The determination of fertiliser quality of the formed struvite from a WWTP.

Struvite from nutrient-rich wastewaters has been identified as a potential substitute for commercial mineral fertilisers, with the added benefit of reducing threats to global food security by prolonging phosphate rock reserves. A fertilisation test using grass (Brachiaria brizantha Marandú) and a sand column leaching test was conducted to determine the agronomic effectiveness of struvite precipitates produced from the supernatant of dewatered sewage sludge (centrate) from a municipal Wastewater Treatment Plant (WWTP). The performance of this struvite as a fertiliser was compared with biosolids and commercial fertilisers (Urea and Triple15). The results show that the concentration of heavy metals in struvite was lower than in biosolids and below the limits of Colombia and European fertiliser regulations. Struvite increased the uptake of N and P in grass, resulting in crop yields similar to other treatments tested. Struvite use as an effective slow-release fertiliser is highly dependent on the size of crystal particles, particularly in achieving low P losses, but resulted in high N loss in the sand columns tested; N loses from struvite were higher than in the commercial fertilisers due to the struvite small particle size. Therefore, struvite represents a suitable opportunity to recover and recycle nutrients from municipal sewage sludge, facilitating the effective reuse of P and N in agriculture and uptake by plants.

Effect of filter media thickness on the performance of sand drying beds used for faecal sludge management.

The effect of sand filter media thickness on the performance of faecal sludge (FS) drying beds was determined in terms of: dewatering time, contaminant load removal efficiency, solids generation rate, nutrient content and helminth eggs viability in the dried sludge. A mixture of ventilated improved pit latrine sludge and septage in the ratio 1:2 was dewatered using three pilot-scale sludge drying beds with sand media thicknesses of 150, 250 and 350 mm. Five dewatering cycles were conducted and monitored for each drying bed. Although the 150 mm filter had the shortest average dewatering time of 3.65 days followed by 250 mm and 350 mm filters with 3.83 and 4.02 days, respectively, there was no significant difference (p > 0.05) attributable to filter media thickness configurations. However, there was a significant difference for the percolate contaminant loads in the removal and recovery efficiency of suspended solids, total solids, total volatile solids, nitrogen species, total phosphorus, chemical oxygen demand, dissolved chemical oxygen demand and biochemical oxygen demand, with the highest removal efficiency for each parameter achieved by the 350 mm filter. There were also significant differences in the nutrient content (NPK) and helminth eggs viability of the solids generated by the tested filters. Filtering media configurations similar to 350 mm have the greatest potential for optimising nutrient recovery from FS.

Influence of pH on hydrothermal treatment of swine manure: Impact on extraction of nitrogen and phosphorus in process water.

This study investigates the influence of pH on extraction of nitrogen and phosphorus from swine manure following hydrothermal treatment. Conditions include thermal hydrolysis (TH) at 120°C and 170°C, and hydrothermal carbonisation (HTC) at 200°C and 250°C in either water alone or in the presence of 0.1M NaOH, H2SO4, CH3COOH or HCOOH. Phosphorus extraction is pH and temperature dependent and is enhanced under acidic conditions. The highest level of phosphorus is extracted using H2SO4 reaching 94% at 170°C. The phosphorus is largely retained in the residue for all other conditions. The extraction of nitrogen is not as significantly influenced by pH, although the maximum N extraction is achieved using H2SO4. A significant level of organic-N is extracted into the process waters following hydrothermal treatment. The results indicate that operating hydrothermal treatment in the presence of acidic additives has benefits in terms of improving the extraction of phosphorus and nitrogen.

A comparison of product yields and inorganic content in process streams following thermal hydrolysis and hydrothermal processing of microalgae, manure and digestate.

Thermal hydrolysis and hydrothermal processing show promise for converting biomass into higher energy density fuels. Both approaches facilitate the extraction of inorganics into the aqueous product. This study compares the behaviour of microalgae, digestate, swine and chicken manure by thermal hydrolysis and hydrothermal processing at increasing process severity. Thermal hydrolysis was performed at 170°C, hydrothermal carbonisation (HTC) was performed at 250°C, hydrothermal liquefaction (HTL) was performed at 350°C and supercritical water gasification (SCWG) was performed at 500°C. The level of nitrogen, phosphorus and potassium in the product streams was measured for each feedstock. Nitrogen is present in the aqueous phase as organic-N and NH3-N. The proportion of organic-N is higher at lower temperatures. Extraction of phosphorus is linked to the presence of inorganics such as Ca, Mg and Fe in the feedstock. Microalgae and chicken manure release phosphorus more easily than other feedstocks.

[Antioxidants and diabetes mellitus: review of the evidence]. / Antioxidantes y diabetes mellitus: revisión de la evidencia.

INTRODUCTION: An increase in the oxidative stress and a decrease in the antioxidant levels have been described in diabetic patients, that have been related with the etiopathogenesis of diabetes and its chronic complications. METHODS: We performed a non-systematic review to evaluate the relationship between oxidative stress and diabetes, and the possible effects of antioxidants in the prevention and treatment of diabetes and its complications. RESULTS: The intervention studies including different antioxidants have not demonstrated any beneficial effect on cardiovascular and global morbimortality in different populations, including diabetic patients. Neither of these studies has demonstrated a beneficial effect of antioxidant supplementation on the prevention of diabetes. According to these studies, these substances can decrease lipid peroxidation, LDL-cholesterol particles oxidation and improve endothelial function and endothelial-dependent vasodilatation, without significant improvement in the metabolic control of these patients. CONCLUSIONS: The current evidence does not support the use of high doses of antioxidants on the prevention and treatment of diabetes and its complications.

[Meta-analysis on the role of lycopene in type 2 diabetes mellitus]. / Meta-análisis del papel del licopeno en la diabetes mellitus tipo 2.

INTRODUCTION: lycopene is a carotene with a potent antioxidant effect found in tomato and its derivatives. Given that diabetic patients present an increased oxidative stress, lycopene could be beneficial. The aim of this scientific review has been to analyze the scientific evidence of the role of lycopene as an anti-oxidant agent in diabetes, its prevention and the metabolic control and development of complications. MATERIALS AND METHODS: We carried out a systematic review and meta-analysis. A literature search was done in Medline and the Cochrane Library, using the MeSH terms "carotenoids" OR "lycopene" AND "type 2 diabetes mellitus". The search was manually completed from the references of the papers found. The quality of the studies was assessed by using the JADAD and STROBE scales. We included a total of 10 articles. RESULTS: After adjusting for other risk factors, the OR for developing DM2 as similar among the different levels of lycopene intake. The plasma levels of lycopene increase in the intervention groups. Lycopene decreases the malonyldialdehyde and lipid peroxidation. The non-provitamin A/provitamin A carotenoids ratio is negatively associated with the risk for suffering from diabetic retinopathy. CONCLUSION: Tomato or lycopene intake increases the plasma levels of this compound. However, there is no evidence for the association between lycopene intake and the risk for having diabetes. This compound and other tomato derivatives may have a beneficial effect on the oxidative stress in diabetic patients. The non-provitamin A/provitamin A carotenoids ratio is negatively associated with the risk for suffering from diabetic retinopathy, although there are no data available on the relationship between lycopene and other diabetic complications.