama konsumen dibandingkan kriteria ekonomi. Nilai preferensi tertinggi sub-kriteria ekonomi adalah ketersediaan spare part (KSP), nilai preferensi tertinggi sub-kriteria teknis adalah losis minyak (LM). Hasil analisis tahap ketiga AHP adalah dekanter Merek B berada pada peringkat pertama, dengan nilai preferensi ekonomi 0,148 dan teknis 0,130. Hasil ini menunjukkan bahwa nilai preferensi dapat berubah jika melibatkan analisis yang kompleks antara kriteria, sub-kriteria dan merek dekanter. Hasil analisis sensitifitas menunjukkan bahwa dekanter Merek B dan Merek E menjadi peringkat pertama preferensi, dimana Merek E berada pada rangking ketiga sebelum analisis sensitifitas.

Theoretical and Experimental Studies of Uneven Dust Suction from a Multi-Cyclone Settling Tank in a Two-Stage Air Filter

In this paper, the uneven air stream distribution problem of individual cyclones is studied in the multi-cyclones of intake air filters in special vehicles’ engines. This problem increases in multi-cyclones, in which several dozen cyclones have a common dust trap from which the collected dust is continuously removed by ejection suction. The aim of this study is the recognition of the theoretical and experimental possibility of reducing the streams’ unevenness, which should result in an efficiency increase in multi-cyclone separation. The methods that led to obtaining a relative stream uniformity from the suction of individual cyclones was analyzed. The method for creating equal pressure drops between the suction streams in the channels was used to achieve this goal. For this purpose, the internal structure of the multi-cyclone settler was changed. The multi-cyclone settling tank space was divided by vertical partitions into independent segments. The settling tank segment was then divided with horizontal shelves into suction channels of different heights, which were assigned a specific number of individual cyclones. The suction channels’ height was theoretically selected in terms of the equal resistance to air stream flow through the channels. For this purpose, the multi-cyclone dust settler segment model was developed. The theoretically determined suction channel’s height was verified by performing experimental flow tests in four (A, B, C, D) dust settler variants. Suction streams of satisfactory uniformity from the cyclones of the variant D settling tank were obtained at a level of 5%. In the next stage, experimental tests of the segment cyclones were carried out with dust before and after the division into suction channels of variant D for the settling tank. A significant increase was achieved from 93.73% to 96.08% in the cyclones’ separation efficiency, which were located as far away from the suction stub as possible and led to a reduction in the non-uniformity of cyclone efficiency in the segment. It follows that the multi-cyclone dust settling segment’s internal structure change gave the expected results.

Super-bridging Fibrous Materials for Water Treatment: Impacts on Removal of Plastic Particles, Phosphorus and Natural Organic Matter

To deal with issues of process sustainability, cost, and efficiency, we developed materials reengineered from fibers to serve as super-bridging agents, adsorbents, and ballast media. These sustainable fiber-based materials considerably increased the floc size (~6630 µm) compared to conventional physicochemical treatment using a coagulant and a flocculant (~520 µm). The materials also reduced coagulant usage (up to 40%) and flocculant usage (up to 60%). These materials could be used in synergy with coagulants and flocculants to improve settling in existing water treatment processes and allow facilities to reduce their capital and operating costs as well as their environmental footprint. Moreover, the super-sized flocs produced using fiber-based materials (up to ~13 times larger compared to conventional treatment) enabled easy floc removal by screening, eliminating the need for a settling tank, a large and costly process unit. The materials can be effective solutions at removing classical (e.g., natural organic matter (NOM) and phosphorus) and emerging contaminants (e.g., microplastics and nanoplastics). Due to their large size, Si- and Fe-grafted fiber-based materials can be easily recovered from sludge and reused multiple times.

