Clogging in subsurface wastewater infiltration beds: genesis, influencing factors, identification methods and remediation strategies

Subsurface wastewater infiltration (SWI) is an environmentally friendly technology for the advanced treatment of domestic sewage. Clogging (including physical, chemical and biological clogging) of the porous medium not only directly reduces the hydraulic load (treatment efficiency), but also reduces the service life. Although clogging has become one of the key issues discussed in several reports, there are still several gaps in understanding, especially in its occurrence process and identification. SWI clogging causes, development process and solutions are different from those of constructed wetlands. This article quotes some reports on constructed wetlands to provide technical ideas and reference for revealing SWI clogging problems. Based on the analysis of the clogging genesis, this review gathers the main factors that affect the degree of clogging, and new methods for the identification of clogging conditions. Some preventive and unclogging measures/strategies are presented. Finally, it is suggested that to effectively alleviate the clogging phenomenon and extend the service life, priority should be given to the comprehensive analysis of wastewater quality and solid constituents accumulated in the pores. Then, the effectiveness of in-situ strategies, such as alternating operation will be the main focuses of future research.

MONITORAMENTO DA BIOINCRUSTAÇÃO EM FITAS GOTEJADORAS APLICANDO ÁGUA COM DISTINTAS TEMPERATURAS E SALINIDADES*

MONITORAMENTO DA BIOINCRUSTAÇÃO EM FITAS GOTEJADORAS APLICANDO ÁGUA COM DISTINTAS TEMPERATURAS E SALINIDADES* JORGE LUIZ DE OLIVEIRA CUNHA1; SUEDÊMIO DE LIMA SILVA2; RAFAEL OLIVEIRA BATISTA2; BLAKE CHARLES DINIZ MARQUES2; DANIELA DA COSTA LEITE COELHO2 E KETSON BRUNO SILVA1 1 Doutores em Manejo de Solo e Água, Departamento de Ciências Agronômicas e Florestais, Universidade Federal Rural do Semi-Árido - campus Mossoró- RN, Avenida Francisco Mota, n° 572, Bairro Costa e Silva, Mossoró - RN, CEP: 59.625-900, Brasil, [email protected]; [email protected]. 2 Professores do Departamento de Engenharia e Ciências Ambientais, Universidade Federal Rural do Semi-Árido - campus Mossoró- RN, Avenida Francisco Mota, n° 572, Bairro Costa e Silva, Mossoró - RN, CEP: 59.625-900, Brasil, [email protected]; [email protected]; [email protected]; [email protected]. *O artigo foi gerado a partir da tese do primeiro autor. 1 RESUMO No campo, as fitas gotejadoras são expostas a agentes físico-químicos e microbiológicos da água de irrigação que potencializam a redução do ciclo operacional pelo processo de bioincrustação nos emissores. Objetivou-se com este trabalho analisar o nível de contribuição da temperatura e salinidade da água subterrânea, na evolução da bioincrustação em emissores de fitas gotejadoras, utilizando-se o coeficiente de uniformidade de distribuição (CUD), vazão dos emissores (Q) e imagens da Microscopia Eletrônica de Varredura (MEV). Para isso, montou-se uma bancada experimental visando o ensaio de três tipos de fitas gotejadoras (MI, MII e MIII) que operaram em quatro ciclos de operação (100, 250, 500 e 750h). As fitas gotejadoras aplicaram água com temperaturas de 20 e 30°C e salinidades que variaram de 0,52 a 2,56 dS m-1. Após o término de cada ciclo de operação, os valores de CUD e Q foram calculados, e coletaram-se amostras das fitas gotejadoras para monitoramento da bioincrustação utilizando-se o MEV. O aumento nos valores de temperatura e salinidade da água não acarretou elevação dos níveis de entupimento. Porém, a fita gotejadora MI, de menor comprimento do emissor e vazão nominal, foi a mais suscetível à bioincrustação, resultante da combinação de mucilagens bacterianas e precipitados químicos. Palavras-chave: qualidade da água, entupimento químico e biológico, vida útil. CUNHA, J. L. O.; SILVA, S. L.; BATISTA, R. O.; MARQUES, B. C. D.; COELHO, D. C. L.; SILVA, K. B. MONITORING BIOFOULING IN DRIP TAPES BY APPLYING WATER WITH DIFFERENT TEMPERATURES AND SALINITIES 2 ABSTRACT In the field, drip tapes are exposed to physical-chemical and microbiological agents in irrigation water that enhance the reduction of the operational cycle by the biofouling process at the emitters. The objective of this work was to analyze the level of contribution of groundwater temperature and salinity in the evolution of biofouling of drip tape emitters, using the distribution uniformity coefficient (DU), emitters flow rate (FR) and Scanning Electron Microscopy (SEM) images. To this end, an experimental bench was set up to test three types of drip tapes (MI, MII and MIII) that operated in four operating cycles (100, 250, 500 and 750h). The drip tapes applied water with temperatures of 20 and 30°C and salinities ranging from 0.52 to 2.56 dS m-1. After the end of each operation cycle, DU and FR values were determined, and samples of the drip tapes were collected to monitor bio-encrustation using SEM. The increase in temperature and salinity values of the water did not increase the levels of clogging. However, drip tape MI, with the shortest emitter length and nominal flow, was the most susceptible to biofouling, resulting from the combination of bacterial mucilage and chemical precipitates. Keywords: water quality, chemical and biological clogging, service life.

WATER DAMS FOR USE IN DRIP IRRIGATION IN THE CITY OF PENEDO / AL: PHYSICO-CHEMICAL AND BIOLOGICAL QUALITY

In areas where rainfall is irregular or not reaches the required the supply for cane cultivation, irrigation is essential. The introduction of drip irrigation (with surface or underground micro-sprinklers), has been one of the factors that contributed to the increase in sugar and alcohol productivity in the region of Alagoas. This study outlined a profile of physico-chemical and biological features of impounded water dam “Salvador Lyra”, in the city of Penedo-AL, used to irrigate crops in a sugarcane mill, with the purpose to know the causes of obstructions detected in the issuing of the drip irrigation system, and to propose consistent control measures. During the period of one year, samples from three points along the dam were subjected to microbiological analysis and pH, hardness, electrical conductivity, concentraction of total dissolved solids, dissolved oxygen and Fe2. With respect to microbiological analysis, it was isolated from the neutral waters an aerobic bacteria producing siderophore iron chelators, classified as the species Pseudomonas aeruginosa (Schroeter 1872) Migula (1900), and the results of physico-chemical analysis showed the prevalence of with a high risk of biological clogging (> 50,000 cells / mL).