Technical, economic, and environmental assessment of a collective integrated treatment system for energy recovery and nutrient removal from livestock manure

The aim of this 5-year study was to evaluate the technical, economic, and environmental performances of a collective-based integrated treatment system for bioenergy production and nutrients removal to improve the utilization efficiency and reduce the environmental impact of land applied livestock manure. The study involved 12 livestock production units located in an intensive livestock area designated as nitrate vulnerable zone with large N surplus. The treatment system consisted of an anaerobic digestion unit, a solid-liquid separation system, and a biological N removal process. Atmospheric emissions and nutrient losses in water and soil were examined for the environmental assessment, while estimated crop removal and nutrient utilization efficiencies were used for the agronomic assessment. The integrated treatment system achieved 49% removal efficiency for total solids (TS), 40% for total Kjeldahl nitrogen (TKN), and 41% for total phosphorous (TP). A surplus of 58kWh/t of treated manure was achieved considering the electricity produced by the biogas plant and consumed by the treatment plant and during transportation of raw and treated manure. A profit of 1.61 \ubf/t manure treated and an average reduction of global warming potential by 70% was also achieved. The acidification potential was reduced by almost 50%. The agronomic use of treated manure eliminated the TKN surplus and reduced the TP surplus by 94%. This collective integrated treatment system can be an environmentally and economically sustainable solution for farms to reduce N surplus in intensive livestock production areas

Effect of a biological additive on nitrogen losses from pig slurry during storage

Additives applied to animal manure slurries can affect the chemical composition and the biological processes of slurries during storage, with possible improvement of their management and reduction of environmental problems. Some new formulations are marketed claiming a nitrogen (N) removal effect due to denitrification, with the consequence of a reduced N content in the manure after storage. This study evaluated the effects of one of these commercial additives (BACTYcomplex) on slurry characteristics and N losses at a commercial piggery. The additive was applied to four different sectors of the piggery, each with an independent under-floor slurry pit; four other sectors served as controls without treatment. Pits were emptied every 4 wk, and the manure was analyzed for total and ammonia-N and total and volatile solids. Slurry samples from the last month of the on-farm assessment were removed and stored thermostatically in vessels external to the piggery. A subsample of slurry that was treated with the additive at the piggery was treated with an additional dose of additive at the beginning of long-term storage. The additive did not change the composition of the slurry during in-house storage (4 wk duration). During the 155 d of external thermostatic storage, the total solids content of treated slurry was reduced by 18% compared with control slurry, but the N content and composition of treated slurry was unaffected. The additive had a positive effect in accelerating the stabilization of the slurry but did not modify N losses

Effect of ammonia stripping and use of additives on separation of solids, phosphorus, copper and zinc from liquid fractions of animal slurries

To increase the sustainable reuse of animal manure as fertiliser, in many cases suitable treatment techniques are needed to modify the composition and obtain a balanced nutrient content. This study was conducted to evaluate the best strategies to remove solids, P, Cu and Zn, using two additives Ca(OH) 2 and Al 2 (SO 4 ) 3 , in combination with an ammonia stripping process. The assessment was carried out on five type of liquid fractions derived from the mechanical separation of: raw pig slurry, pig digested slurry, pig digested slurry after ammonia stripping, pig and cattle digested slurry, pig and cattle digested slurry after ammonia stripping. After the addition of the chemicals, the liquid fractions were mixed and then separated using a static filter. The contents of total solids P, Cu and Zn were determined. The additives effectively improved separation efficiencies which depended on the type of slurry and additive used. The P separation efficiencies ranged from 72% to 93% using Al 2 (SO 4 ) 3 , and from 20 to 74% using Ca(OH) 2 . The use of Al 2 (SO 4 ) 3 always had a more consistent effect on the removal efficiencies than Ca(OH) 2 . The ammonia stripping process, reducing the alkalinity of the digested liquid fractions, facilitated a higher concentration of elements in the separated fraction. With the addition of Al 2 (SO 4 ) 3 to digestate after stripping the concentration of P, Cu and Zn in the solid fraction generally increased when compared to the same liquid fraction without stripping. The addition of Ca(OH) 2 might be effective in removing P before the stripping process with the additional benefit to raise pH and improve the ammonia removal efficiency. These findings indicate that solid-liquid separation of animal manure slurries, assisted by chemical additives and coupled with ammonia stripping, can be a viable option for improving the sustainable use of animal manure as a fertiliser

Effects of climatic conditions on the lying behavior of a group of primiparous dairy cows