Reduction of COD and Highly Coloured Mature Landfill Leachate by Tin Tetrachloride with Rubber Seed and Polyacrylamide

Tin tetrachloride (SnCl4) as a coagulant and rubber seed (Hevea brasiliensis) (RS), and polyacrylamide (PAM) as the coagulant aid were investigated in this work to treat matured and stabilised landfill leachate rich in COD and colour. A standard jar test was conducted at different pH values and dosages of coagulant/coagulant aid. When SnCl4 acted as the primary coagulant, the optimum conditions occurred at pH 8 and 10,000 mg/L dosages, with 97.3% and 81% reductions of colour and COD, respectively. Both RS and PAM were not effective when used alone. When RS was used as the coagulant aid, the dosage of SnCl4 was reduced to 8000 mg/L. The colour reduction was maintained at 97.6%, but the COD removal dropped to 43.1%. In comparison, when PAM was supplemented into 6000 mg/L SnCl4, the reduction in colour was maintained at 97.6%, and the COD removal was almost at par when SnCl4 was used alone. The addition of polymers as the coagulant aid helped in improving the sludge properties with a better settling rate (SSR) and larger flocs size. The decline of the SVI value indicates that less amount of sludge will be disposed of after the treatment. In addition, the rise of settling velocity (SSR) will reduce the size of the settling tank used in coagulation-flocculation treatment. Based on the results, it can be concluded that incorporation of coagulant aid into the treatment reduced the primary coagulant dosage without affecting the removal performances of pollutants.

Super-bridging Fibrous Materials for Water Treatment: Impacts on Removal of Plastic Particles, Phosphorus and Natural Organic Matter

Aggregation combined with gravitational separation is the most commonly used method to treat water globally, but it carries a significant economic and environmental burden as the chemicals used in the process (e.g., coagulants) generate ~8 million tons of metal-based sludge waste annually. To simultaneously deal with the issues of process sustainability, cost, and efficiency, we developed materials reengineered from pristine or waste fibers to serve as super-bridging agents, adsorbents, and ballast media. This study shows that these sustainable fiber-based materials considerably increased the floc size (~6630 µm) compared to conventional physicochemical treatment using a coagulant and a flocculant (~520 µm). The fiber-based materials also reduced coagulant (up to 40%) and flocculant usage (up to 60%). Moreover, the unprecedented size of flocs produced using fiber-based materials (up to ~13 times larger compared to conventional treatment) enabled easy floc removal by screening, thereby eliminating the need for a settling tank, a large and costly process unit. Our results show that fiber-based materials can be effective solutions at removing classical (e.g., natural organic matter (NOM) and phosphorus) and emerging contaminants (e.g., microplastics and nanoplastics). Due to their large size (> 3000 µm), some Si-grafted and Fe-grafted fiber-based materials can be easily recovered from settled/screened sludge and reused multiple times for coagulation/flocculation. Our results also show that these materials could be used in synergy with coagulants and flocculants to improve settling in existing water treatment processes. Furthermore, these reusable materials combined with separation via screening could allow global water treatment facilities to reduce their capital and operating costs as well as their environmental footprint.

Pilot-scale study based on integrated fixed-film activated sludge process for cement industrial wastewater treatment

Due to the lack of freshwater resources in Egypt, cement wastewater treatment was performed to widen the range of the water used in irrigation to face the massive future water scarcity. In this study, integrated fixed-film activated sludge (IFAS) was used as a biological treatment method. A laboratory pilot was established as a simulation of the IFAS process. The scale-pilot consists of a primary sedimentation tank, an IFAS tank equipped with an air blower, and a final settling tank. Three experimental attempts were performed using 3 different bio-carriers. In the first trial, Luffa sponges were used as natural bio-carriers and polyurethane sponges (PU) as artificial bio-carriers in the second trial, in addition to a combination between Luffa and PU sponges as a hybrid bio-carrier in the third trial. After analyzing the physicochemical properties of wastewater at the national research center in Cairo, the removal efficiency of TSS (total suspended solids), COD (chemical oxygen demand) , BOD(biological oxygen demand), TN (total nitrogen), and TP (total phosphorous) was 94.5%, 87.8%, 90.8%, 75.9%, and 69.4%, respectively in case of using the combination between Luffa and PU sponges. It can be concluded that using IFAS process was effective for cement wastewater treatment and the effluent wastewater met the Egyptian code limitations for reuse in agriculture purposes.

