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Organic waste has the potential to produce methane gas as a substitute for petrol-based fuels, while reducing landfilling and possible environmental pollution. Generally, anaerobic digestion (AD) is used only in wastewater treatment plants as a tertiary stage of sewage sludge treatment, generating a fraction of the energy that such process plants require. In this study, four different wastes—food waste (FW), dairy industry waste (DIW), brewery waste (BW), and cardboard waste (CBW)—were tested for biogas production. The biochemical methane potential (BMP) of each sample was evaluated using an automatic methane potential system (AMPTS). Operating parameters such as pH, temperature, total solids, and volatile solids were measured. Experiments on the anaerobic digestion of the samples were monitored under mesophilic conditions (temperature 37 °C, retention time 30 days). Specific methane yields (SMYs), as well as the theoretical methane potential (BMPth), were used to calculate the biodegradability of the substrates, obtaining the highest biodegradability for BW at 95.1% and producing 462.3 ± 1.25 NmL CH4/g volatile solids (VS), followed by FW at an inoculum-to-substrate ratio (ISR) of 2 at 84% generating 391.3 NmLCH4/g VS. The BMP test of the dairy industry waste at an inoculum-to-substrate ratio of 1 was heavily inhibited by bacteria overloading of the easily degradable organic matter, obtaining a total methane production of 106.3 NmL CH4/g VS and a biodegradability index of 24.8%. The kinetic modeling study demonstrated that the best-fitting model was the modified Gompertz model, presenting the highest coefficient of determination (R2) values, the lowest root means square error (RMSE) values for five of the substrates, and the best specific biogas yield estimation with a percentage difference ranging from 0.3 to 3.6%. [ABSTRACT FROM AUTHOR]

Anaerobic liquid dairy digestate is a by-product of dairy waste anaerobic digestion from dairy operations and is associated with environmental risks if not handled properly, particularly nutrient leaching losses, water contaminations, and greenhouse gas emissions. We tested the applications of anerobic digestate (AD) as a biofertilizer and water source in greenhouse vegetable production to integrate food production and industry waste management for sustainable environments. We used a deep water culture system to assess the effects of AD effluent alone, inorganic nutrient solution (NS), and a combination of AD and NS on the growth, yield, and phytonutrient profile and heavy metal contamination assessment of hydroponically produced lettuce. Lettuce produced in AD had a lower leaf area, total chlorophyll content, and fresh biomass; however, it displayed significantly higher chicoric acid (200%), chlorogenic acid (67%), luteolin (800%), quercetin-3-O-β-d-glucuronide (378%), quercetin-3-glucoside (200%), quercetin-3-O-(6″-O-malonyl)-β-D-glucoside (1077%), folate (248%), pantothenic acid (200%), total phenolics (111%), total antioxidants (44%), and soluble sugars (253%) compared to control (inorganic feed). The AD-produced lettuce also showed significantly lower heavy metal bioaccumulation risks associated with the human consumption. Based on various results, we may conclude that AD utilization in hydroponics can offer a sustainable solution to harvest a better lettuce yield, higher phytonutrients, and environmental benefits. [ABSTRACT FROM AUTHOR]

Repeated land application of dairy manure can increase soil phosphorus above crop requirements because of manure’s low nitrogen (N) to phosphorus (P) ratio (N:P < 4:1). This soil P build-up can lead to off-site P transport and impairment of surface water quality. We evaluated a treatment process to extract P from manures, called Quick Wash, integrated with a double-stage solids separation system to recover coarse and fine manure solids. The Quick Wash process uses a combination of acid, base, and organic polymers to extract and recover P from manures, improving the N:P ratio of recovered manure solids (RMS). Results showed that coarse RMS could have use as bedding materials for dairy cows, and the fine acidified RMS with N:P > 10:1 can be used as a low-P organic soil amendment. A soil incubation test showed that acidified RMS stimulated N mineralization and nitrification having higher nitrate levels than untreated dairy slurry when incorporated into soil. Our results suggest that the inclusion of Quick Wash in a dairy manure management system can improve manure’s value, lowering costs of bedding material and manure hauling, and recover P for use as fertilizer while reducing the environmental impact of land spreading manure P.