Currently, lying behavior can be assessed using continuous observations from sensors (e.g., accelerometers). The analysis of digital data deriving from accelerometers is an effective tool for studying livestock behaviors. Despite the large interest in the lying behavior of dairy cows, no reference was found in literature regarding the prediction of lying behavior as a function of the interaction of environmental parameters. The present study aimed to evaluate the influence of climatic conditions (temperature-humidity index, solar radiation, air velocity and rainfalls) on the lying behavior of a group of primiparous dairy cows, using data from accelerometers, and develop a prediction model to identify and predict the lying behavior of dairy cows as a function of the effects of environmental conditions. Results from the. GLM Procedure (SAS) showed that the model was highly significant (p < 0.001) and the r2 was 0.84. All of the effects in the model resulted in being highly significant (p < 0.001). This model, if validated properly, could be a valid early warning system to identify any deviation from the expected behavior, and to assess the effectiveness of thermal stress mitigation strategies

Nutrient losses during winter and summer storage of separated and unseparated digested cattle slurry

Management factors affect nutrient loss during animal manure slurry storage in different ways. We conducted a pilot-scale study to evaluate carbon (C) and nitrogen (N) losses from unseparated and digested dairy slurry during winter and summer storage. In addition to season, treatments included mechanical separation of digestate into liquid and solid fractions and bimonthly mixing. Chemical analyses were performed every 2 wk for the mixed materials and at the start and end of storage for unmixed materials. The parameters examined allowed us to estimate C and N losses and examine the factors that determine these losses as well as emission patterns. Gas measurements were done every 2 wk to determine the main forms in which gaseous losses occurred. To evaluate the effect of separation, measured losses and emissions of separated liquid and solid fractions were mathematically combined using the mass separation efficiency of the mechanical separator. Nutrient losses were mainly affected by climatic conditions. Losses of C (up to 23%) from unseparated, unmixed digestate and of N (38% from combined separated fractions and from unseparated digestate) were much greater in summer than in winter, when C and N losses were < 7%. Mixing tended to significantly increase N losses (P < 0.1) only in winter. Mechanical separation resulted in lower GHG emissions from combined separated fractions than from unseparated digestate. Results indicate that to maximize the fertilizer value of digested slurry, dairy farmers must carefully choose management practices, especially in summer. For separated digestates, practices should focus on storage of the liquid fraction, the major contributor of C and N losses (up to 64 and 90% of total losses, respectively) in summer. Moreover, management practices should limit NH3, the main form of N losses (up to 99.5%)

Sound analysis to predict the growth of Turkeys

Protocols for manual weighing of turkeys are not practical on turkey farms because of the large body sizes, heavy weights and flighty nature of turkeys. The sounds turkeys make may be a proxy for bird weights, but the relationship between turkey sounds and bird weights has not been studied. The aim of this study was to correlate peak frequency (PF) of vocalization with the age and weight of the bird and examine the possibility using PF to predict the weight of turkeys. The study consisted of four trials in Egypt. Sounds of birds and their weights were recorded for 11 days during the growth period in each trial. A total 2200 sounds were manually analyzed and labelled by extracting individual and general sounds on the basis of the amplitude and frequency of the sound signal. The PF of vocalizations in each trial, as well as in pooled trails, were evaluated to determine the relationship between PF and the age and weight of the turkey. PF exhibited a highly significant negative correlation with the weight and age of the turkeys showing that PF of vocalizations can be used for predicting the weight of turkeys. Further studies are necessary to refine the procedure

Fertigation of maize with digestate using drip irrigation and pivot systems

Digestate is a nutrient-rich fertilizer and appropriate techniques are required for its application during the maize season to reduce losses and increase the nitrogen use efficiency (NUE). The performance of two different fertigation techniques (drip irrigation and pivot) were assessed using the digestate liquid fraction. A two-year field test was carried out at two different sites in Lombardy, northern Italy. At each site, fertigation with pivot (P-F, site 1) or drip (D-F, site 2) systems was compared to reference fields where the same irrigation techniques without addition of digestate were used. During the two seasons, the performance of the fertigation systems, amount of fertilizers used, soil nitrogen content, yields, and nitrogen content of the harvested plants were monitored. The digestate application averaged 5 m3/ha per fertigation event with P-F and 4.9 m3/ha with D-F corresponding, respectively, to 28 and 23 kg N/ha. Both irrigation systems were suitable for fertigation provided that the digestate was adequately filtrated. Our results suggest that fertigation with digestate, if properly managed, can be applied during the growing season up to the full amount of nitrogen required by the crop

Controllo fuzzy di digestori a doppio stadio: sperimentazione a scala di laboratorio per la produzione di bioidrogeno e biometano

