Reduction of Ammonia Emissions from Laying Hen Manure in a Closed Composting Process Using Gas-Permeable Membrane Technology

Nitrogen losses during composting processes lead to emissions problems and reduce the compost fertilizer value. Gas-permeable membranes (GPM) are a promising approach to address the challenge of reducing nitrogen losses in composting processes. This study investigated the applicability of two GPM membrane systems to recover N released during the closed composting process of laying hen manure. The ammonia (NH3) capture process was performed using two different systems over a period of 44 days: the first system (S1) consisted of 120 m of an expanded polytetrafluoroethylene (ePTFE) membrane installed inside a 3.7 m3 portable, closed aerobic composter with forced ventilation; the second system (S2) consisted of 474 m of an ePTFE membrane placed inside as an external module designed for NH3 capture, connected to a closed aerobic composter through a pipe. In both cases, a 1 N H2SO4 acidic NH3 capture solution was circulated inside the membranes at a flow rate of 2.1 L·h−1. The amount of total ammonia nitrogen (TAN) recovered was similar in the two systems (0.61 kg in S1 and 0.65 kg in S2) due to the chosen membrane surface areas, but the TAN recovery rate was six times higher in system S1 (6.9 g TAN·m−2·day−1) than in system S2 (1.9 g TAN·m−2·day−1) due to the presence of a higher NH3 concentration in the air in contact with the membrane. Given that the NH3 concentration in the atmosphere of the membrane compartment directly influences the NH3 capture, better performance of the GPM recovery system may be attained by installing it directly inside the closed aerobic composters. Regardless of the chosen configuration, this technology allows N recovery as a stable and concentrated 1.4% N ammonium salt solution, which can be used for fertigation. The presented GPM systems may be used in community composting systems with low volumes of waste to be treated or in livestock facilities that have implemented best available techniques such as solid–liquid separation or anaerobic digestion, provided that the use of GPM technology in combination with these techniques also contributes to odor mitigation and improves biogas yields.

Ammonia volatilization from manure mixed with biochar

Ammonia (NH3) volatilization from ammonia-based fertilizer and animal manure reduces their nitrogen fertilizer value and is a source of environmental pollution. Mixing manure with biochar may lower NH3 volatilization from manure by adding H+, adsorbing mineral nitrogen (N), or increasing N immobilization in microbial biomass. The objective of this study was to determine whether wood-based biochar could lower NH3 volatilization from vented pails containing manure (liquid swine, dairy slurry, and solid poultry manure) or a urea ammonium nitrate solution (UAN). Two types of wood-based biochar (BlueLeaf and Dynamotive) were mixed with three types of manure and UAN fertilizer solution at 0, 2.5, 5, 10, and 25 % biochar by volume in vented pails. After 21 d storage in an outdoor shaded area, the greatest NH3 volatilization was from poultry manure, which had pH 9.4 on average and low water content regardless of the biochar source and application rate. There was less NH3 volatilization from UAN fertilizer solution when mixed with 25% (v/v) of Dynamotive biochar compared to NH3 volatilization from UAN fertilizer solution mixed with 0–10% (%) of Dynamotive biochar, probably because pH decreased from 7.0 to 6.4 after 21 d contact. Mixing wood-based biochar with manure had no impact on NH3 volatilization, suggesting that these biochar sources did not appreciably change the pH and N dynamics in stored manure after 21 d.

Enhancing the Fertilizer Value of Cattle Manure Using Organic Resources for Soil Fertility Improvement: A Review

The poor quality of cow dung in Ghana resulting from the opportunistic feeding mode of cattle impedes its adoption due to high quantities needed for application. This calls for nutrient optimization of cattle manure with inexpensive locally available sources of organic inputs that could enhance its quality. Though large volumes of crop residues and other agro-wastes are produced on-farm, they are underutilized and mostly a nuisance. Major food crops take approximately, 44 %, 42 % and 56 % of the total nitrogen (N), phosphorus (P) and potassium (K), respectively and are found in crop residues. There is therefore the need to develop appropriate technologies for utilizing agro-wastes by transforming them into useful “resources” with potentially available plant macro and micronutrients. Common agro-wastes in Ghana include cocoa pod husk (CPH), palm kernel cake (PKC), cattle manure (CM) and poultry manure. Hence, this review sought to explore the use of crop residues and agro-minerals to improve the quality of manure and consequently its fertilizer value for soil fertility improvement and increased crop yield. The review presented an assessment of resource potentials of some crop residues and local agro-mineral as a means of enhancing the quality of CM. Using published data, the review has identified that PKC, rock phosphate (RP) and CPH have high potential for improving the N, P and K contents of CM, respectively. In conclusion, it recommends the need to extensively explore the potential of other commonly available organic resource materials for their efficacy to improve the fertilizer value of cattle manure.

Assessment of the Short-Term Fertilizer Potential of Mealworm Frass Using a Pot Experiment

The forecasted growth of insect production in the next few years will generate high quantities of frass (insect excreta). Although frass is increasingly considered a potential fertilizer, the dynamics of nutrient supply by frass is still poorly understood. Here, we aimed at gaining insight into the short-term fertilizer value of frass from mealworm (Tenebrio molitor L.) in order to optimize its sustainable use in agroecosystems. Using a short-term pot experiment, we showed that, even though frass has a great potential to be used as a substitute of mineral NPK fertilizer, its N fertilizer potential is mediated by its rate of application. At 10 t ha−1, due to its fast mineralization coupled with improvement in microbial activity (assessed using Biolog EcoPlate), frass was as effective as mineral fertilizer to supply N to plant. By contrast, at 5 t ha−1, the lower frass mineralization induced a reduced N uptake compared to its mineral control. Unlike N, frass was as effective as mineral fertilizer to supply P and K to plants irrespective of its application rate. This was attributed to the presence of P and K in a readily available form in frass. Taken together, our results indicate that mealworm frass supplies very rapidly N, P and K to plants but its effects on N dynamics should be better investigated to warrant its sustainable use as an alternative fertilizer for managing NPK nutrition in cropping systems.

