Treated sludge from wastewater treatment plants (WWTPs) is commonly used in agriculture as fertilizers and to amend soils. The most significant health hazard for sewage sludge relates to the wide range of pathogenic microorganisms such as protozoa parasites.The objective of this study was to collect quantitative data on Cryptosporidium oocysts and Giardia cysts in the treated sludge in wastewater treatment facilities in Spain. Sludge from five WWTPs with different stabilization processes has been analysed for the presence of Cryptosporidium and Giardia in the raw sludge and after the sludge treatment. A composting plant (CP) has also been assessed. After a sedimentation step, sludge samples were processed and (oo)cysts were isolated by immunomagnetic separation (IMS) and detected by immunofluorescence assay (IFA). Results obtained in this study showed that Cryptosporidium oocysts and Giardia cysts were present in 26 of the 30 samples (86.6%) of raw sludge samples. In treated sludge samples, (oo)cysts have been observed in all WWTP’s analysed (25 samples) with different stabilization treatment (83.3%). Only in samples from the CP no (oo)cysts were detected. This study provides evidence that (oo)cysts are present in sewage sludge-end products from wastewater treatment processes with the negative consequences for public health.

Fire has been an integral part of ecosystem functioning in many biomes for a long time, but the increased intensity and frequency of wildfires often affect plant diversity and carbon storage. Prescribed burning is one of the alternatives to forest fuel management where the fire is controlled and carried out under a determined set of weather conditions and objectives. The effect of prescribed burning on plant diversity and carbon (C) storage has not been studied widely. The objective of this study was to evaluate the effect of prescribed burning on plant diversity indices, biomass stocks, and soil C storage in the tropical highland forests of Southern Mexico. We assessed plant diversity and carbon stocks at 21 sampling sites: seven with prescribed burning, seven non-burning, and seven with wildfires. We calculated tree biodiversity indices, stand structural properties, and species composition among burning treatments. We quantified C stocks in vegetation biomass by using an allometric equation and forest litter by direct sampling. We analyzed 252 soil samples for soil organic C content and other properties. The results showed that the biodiversity index was higher in sites with prescribed burning (Shannon index, H = 1.26) and non-burning (H = 1.14) than in wildfire sites (H = 0.36). There was a greater similarity in plant species composition between non-burning and prescribed burning sites compared to wildfire sites. Prescribed burning showed a positive effect on soil carbon storage (183.9 Mg C ha⁻¹) when compared to wildfire (144.3 Mg C ha⁻¹), but the difference was not statistically significant (p > 0.05) in biomass stocks. Prescribed burning in this study conserved plant diversity as well as soil carbon stocks compared to non-burning, the opposite of what we found in wildfires.

Eight different phenotypes were studied in an activated sludge process (AeR) and anaerobic digester (AnD) in a full-scale wastewater treatment plant by means of fluorescent in situ hybridization (FISH) and automated FISH quantification software. The phenotypes were ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, denitrifying bacteria, phosphate-accumulating organisms (PAO), glycogen-accumulating organisms (GAO), sulphate-reducing bacteria (SRB), methanotrophic bacteria and methanogenic archaea. Some findings were unexpected: (a) Presence of PAO, GAO and denitrifiers in the AeR possibly due to unexpected environmental conditions caused by oxygen deficiencies or its ability to survive aerobically; (b) presence of SRB in the AeR due to high sulphate content of wastewater intake and possibly also due to digested sludge being recycled back into the primary clarifier; (c) presence of methanogenic archaea in the AeR, which can be explained by the recirculation of digested sludge and its ability to survive periods of high oxygen levels; (d) presence of denitrifying bacteria in the AnD which cannot be fully explained because the nitrate level in the AnD was not measured. However, other authors reported the existence of denitrifiers in environments where nitrate or oxygen was not present suggesting that denitrifiers can survive in nitrate-free anaerobic environments by carrying out low-level fermentation; (e) the results of this paper are relevant because of the focus on the identification of nearly all the significant bacterial and archaeal groups of microorganisms with a known phenotype involved in the biological wastewater treatment.

Con el objetivo de caracterizar el suelo del agroecosistema maíz con los sistemas de producción convencional, agroecológico y mixto, para documentar e identificar estrategias que consideren los aspectos ambientales, sociales y económicos que conlleven a alternativas para la producción sostenible, se estudiaron las propiedades físico-químicas y biológicas de 35 muestras obtenidas en 28 ejidos de la región Frailesca, interpretadas con la Norma Oficial Mexicana NOM-021-RECNAT-2000. Los resultados indican una acidez generalizada para los tres sistemas con un pH de 5.05, 5.25 y 5.24, la capacidad intercambio catiónico es baja (13.96, 12.54, y 14.95 cmol(+) kg‑1) y niveles medios de materia orgánica (3.5, 2.58 y 3.45%). Así mismo, los macronutrientes, como el fósforo se encuentra en niveles altos (75.36, 74.78 y 45.05 mg kg‑1) y el potasio se encontró en niveles bajos (3.86, 3.12 y 2.66 mg kg‑1) y los micronutrientes se encuentran en niveles medios como el hierro (3.24, 2.03 y 2.62 mg kg‑1) y boro (1.58, 1.06 y 1.37 mg kg-1). Para el caso de la textura del suelo presentan suelos franco-arcillo-arenoso y franco-arenoso. Desde el punto de vista de las características biológicas del suelo, la macrofauna con el sistema agroecológico reportó mayor diversidad de seres vivos de acuerdo al índice de Shannon y Weaver (H’ = 1.121), destacan coleópteros, anélidos, himenópteros, isópteros y gasterópodos. En ese mismo sentido, para el caso de microorganismos sobresale en diversidad de microorganismos (H’ = 1.121) reportando entomopatógenos (Beauveria bassiana y Metarhizium anisopliae), fijadores de nitrógeno (Rhizobium, Azotobacter y Azospirillum) y hongos patógenos como Rizhoctonia, Fusarium y Alternaria y el sistema con menor diversidad fue el convencional con H’ = 0.789. Bajo estas condiciones el suelo, es necesario una estrategia que permita aumentar la calidad y las prácticas de agricultura puedan ser sostenibles.