Environmental Abstracts

The efficiency of a semi-continuous three-stage bioreactor and application possibilities of a chicken manure substrate with birch wood biochar additive (10% by a dry mass) were investigated in this work to evaluate a possible increase in biogas yield, CH(4)concentration and to reduce CO(2)and H2S concentrations. A biogas purification filter-adsorber has been investigated in order to efficiently purify biogas from H2S and CO2. A chicken manure substrate with an organic load of 100.0 g VS/L was used for testing. Studies have shown that the application of the birch wood biochar additive increases the yield of biogas by 12.4%, the concentration of CH(4)by 5.8%, and reduces the concentration of CO(2)and H2S by 4.0% and 17.5%, respectively. The intermediate chamber of the bioreactor, used for the optimization of the substrate, reduces the dissolved oxygen by 80.5%. Homogeneous mixing of the substrate with a modified complex mixer increases the yield of biogas by 42.3%, CH(4)concentration by 14.3%, reduces CO(2)and H2S concentrations by 25.5% and 45.6%, respectively. The efficiency of the biogas purification filter-adsorber was determined (99.2% for purifying biogas from H2S and 19.2% for purifying biogas from CO2).

Novel composite materials have been prepared by primary paper sludge (PS) and biopolymer (modified corn starch (MCS). The MCS is used as a binder. The aim of the research was to investigate the properties, microstructure and durability (water erosion) of composite materials (CM). The CM were formed from 100 wt% of paper sludge and 20 wt% of various concentrations (2.5%, 5.0% and 7.5%) of MCS were added. Corn starch was heated 3 h at 150 °C temperature. The CM produced had a bulk density of 0.89–1.18 g/cm3, compressive strength at 10% relative deformation 4.8–9.3 MPa, thermal conductivity 0.092–0.132 W/m·K. Additionally, this study underscores that the CM show good durability (resistance to water erosion) and hygrothermal qualities. In fact, the MSC solution incorporated in the paper sludge showed improved physical-mechanical properties and durability of the CM. The research shows that CM can be formed from paper sludge and MCS, and these can be used as indoor masonry units because they also have good mechanical, hydroscopic and thermal insulation properties.

Biochar, which is rich in aromatic carbon and minerals, is a product of biomass pyrolysis at temperatures ranging from 350ºC to 1000ºC in oxygen-limited environments. In recent years biochar has generated much interest in the field of water treatment in view of low production costs, availability of the feedstock (e.g., lignocellulosic biomass waste) and adsorptive properties. The aim of this study was to evaluate the effect of modifying biochar with H2 O2 on its adsorptive characteristics. The novelty of this study was investigating the influence of H2 O2 modification process parameters (concentration of H2 O2 solution, biochar particle size, rotation during modification) on the physico-chemical properties of biochar, such as bulk density, elemental composition, moisture, ash content, pH, electrical conductivity, cation exchange capacity, specific surface area, and content of oxygen-containing functional groups. We found that 30% concentration of H2 O2 solution, rotation at 3 rpm, and particle size 0.4-1 mm favor the modification process.

With stricter requirements for wastewater treatment, small-scale individual wastewater treatment plants can provide a financially attractive alternative to a sever connection in locations far from the existing sewer network. Systems operating under the basis of active sludge are considered advanced, and their producers declare high levels of wastewater treatment not only according to BOD, but also under biogenic materials. However, there are hardly any data on how small-scale individual household wastewater treatment facilities operate. This article presents an analysis of the main parameters of wastewater biologically treated in three small-scale household wastewater treatment plants (which operate under the basis of active sludge), namely TSS, COD, BOD7, Nt, NO3-N, NH4-N, Pt, and PO4-P concentrations. The research lasted for 5.5 months during a cold period. According to TSS, COD, and BOD7 concentrations in effluent, the wastewater treatment level in the study plants was good. The concentrations of these substances in effluent (TSS<10 mg/L, COD<98 mg/L, BOD7<20 mg/L) were lower than requirements for treated water. However, NH 4-N in the effluent in winter increased up to 6-7 mg/L and to 26 mg/L. The concentrations of Nt and Pt in treated wastewater exceeded EU requirements for water released from wastewater treatment facilities. PO4-P removal, in many cases, was ineffective or did not take place at all.