Urban Organic Waste for Urban Farming: Growing Lettuce Using Vermicompost and Thermophilic Compost

A transformation towards sustainable food production requires improved circular nutrient management. Urban organic waste contains relevant nutrients and organic matter, yet only 4% of global urban nitrogen (N) and phosphorus (P) sources are presently recycled. One recycling approach is the composting of urban wastes for urban horticulture. We characterized compost from various urban waste fractions and assessed their fertilizer value in a pot trial with lettuce plants. Seven treatments were investigated: food waste vermicompost with coir and paperboard bedding material, thermophilic compost from green waste and human feces, two references with mineral fertilization and a sand control. The lettuce yield and total uptake of P, potassium (K), calcium (Ca), and magnesium (Mg) were highest in plants grown in coir-based vermicompost. The fecal compost led to the highest shoot P and K content, but the shoot uptake of Ca and Mg were lower than in the other treatments. All composts required additional N for lettuce growth. In conclusion, urban waste-derived vermicompost and fecal compost demonstrate a high delivery rate of plant-available Ca, Mg, P, and K. Research is needed on macronutrient availability and alternative N sources for the substitution of synthetic fertilization. These findings support the production of urban waste composts, furthering efforts in nutrient recycling.

Use of Waste Generated during the Manufacture of Bioplastics from Sewage Sludge

There is an evolution and progress that has been taking place in recent years in science and technology and in the evolution of polymers that have created new plastic materials with excellent physical properties and durability. However, the plastic products that are made, generally have several applications, but for a single use, especially if it is in the part of food packaging, or for the pharmaceutical industry, in medical applications. Since these materials are not biodegradable, they remain on the surface of the earth for hundreds of years without considerable changes in their structure, causing pollution and damage to wildlife and the environment. With this research we intend to eliminate these plastics from petroleum derivatives, by biodegradable plastics. At the same time, the use of the generated by-products is sought, giving them an energy, thermal or fertilizer value.

Assessing the Effects of Digestates and Combinations of Digestates and Fertilizer on Yield and Nutrient Use of Brassica juncea (Kai Choy)

Anaerobic digestion of organic wastes produces solid residues known as digestates, which have potential as a fertilizer and soil amendment. The majority of research on digestate focuses on their fertilizer value. However, there is a lack of information about additional effects they may have on plant growth, both positive and negative. Understanding the effects of digestate on plant growth is essential to optimizing their use in agriculture and helping close the loop of material and energy balances. This greenhouse study evaluated the effects of two different digestates, a food waste digestate (FWD) and a lignocellulosic biomass digestate (LBD); a liquid fertilizer; and various combinations of fertilizer and digestates on plant growth, nutrient uptake and nutrient use efficiency (NUE) of Brassica juncea (kai choy) plants. It also evaluated potential negative attributes of the digestates, including salinity and possible biohazards. Combinations of LBD and fertilizer performed as well or slightly better than the fertilizer control for most parameters, including aboveground biomass and root length. These same combinations had significantly higher nitrogen use efficiency than the fertilizer control. Inhibitory effects were observed in 100% LBD treatments, likely due to the high electrical conductivity of the media from digestate application. Based on this research, LBD could partially replace mineral fertilizers for kai choy at up to 50% of the target nitrogen rate and may lead to increased plant growth beyond mineral fertilizers. FWD could replace up to 100% of the target nitrogen application, without causing significant negative effects on plant growth. Increasing the use of digestates in agriculture will provide additional incentives for the anaerobic digestion process, as it produces two valuable products: biogas for energy and digestate for fertilizer.

Evaluation of Microbiological Quality of Vermicompost Prepared from Different Types of Organic Wastes using Eisenia fetida

Background: Vermicomposting is the agricultural technique of conversion of organic wastes to a fertile product, which can result in better crop growth and production. However, even though earthworms are the main organisms participating in the process, the microbes associated with it also have an important role to play. These microbes degrade the waste products biochemically and are responsible of the conversion processes. Few studies are carried out on microbial diversity and related enzymes activities in the vermicompost prepared from different organic waste materials. Methods: In this paper, we isolated both bacteria and fungi from seven different types of vermicompost, using different selective media. We also studied the activity of hydrolytic enzymes that are associated with the isolated microbes.Result: It was observed that bacteria like Bacillus sp., Pseudomonas sp., Klebsiella sp., Staphylococcus aureus, Streptococcus, Micrococcus, Actinomycetes, Pigment producing Actinomycetes, Streptomyces, Azotobactor and fungi like Penicillium purpurogenum, Aspergillus sp., Alternaria alternata, Fusarium solani, Rhizopus sp., Mucor hiemalis, Myrothecium verrucaria etc. were present in our vermicompost preparations. The presence of nitrogen fixing bacteria, phosphate solubilizing microorganisms and PGPR indicated the good fertilizer value of the vermicompost samples. It was also observed that the diversity of microbes present supported significant levels of CMCase Exoglucanase, Xylanase, β-Glucosidase, Phosphatase and Urease activities.