The Treatment of Shenzhen Coastal Polluted Water by Composites of Bio- Flocculants -Bacteria-Algae

Abstract

IntroductionCoastal water pollution can cause eutrophication, frequent red tides and marine biodiversity damage. Thus, the heavy pollution of coastal waters is a serious problem all over the world [1][2][3][4], such as in the western coastal waters of Shenzhen Bay [5][6][7]. Coastal pollution has a negative effect on the ocean ecology and on the surrounding residents [8][9][10][11]. Some methods can be used to restore the pollution. A sustainable plant-based restoration method has been introduced from Europe [12]. Additionally, coastal mud flat wetlands have specific optimization functions [13][14][15][16]. Singapore has used bio-floating beds and other methods to treat the pollution in the neritic zone for the past 100 years, and the results have proven successful. The restorative plants can reduce the concentrations of nitrogen, phosphorus and other nutritive salts [17][18][19], and this technology was applied in a bio-floating bed [18,[20][21][22]. The water quality and ecological characteristics in the demonstration area had improved [23,24].Flocculation-based precipitation technology has been widely used as the main technology to treat sewage [25][26][27][28][29][30]. It is a relatively cheap, efficient and quick method. In particular, biological polysaccharidebased materials used as adsorbents to treat polluted water represent an environmentally friendly method [31][32][33]. However, this method is seldom used in the treatment of polluted coastal waters.Recently, microbial communities have been used to reduce the discharge of coastal sewage [34][35][36][37][38][39][40]. There are some reports on microbial compounds used in marine aquaculture wastewater restoration [41], but few on microbial compounds used in polluted marine water restoration. However, these microbial compounds have many unstable factors because of the mobility and openness of the neritic zone and tidal changes. Therefore, further efforts are needed to solve the problem of offshore pollution. Coastal water purification and silt clearance are greatly needed to restore the coastal ecology. Materials and Methods Study domain and sample collectionThe study domain is located on the northwestern offshore of ShenZhen Bay. The coastal sewage collection occurred over a period of four months between October 2012 and January 2013. Dissolved oxygen (DO) was detected at the seashore immediately when the samples were collected. All samples were transported to the laboratory and analyzed within 2 hours. Water samples (black, smelly polluted water) were collected from ShenZhen Bay, located at E114 degrees (113.56', 54.63") and N23 degrees (22.33' 43.79") (H: 4.4 m, precision: 5.9 m). Treatment methods of the polluted water and detection parameters of the water qualityThe water quality was then detected after 10 days. The water quality analysis measured 8 parameters, including dissolve oxygen (DO), turbidity, suspended solids (SS), chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN), total phosphate (TP), and harmful marine vibrio...