The ammonia concentrations in 1.25 and 2.3 metre deep waste stabilization ponds at Extrabes N.B. Brazil receiving domestic sewage were largely independent of the surface organic loadings on the deep ponds at least above loading rates of 200 kg BOD5 ha−1 d−1, but varied with time between 14 and 29 mg L−1 (NH3-N). During daylight, pH values reached about 9.0 (or sometimes higher) in the surface water layers as a result of algal photosynthesis. Laboratory growth studies showed that a pond isolate of Chlorella was more tolerant to ammonia than the Euglena species and grew in media containing l0mM ammonia at a pH of 9.0 and a temperature of 25°C when 40% of the total ammonia concentration was in the toxic unionised NH3 form. This tolerance would appear to be inherent since the Chlorella was isolated from ponds containing ammonia concentrations at 1 to 2mM and was subsequently maintained routinely in the laboratory at such ammonia levels. The differential sensitivity to ammonia exhibited by pond algae is discussed in terms of waste stabilization pond performance.

RESUMOEsta pesquisa, realizada com o milho forrageiro híbrido AG 1051, na Estação de Tratamento de Esgotos de Campina Grande, PB, teve como objetivo analisar os efeitos residuais da água residuária e da adubação nitrogenada, aplicadas em cultivo de algodão herbáceo anteriormente realizado na área de estudo, sobre a produção do milho com palha, sem palha e em grãos. O delineamento experimental foi em blocos casualizados em esquema fatorial [(2 x 5) + 2], com os fatores: dois tipos de água de irrigação (água de abastecimento e água residuária), cinco doses de nitrogênio (0, 60, 90, 120 e 180 kg N ha -1 e adubação de fundação com P e K) e duas testemunhas (água de abastecimento e água residuária), com quatro repetições. Os resultados mostraram aumento linear na produção de milho, em função do aumento das doses de nitrogênio, tendo-se verificado incremento de 21,37% entre as doses de 0 a 60 kg de N ha -1 e queda de 12,47% quando se aumentou a dose de 60 para 90 kg de N ha -1 , aumento de 7,07 e de 19,9% entre a aplicação da dose de 90 para 120 kg de N ha -1 e de 120 para 180 kg de N ha -1 , respectivamente e, ainda, que a irrigação com água residuária promoveu incremento na produção de 144%, em relação à produção, alcançada com água de abastecimento. Palavras-chave: reúso, nitrogênio, produtividadeEffect of irrigation with treated wastewater on production of forage corn ABSTRACTThe research accomplished with the hybrid forage corn AG 1051, was conducted in the Sewar Treament station of Campina Grande city, Paraíba state, Brazil. The objective was to analyze the residual effects of wastewater and of nitrogen manuring on production of corn with straw, without straw and in grains. The experimental design was in randomized blocks with factorial scheme (2 x 5 + 2), where the factors were: two types of irrigation water (water of municipal supply and treated wastewater), five doses of nitrogen (0, 60, 90, 120 and 180 kg N ha -1 and basal manuring with P and K) and two controls (water of municipal supply and treated wastewater), with four replications. The results showed that there was linear increase in corn production as a function of the increase of nitrogen doses incorporated to the soil, having verified an increment of 21.37% between doses of 0 and 60 kg N, reduction of 12.47% when the dose increased from 60 to 90 kg of N, increase of the production of 7.07 and 19.9% among the application of the dose from 90 to 120 kg N and from 120 to 180 kg N, respectively; and further the irrigation with wastewater promoted an increment in the production of 144%, compared to the production obtained with municipal supply water.

A cultura do capim-elefante pode dar uma grande contribuição na pecuária, pois é um excelente alimento para o gado, e como biomassa para fins energéticos. Uma das gramíneas forrageiras de mais alto potencial produtivo. O experimento foi conduzido de fevereiro a novembro de 2012, em escala real, numa área de 1 ha, no entorno da ETE do município de Pendências/RN, com o objetivo de avaliar o desenvolvimento e a produtividade de Capim-elefante-Roxo, para alimentação animal e matéria prima para produção de biomassa com fins energéticos. O delineamento experimental foi inteiramente casualizado, com dois tratamentos: um irrigado diariamente (duas fazes) e outro irrigado três vezes por semana (uma fase). A cada 20 dias foram analisadas 10 plantas em cada fase. As variáveis avaliadas foram: altura da planta, diâmetro caulinar, tamanho e largura da folha. Aos 160 dia após o plantio foi feito o corte e determinada a massa verde e massa seca do capim. Os resultados obtidos foram bastante animadores, pois a produtividade nas duas fases do primeiro tratamento foi de 136 ton/ha e 121,6 ton/ha de massa verde; no tratamento (2), o rendimento foi similar, 136 ton/ha. A quantidade de matéria seca foi de 43,5 e 39 ton/ha no tratamento 1, e 37 ton/ha no tratamento 2. O resultado indica que o cultivo de capim-elefante-Roxo deve ser aprimorado no meio rural produtivo do semiárido potiguar, e, por conseguinte, na região nordeste do Brasil.

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This study compared the behaviour of pathogenic bacteria (Salmonella and Listeria), faecal indicators (faecal coliforms FC and faecal streptococci FS), somatic coliphages and F-specific bacteriophages in an urban river contaminated with domestic sewage and surface run-off from agricultural and cattle grazing lands. The influence of physical and chemical parameters was also investigated as well as Salmonella and Listeria serotype diversity and drug resistance patterns. Faecal contamination was high (FC = 5 x 10(6) - 4 x 10(3) CFU/100 mL; FS = 4 x 10(5) - 2 x 10(2) CFU/100 mL) but decreased along the river by up to 99.5% following 47% reduction of BOD5 and 91% increase of DO, both associated with the self purification process. Somatic coliphages (6.9 x 10(5) - 1 x 10(3) PFU/100 mL) and F-specific bacteriophages (5.8 x 10(4) - 65 PFU/100 mL) behaved similarly with reductions of 99.85%. Salmonella and Listeria were isolated at all sampling points with highestfrequencies (91-100%) at those with sewage discharge and rural water run-off. The lowest value (35%) occurred at the end of the river where it was (a) wider and shallower, (b) it ran slower and was warmer (29-33 degrees C), (c) the pH was alkaline (8.2-9.9), (d) electrical conductivity (2,200-5,800 microS/cm) and DO (6-13 mg/L) were highest. Pathogen decline did not follow exactly FC and FS reduction patterns, while physical and chemical parameters apparently did not interfere with Salmonella and Listeria survival to the same extent as they did with FC and FS. Somatic coliphages and F-specific bacteriophages did not show more resistance than bacterial indicators. Catchment area contribution seemed to be more significant for pathogens than for indicators and rainy periods increased pathogenic isolation frequency. Five Salmonella serotypes and five serogroups were identified. S. hadar and serogroup E were predominant (50%); both are increasing in Brazil apparently from animal sources. Nearly 25% of Salmonella strains were resistant to at least one of twelve antimicrobials tested. Resistance to tetracycline was common (17%) followed by cefalotine (3%). Five Listeria serogroups were isolated and L. grayi (43%) and L. monocytogenes (9%) were present at all points. Listeria drug resistance rates were 100% for oxaciline followed by clindamicine (97%), tetracycline (34%) and vancomycin (32%). Both pathogenic bacterial strains presented resistance to the same drugs observed in humans and warm blood animals but the high number of sensitive strains and the low numbers of strains resistant to more than one drug was not expected because of the heavy anthropogenic impact in this basin.