Il processo a doppio stadio \ue8 una semplice variante della tradizionale digestione anaerobica di biomasse che avviene in due distinti reattori in serie, che permette rese complessive migliori, oltre alla produzione di una significativa quantit\ue0 di idrogeno a fianco del classico biogas ricco in metano. A tali benefici corrispondono per\uf2 incrementi nei costi impiantistici e nella complessit\ue0 di gestione di processo che deve bilanciare le diverse esigenze dei due stadi alimentati sequenzialmente. Lo studio esplora l\u2019uso di un controllo a logica fuzzy per ottimizzare in modo dinamico il carico organico dell\u2019alimentazione, adeguandolo all\u2019andamento del processo sulla base dei valori delle principali variabili misurati online da sensori online. Nell\u2019ambito di una sperimentazione di lunga durata \ue8 stato monitorato il funzionamento di due identici impianti a doppio stadio a scala di laboratorio, confrontando il comportamento di un impianto alimentato dal sistema a controllo fuzzy con uno alimentato a carico costante. Grazie alla capacit\ue0 di adattare dinamicamente il carico organico in funzione dello stato di processo, il sistema fuzzy ha dimostrato sia capacit\ue0 di produrre significativamente pi\uf9 energia, sia di recuperare instabilit\ue0 di processo determinate da sovralimentazioni. Infine, il carattere interdisciplinare della ricerca viene poi discusso alla luce dell\u2019interessante tema del Convegno, ricavandone alcuni aspetti attuali della figura del Meccanico Agrario

Methods for measuring the behaviour of dairy cows in free stall barns

Behaviour is one of the most commonly used and sensitive indicators of animal welfare. Methods of assessing behavioural activity have changed in recent years, favouring techniques that automate monitoring and recording of animal behaviour, respect to use video recording system. The objectives of the current study were to determine the capability of electronic recording devices (HOBO Pendant G and IceTag) to measure behavioural activity of cows in comparison with video recording system. Automatic recording devices showed data of high sensitivity (Se 65 0.961) and specificity (Sp 65 0.951) for lying and standing behavioural patterns displaying predictive values close to 1.00 (PPV 65 0.966 and NPV 65 0.945). Instead, moving behavioural pattern was inadequately recorded by the IceTag device (PPV 64 0.303). Video recording systems provide a complete view of all behaviour and also of the position of the cows in the barn, but it is often time consuming and labour-intensive. Automated measurement of laterality may improve understanding the role of this aspect of lying as an indicator of cow comfort and might be useful for assessing the welfare of dairy cattle. Data loggers accurately measured all aspect of lying behaviour, while the locomotion behaviour (walking) is not well represented. The development of these data loggers may improve the information on activity of dairy cows reducing time and labour required for monitoring of behaviour

A farm-scale pilot plant for biohydrogen and biomethane production by two-stage fermentation

Hydrogen is considered one of the possible main energy carriers for the future, thanks to its unique environmental properties. Indeed, its energy content (120 MJ/kg) can be exploited virtually without emitting any exhaust in the atmosphere except for water. Renewable production of hydrogen can be obtained through common biological processes on which relies anaerobic digestion, a well-established technology in use at farm-scale for treating different biomass and residues. Despite two-stage hydrogen and methane producing fermentation is a simple variant of the traditional anaerobic digestion, it is a relatively new approach mainly studied at laboratory scale. It is based on biomass fermentation in two separate, seuqential stages, each maintaining conditions optimized to promote specific bacterial consortia: in the first acidophilic reactorhydrogen is produced production, while volatile fatty acids-rich effluent is sent to the second reactor where traditional methane rich biogas production is accomplished. A two-stage pilot-scale plant was designed, manufactured and installed at the experimental farm of the University of Milano and operated using a biomass mixture of livestock effluents mixed with sugar/starch-rich residues (rotten fruits and potatoes and expired fruit juices), afeedstock mixture based on waste biomasses directly available in the rural area where plant is installed. The hydrogenic and the methanogenic reactors, both CSTR type, had a total volume of 0.7m3 and 3.8 m3 respectively, and were operated in thermophilic conditions (55 2 °C) without any external pH control, and were fully automated. After a brief description of the requirements of the system, this contribution gives a detailed description of its components and of engineering solutions to the problems encountered during the plant realization and start-up. The paper also discusses the results obtained in a first experimental run which lead to production in the range of previous laboratory results, with a typical hydrogen and methane specific productivity of 2.2 and 0.5 Nm3/m3reactor per day, in the first and second stage of the plant respectively. At our best knowledge, this plant is one of the very first prototypes producing biohydrogen at farm scale, and it represents a distributed, small scale demonstration to obtain hydrogen from renewable waste-sources