Design, construction and testing of a floating hood biodigester prototype for municipal waste organic waste

This paper documented the design, construction and operation test of a floating hood biodigester prototype, using organic residues (ruminal content, blood, bovine excreta and viscera) from the municipal trail of Ciudad Valles, S.L.P., with the purpose of generating biogas. The components of the biodigester system considered were: loading duct, concrete biodigester tank, biogas pipeline, floating hood, gas reservoir, discharge duct and discharge tank. A biodigester with storage capacity in the 0.178 m3 floating hood was designed for a 30-day trial operation and storage of 0.120 m3 of organic waste mixture in the biodigester tank. As of day 17 of operation the daily average of biogas generated was 0.1801 m3. The composition of the biogas at day 30 of operation, showed a content of 59.4% of CH4. When performing the flame test, an intense blue coloration was obtained, which indicates that the biogas produced has a high calorific value that will allow heating and flammability.

Chemical characterization methods for biodegradable organic wastes with relevance for the composting process. Case study

The study aimed to develop some methods for the compositional characterization of biodegradable waste with relevance to the composting process at the laboratory level. For testing, four waste fractions were selected, such as waste-based on dehydrated sludge, waste from parks (leaves, branches), market waste (mixture of vegetable and fruit), and cardboard waste. For metals and phosphorus, several microwave digestion methods were applied. The ammonium nitrogen content (NH4-N) was determined using a number of extraction procedures (water, CaCl2, and KCl). Three certified reference materials were used for testing the validity of the results. Recovery percentages higher than 90% were obtained. The developed and validated methods are suitable for biodegradable waste characterization used in composting processes.

PENINGKATAN KEKUATAN TANAH ORGANIK DENGAN PENCAMPURAN EMPAT JENIS LIMBAH RAMAH LINGKUNGAN

Waste is one of the problems in Indonesia. Based on the Ministry of the Environment, each person produces an average of 0.8 kg of waste per day. The average waste per person will increase in line with the increase in people's welfare and lifestyle. Assuming 220 million Indonesians, waste reaches 176,000 tons per day. Accompanied by increasing population growth, the need for infrastructure development on land is increasing. Soils that is often used for construction land is organic soil. It has low soil bearing capacity values and soil improvement methods are commonly used. The general method usually is to mix the soil with better bearing capacity. To minimize costs, a physical stabilization system is carried out that can use soil improvement methods with waste. This can deal with 2 problems at once, where there is the use of certain types of waste and also the planning of organic soil stabilization with small carrying capacity. By doing a triaxial test on organic soil by mixing 4 different types of waste, it shows that the best waste mixture that can affect the bearing capacity of the soil in sequence is coconut husk, tile fragments, construction demolition debris, and chicken egg shells. ABSTRAKLimbah merupakan salah satu permasalahan di Indonesia, Berdasarkan informasi Kementerian lingkungan Hidup, setiap orang menghasilkan rata-rata 0,8 kg sampah per hari. Rata-rata limbah per orang akan meningkat sejalan dengan meningkatnya kesejahteraan dan gaya hidup masyarakat. Dengan asumsi 220 juta penduduk Indonesia, limbah mencapai 176.000 ton per hari. Diiringi dengan peningkatan pertumbuhan penduduk, maka kebutuhan pembangunan infrastruktur di lahan tanah semakin bertambah. Salah satu tanah yang sering dipakai untuk lahan konstruksi adalah tanah organik. Tanah organik memiliki nilai daya dukung tanah yang rendah dan biasa dilakukan metode perbaikan tanah. Metode umum yang biasa dilakukan adalah dengan melakukan pencampuran tanah dengan daya dukung yang lebih baik. Untuk memperkecil biaya maka dilakukannya sistem stabilisasi fisik yang bisa menggunakan metode perbaikan tanah dengan limbah. Hal ini bisa menangani 2 masalah sekaligus, dimana adanya pemanfaatan dari jenis limbah tertentu dan juga perencanaan stabilisasi tanah organik dengan daya dukung kecil. Dengan melakukin uji triaksial pada tanah organik dengan mencampurkan 4 jenis limbah berbeda menunjukan bahwa campuran limbah terbaik yang bisa mempengaruhi daya dukung tanah secara berurutan adalah sabut kelapa, pecahan genteng, puing pembongkaran konstruksi, dan cangkang telur ayam.

Chemically recyclable thermoplastics from reversible-deactivation polymerization of cyclic acetals

Identifying plastics capable of chemical recycling to monomer (CRM) is the foremost challenge in creating a sustainable circular plastic economy. Polyacetals are promising candidates for CRM but lack useful tensile strengths owing to the low molecular weights produced using current uncontrolled cationic ring-opening polymerization (CROP) methods. Here, we present reversible-deactivation CROP of cyclic acetals using a commercial halomethyl ether initiator and an indium(III) bromide catalyst. Using this method, we synthesize poly(1,3-dioxolane) (PDXL), which demonstrates tensile strength comparable to some commodity polyolefins. Depolymerization of PDXL using strong acid catalysts returns monomer in near-quantitative yield and even proceeds from a commodity plastic waste mixture. Our efficient polymerization method affords a tough thermoplastic that can undergo selective depolymerization to monomer.

Thermo-catalytic studies on a mixture of plastic waste and biomass

The effects of various catalysts on the composition of volatile pyrolysis products of a plastic waste and biomass mixture (1:1) were studied, by pyrolyzing the mixture sample using slow and fast heating rate. Various zeolite catalysts (β-and Y-zeolites, ZSM-5 and FCC) and nickel-molybdenum catalyst on alumina support were applied to find suitable catalysts for upgrading the quality of the thermal decomposition products of the waste mixture. A sample to catalyst ratio of 2:1 was used in the experiments. The rate of evolution of the decomposition products under slow pyrolysis was measured by thermogravimetry/mass spectrometry (TG/MS). The composition of the pyrolyzates was analyzed in detail by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) method. The influence of all applied catalysts was more pronounced on the plastic content of the sample than on biomass. The pyrolysis experiments revealed that the catalysts promoted the cracking reactions of the evolved hydrocarbons; furthermore, the formation of aromatic products was enhanced remarkably in the presence of all zeolite catalysts. Beta-zeolite and ZSM-5 catalysts were found the most effective in cracking hydrocarbons to gaseous products and in aromatization, while the highest CO2 formation was obtained by FCC from the biomass part of the studied waste mixture. NiMo catalyst promoted the H2 production from the plastic part; furthermore, slight aromatization and cracking effects were also observed.