Mineralization studies are the first step in determining the usefulness of an amendment such as fertilizer, and are essential to creating guidelines for dairy waste management to help producers make informed decisions. Our goal was to assess the effects of dairy raw, composted, and digested manure amendments on C, N, and P mineralization to evaluate the feasibility of their in-farm production and use as organic fertilizers. The liquid and solid fractions of dairy effluent (LDE, SDE), dairy effluent digestate (DED), onion–cattle manure digestate and compost (OCMD, OCMC) were characterized by chemical and spectroscopic methods. Soil microcosms with LDE, SDE, DED, OCMD and OCMC and the C, N and P mineralization were determined periodically. Elemental and structural differences among amendments led to contrasting profiles of C, N, and P mineralization, and thus to differences in nutrient availability, immobilization, and CO2 emission. All processed materials were more stable than untreated waste, reducing C emissions. Digestates showed net C immobilization, and supplied the highest levels of available N, creating a relative P deficit. Instead, the compost supplied N and P via mineralization, producing a relative P excess. Future studies should aim at evaluating fertilization strategies that combine both kinds of amendments, to exploit their complimentary agronomic characteristics. [ABSTRACT FROM AUTHOR]

Dairy products are vital components of human food, however, they are rapidly spoiled due to their high content of organic matter which encourages the growth of decomposing microbes. The recycling of dairy wastes is an ideal solution to preserve the environment, as it is in line with the principles of sustainable agriculture. In this experiment, an organic fertilizer was extracted from dairy wastes and was used for the nutrition of wheat grown on sandy soils under two-year field studies. The application rate of the extracted organic fertilizer was 8 ton ha−1. Moreover, the same rates of N, P, and K were added from inorganic fertilizers. The extracted organic fertilizer significantly (p < 0.05) enhanced the wheat growth and increased chlorophyll by 11% and 16% in the first and second season, respectively, in comparison to the inorganic fertilization. The extracted organic fertilizer significantly minimized the soil pH from an initial value of 8.00 to 7.05. The tested organic fertilizer increased the uptake of N, P, and K by 55%, 49%, and 51% above the inorganic nutrition, respectively. The wheat straw and grain yield increased by 16% and 29% as a result of the addition of the organic fertilizer extracted from dairy wastes. The dairy wastes organic fertilizer caused a notable improvement in the soil quality. The extracted organic fertilizer was able to supply wheat with its nutrient requirements as it showed a remarkable superiority over the mineral fertilization. The disposal of expired dairy waste can be managed in a way that preserves the environment by converting it to organic fertilizers. Laboratory and field experiments have proven the efficiency of the extracted organic fertilizer in nutrition of wheat plants in sandy soils with low fertility. [ABSTRACT FROM AUTHOR]

Repeated land application of dairy manure can increase soil phosphorus above crop requirements because of manure's low nitrogen (N) to phosphorus (P) ratio (N:P < 4:1). This soil P build-up can lead to off-site P transport and impairment of surface water quality. We evaluated a treatment process to extract P from manures, called Quick Wash, integrated with a double-stage solids separation system to recover coarse and fine manure solids. The Quick Wash process uses a combination of acid, base, and organic polymers to extract and recover P from manures, improving the N:P ratio of recovered manure solids (RMS). Results showed that coarse RMS could have use as bedding materials for dairy cows, and the fine acidified RMS with N:P > 10:1 can be used as a low-P organic soil amendment. A soil incubation test showed that acidified RMS stimulated N mineralization and nitrification having higher nitrate levels than untreated dairy slurry when incorporated into soil. Our results suggest that the inclusion of Quick Wash in a dairy manure management system can improve manure's value, lowering costs of bedding material and manure hauling, and recover P for use as fertilizer while reducing the environmental impact of land spreading manure P. [ABSTRACT FROM AUTHOR]

Scotta is a dairy industry waste obtained by ricotta cheese production. Because of its high availability and its high lactose content, scotta could be used as an additive to improve fermentation characteristics of alfalfa silage. Silage samples were obtained for 2 years from an alfalfa second cut, collecting the forage at three growth stages: mid bud (MB), early flowering (EF), and late flowering (LF). After wilting the forage at 38% dry matter (DM), four scotta doses were added (0, 75, 150, and 300 g/kg fresh forage) and the main chemical and microbiological characteristics were evaluated after 3, 13, and 90 days of ensiling (DOE). The lowest pH (4.3) was recorded in the EF and LF growth stages, after 90 DOE and with the highest scotta dose (300 g/kg fresh forage). After 90 DOE, the concentration of the main spoilage microorganisms and clostridial spore loads was always negligible. The addition of scotta decreased pH and fiber fractions, increased the relative feed value, and had no effect on the crude protein concentration or the total digestible nutrients. Therefore, the scotta can be successfully used as an additive to improve the fermentation characteristics of alfalfa silage. [ABSTRACT FROM AUTHOR]