Influence of filter elements on the operation of tribomechanical systems

Oil filter is a part of a gasoline or diesel engine lubrication system designed to clean the engine oil. Depending on where it is installed, the oil filtration system, they are divided into three types: - through-flow filter, which passes through all the oil that the pump feeds into the engine. A pressure regulating by-pass valve is installed upstream of the filter to protect the gaskets with oil seals. If the filter element is too dirty, the valve directs oil flow past the filter, preventing oil starvation of the bearings. Keeps engine from failing due to lack of lubrication; - a partial-flow filter is mounted parallel to the main oil line and cleans only a portion of the oil that enters the engine. Gradually the whole volume of oil passes through the filter element, giving a fairly high cleaning efficiency. However, this method does not provide absolute protection of parts from chips and other abrasives; - the combination filter combines a full-flow and a partial-flow cleaning principle. It consists of two filter elements, one mounted parallel to the oil line and the other cut into it. This ensures maximum cleaning efficiency and long filter life. The filter elements are divided into two types according to their efficiency in removing fine impurities: coarse filters, which remove coarse impurities, and fine filters, which remove fine impurities. According to the design of the housing and the possibility of replacing the filter element, filters are divided into multiple (collapsible) and disposable (non-collapsible). Modern engines may use filters in the form of a cartridge, which is inserted into a special compartment. During operation, the oil is first routed to the filter and then through the oil channels to the interacting parts in the engine. This principle is used on all standard passenger cars. A settling filter (gravity filter) is a tank with a filter element and a settling tank in which impurities are deposited by gravity. The centrifugal filter operates similarly to the gravity filter, only dirt settles in it under the action of centrifugal force resulting from the rotation of the body

Sustainable Fiber-Based Materials as Super-bridging Agents, Adsorbents, and Ballast Media

Aggregation combined with gravitational separation is the most commonly used method to treat water globally, but it carries a significant economic and environmental burden as the chemicals used in the process (e.g., coagulants) generate ~8 million tons of metal-based sludge waste annually. To simultaneously deal with the issues of process sustainability, cost, and efficiency, we developed materials reengineered from pristine or waste fibers (e.g., cellulose, polyester, cotton, and keratin) to serve as super-bridging agents, adsorbents and ballast media. This study shows that these sustainable materials (fibers, microspheres, and flakes functionalized with Si, Al and/or Fe) considerably increased the floc size (~6630 µm) compared to conventional physicochemical treatment (~520 µm; using alum and polyacrylamide). The fiber-based materials also reduced chemical usage (20–60 %) and improved contaminant removal during settling by increasing floc size and density. Moreover, the unprecedented size of flocs produced using fiber-based materials (13 times larger compared to conventional treatment) enabled easy floc removal by screening, thereby eliminating the need for a settling tank, a large and costly process unit used to treat more than 70% of water globally. Our results show that fiber-based materials can be effective solutions at removing classical (e.g., natural organic matter (NOM) and phosphorus, via electrostatic affinities) and emerging contaminants (e.g., microplastics and nanoplastics). Due to their large size (> 3000 µm), some Si-grafted and Fe-grafted fiber-based materials were easily recovered from settled/screened sludge and reused multiple times for coagulation/flocculation. These reusable materials combined with separation via screening could allow global water treatment facilities to reduce their capital and operating costs as well as their environmental footprint. Finally, our results also show that these materials could be used in synergy with coagulants and flocculants to improve existing water treatment plants for the removal of NOM, phosphorus, turbidity, total suspended solids and microplastics.